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  • 1.
    Anwar Zainuddin, Ahmad
    et al.
    IIUM, Malaysia.
    Nurashikin Nordin, Anis
    IIUM, Malaysia.
    Ab Rahim, Rosminazuin
    IIUM, Malaysia.
    Mak, Wing Cheung
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Modeling of a Novel Biosensor with Integrated Mass and Electrochemical Sensing Capabilities2016In: 2016 IEEE EMBS CONFERENCE ON BIOMEDICAL ENGINEERING AND SCIENCES (IECBES), IEEE , 2016, p. 420-425Conference paper (Refereed)
    Abstract [en]

    Rapid development in technology and society has generated diverse developments in many fields including biosensors in healthcare application. Here, the design of integrated biosensor comprises mass sensing (Quartz Crystal Microbalance) and electrochemistry sensing (Electrochemical Impedance Spectroscopy, EIS and Cyclic Voltammetry, CV) will be presented. The integrated sensor system is developed based on the innovative use of the top electrode of a quartz crystal microbalance (QCM) resonator as a working electrode for the electrochemistry technique. Integration of QCM with the electrochemistry technique is realized by fabricating a semicircular counter electrode near the upper electrode on the same side of the quartz crystal. CV and EIS measurement was conducted using finite element modeling, COMSOL (TM) 5.2 with the probe marker of 1 mmol L-1 of [Fe(CN)(6)](3-/4-). CV test was done to study the effect between increasing scan rate and peak current (anodic and cathodic) in observing the reversible electrochemical process. This observation is crucial in ensuring the electrochemical processes follow the Randles-Sevcik equation in characterizing the platform changes behavior. Later, EIS test was performed in order to measure the radius of the semicircle which reflects the charge transfer resistance (R-CT) of the redox marker. To show the effectiveness of this sensor, gold immobilization surface was electrochemically simulated and reported. Thus, an ultra-sensitive biosensor that capable to produce multi-analysis in the detection of biological targets in terms of electrochemical change of electrode interfaces, which is the crucial step towards the engineering of advanced bioelectronics.

  • 2.
    Azzouzi, Sawsen
    et al.
    Not Found:Linkoping Univ, Biosensors and Bioelect Ctr, Dept Phys Chem and Biol IFM, S-58183 Linkoping, Sweden; Univ Sousse, Tunisia; Ctr Res Microelect and Nanotechnol Sousse, Tunisia.
    Fredj, Zina
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering. Univ Sousse, Tunisia; Ctr Res Microelect and Nanotechnol Sousse, Tunisia.
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering. Cranfield Univ, England.
    Ben Ali, Mounir
    Univ Sousse, Tunisia; Ctr Res Microelect and Nanotechnol Sousse, Tunisia.
    Mak, Wing Cheung
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Generic Neutravidin Biosensor for Simultaneous Multiplex Detection of MicroRNAs via Electrochemically Encoded Responsive Nanolabels2019In: ACS SENSORS, ISSN 2379-3694, Vol. 4, no 2, p. 326-334Article in journal (Refereed)
    Abstract [en]

    Current electrochemical biosensors for multiple miRNAs require tedious immobilization of various nucleic acid probes. Here, we demonstrate an innovative approach using a generic neutravidin biosensor combined with electrochemically encoded responsive nanolabels for facile and simultaneous multiplexed detection of miRNA-21 and miRNA-141. The selectivity of the biosensor arises from the intrinsic properties of the electrochemically encoded responsive nanolabels, comprising biotinylated molecular beacons (biotin-MB) and metal nanoparticles (metal-NPs). The procedure is a simple one-pot assay, where the targeted miRNA causes the opening of biotin-MB followed by capturing of the biotin-MB-metal-NPs by the neutravidin biosensor and simultaneous detection of the captured metal-NPs by stripping square-wave voltammetry (SSWV). The multiplexed detection of miRNA-21 and miRNA-141 is achieved by differentiation of the electrochemical signature (i.e., the peak current) for the different metal-NP labels. The biosensor delivers simultaneous detection of miRNAs with a linear range of 0.5-1000 pM for miRNA-21 and a limit of detection of 0.3 pM (3 sigma/sensitivity, n = 3), and a range of 50-1000 pM for miRNA-141, with a limit of detection of 10 pM. Furthermore, we demonstrate multiplexed detection of miRNA-21 and miRNA-141 in a spiked serum sample.

  • 3.
    Azzouzi, Sawsen
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering. University of sousse, Tunisia.
    Kor, Kalamodin
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering. Damghan University, Iran.
    Ben Ali, Mounir
    University of sousse, Tunisia.
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Mak, Wing Cheung
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Beni, Valerio
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    A single probe based impedimetric biosensor for the label free, real time monitoring of microRNA-21 biomarker2016In: Biosensors 2016 – The World Congress on Biosensors, Gothenburg, Sweden, 25-27 May 2016, Elsevier, 2016Conference paper (Other academic)
  • 4.
    Azzouzi, Sawsen
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering. University of Sousse, Tunisia.
    Mak, Wing Cheung
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Kor, Kamalodin
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering. Iranian National Institute Oceanog and Atmospher Science, Iran.
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Ben Ali, Mounir
    University of Sousse, Higher Institute of Applied Sciences and Technology of Sousse, GREENS-ISSAT, Cité Ettafala, 4003 Ibn Khaldoun Sousse, Tunisia.
    Beni, Valerio
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering. ACREO SWEDISH ICE AB, Sweden.
    An integrated dual functional recognition/amplification bio-label for the one-step impedimetric detection of Micro-RNA-212017In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 92, p. 154-161Article in journal (Refereed)
    Abstract [en]

    Alteration in expression of miRNAs has been correlated with different cancer types, tumour stage and response to treatments. In this context, a structurally responsive oligonucleotide-based electrochemical impedimetric biosensor has been developed for the simple and sensitive detection of miRNA-21. A highly specific biotinylated DNA/LNA molecular beacon (MB) probe was conjugated with gold nanoparticles (AuNPs) to create an integrated, dual function bio-label (biotin-MB-AuNPs) for both biorecognition and signal generation. In the presence of target miRNA-21, hybridisation takes place resulting in the "activation" of the biotin-MB; this event makes the biotin group, which was previously "protected" by the steric hindrance of the MB stem-loop structure, accessible. The activated biotin-MB-AuNPs/miRNA complexes become available for capture, via supramolecular interaction, onto a nentravidin-modified electrode for electrochemical transduction. The binding event results in a decrease of the charge transfer resistance at the working electrode/electrolyte interface. The biosensor responded linearly in the range 1-1000 pM of miRNA-21, with a limit of detection of 0.3 pM, good reproducibility (Relative Standard deviation (RSD) =3.3%) and high selectivity over other miRNAs (i.e. miRNA221 and miRNA-205) sequences. Detection of miRNA-21 in spiked serum samples at clinically relevant levels (low pM range) was also demonstrated, thus illustrating the potential of the biosensor for point-of-care clinical applications. The proposed biosensor design, based on the combination of a neutravidin transducing surface and the dual-function biotin-MB-AuNPs bio-label, provides a simple and robust approach for detection of short-length nucleic acid targets, such as miRNAs.

  • 5.
    Bai, Jianhao
    et al.
    National University of Singapore.
    Beyer, Sebastian
    National University of Singapore.
    Mak, Wing Cheung
    Hong Kong University of Science and Technology, Hong Kong, China .
    Trau, Dieter
    National University of Singapore.
    Fabrication of inflated LbL microcapsules with a ‘bead-in-a-capsule’ morphology2009In: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, Vol. 5, p. 4152-4160Article in journal (Refereed)
    Abstract [en]

    The fabrication of inflated Layer-by-Layer (LbL) microcapsules with a unique ‘bead-in-a-capsule’ morphology is presented. Currently, the fabrication of LbL microcapsules using conventional aqueous LbL techniques usually results in microcapsules with a two-phase system (LbL capsular wall with an air, liquid, solid or hydrogel core). Here, we present the fabrication of inflated LbL microcapsules with a unique three-phase system (LbL capsular wall, hydrogel microbead in an aqueous core) by using the Reverse-Phase LbL (RP-LbL) technique. The RP-LbL technique is performed in an organic solvent and allows encapsulation of water-soluble templates and molecules with high efficiency. Firstly, the RP-LbL technique is used to coat polymer layers onto agarose microbeads containing TRIS buffer for the formation of LbL capsular walls onto the microbeads and to minimize out-diffusion of encapsulated TRIS. Next, the polymer-coated agarose microbeads are transferred from an organic to an aqueous solvent where the TRIS molecules induce an osmotic pressure in the microcapsules' interior. This pressure drives the inflation of the LbL microcapsules that causes the expansion of the LbL capsular walls. Fluorescence staining reveals that the inflated LbL microcapsules consist of an agarose microbead suspended within the aqueous interior of the capsule but still attached to the LbL capsular wall at one point; thereby displaying a ‘bead-in-a-capsule’ morphology. It was demonstrated that the degree of inflation depends on the concentration of pre-loaded TRIS and the number of coated polymer layers. Also, ADOGEN® 464 (a cationic surfactant) is required for the fabrication of the inflated LbL microcapsules. The mass of dextran macromolecules (65–2000 kDa) diffusing through the LbL capsular wall had decreased by at least 49% after expansion of the capsular wall. Inflated microcapsules were shown to be capable of controlling the distribution of two different materials internally. Hence, it is possible that inflated microcapsules can permit localized control over chemical or enzymatic reactions for future uses in biomedical applications.

  • 6.
    Beyer, Sebastian
    et al.
    Gelsenkirchen University of Applied Sciences, Germany.
    Mak, Wing Cheung
    National University of Singapore.
    Trau, Dieter
    National University of Singapore.
    Reverse-phase LbL-encapsulation of highly water soluble materials by layer-by-layer polyelectrolyte self-assembly2007In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 23, no 17, p. 8827-8832Article in journal (Refereed)
    Abstract [en]

    We report on a novel method for the encapsulation of highly water soluble materials by using layer-by-layer (LbL) polyelectrolyte self-assembly. State of the art polyelectrolyte self-assembly LbL coating and encapsulation methods are only applicable to insoluble or poorly water soluble template materials, because the process is performed in water causing dissolution of the solid template. Our method extends the material spectrum to highly water soluble template materials by using non-ionized polyelectrolytes in an organic phase (reverse-phase) instead of polyelectrolyte salts in an aqueous environment. By using the reverse-phase layer-by-layer (RP-LbL) technique, we have demonstrated the direct encapsulation of proteins, glucose, vitamin C, and inorganic salts in the solid state. Multilayer deposition was proven, layer thickness was determined by AFM, and the advantage of the method to prepare powders of encapsulated materials was demonstrated. The method is simple, robust, and applicable to a broad range of substances with potential applications in several industries.

  • 7.
    Chan, Cangel Pui Yee
    et al.
    Chinese University of Hong Kong, Hong Kong, China .
    Mak, Wing Cheung
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Cheung, Kwan Yee
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Health Sciences.
    Sin, King Keung
    Hong Kong University of Science and Technology, Hong Kong, China.
    Yu, Cheuk Man
    Chinese University of Hong Kong, Hong Kong, China.
    Rainer, Timothy H.
    Chinese University of Hong Kong, Hong Kong, China.
    Renneberg, Reinhard
    Hong Kong University of Science and Technology, Hong Kong, China.
    Evidence-Based Point-of-Care Diagnostics: Current Status and Emerging Technologies2013In: Annual Review of Analytical Chemistry, ISSN 1936-1327, Vol. 6, p. 191-211Article in journal (Refereed)
    Abstract [en]

    Point-of-care (POC) diagnostics brings tests nearer to the site of patient care. The turnaround time is short, and minimal manual interference enables quick clinical management decisions. Growth in POC diagnostics is being continuously fueled by the global burden of cardiovascular and infectious diseases. Early diagnosis and rapid initiation of treatment are crucial in the management of such patients. This review provides the rationale for the use of POC tests in acute coronary syndrome, heart failure, human immunodeficiency virus, and tuberculosis. We also consider emerging technologies that are based on advanced nanomaterials and microfluidics, improved assay sensitivity, miniaturization in device design, reduced costs, and high-throughput multiplex detection, all of which may shape the future development of POC diagnostics.

  • 8.
    Cheung, Kitt
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Medicine and Health Sciences.
    Lai, Kwok Kei
    Hong Kong Univ Sci and Technol, Peoples R China.
    Mak, Wing Cheung
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Fabrication of Protein Microparticles and Microcapsules with Biomolecular Tools2018In: Zeitschrift fur physikalische Chemie (Munchen. 1991), ISSN 0942-9352, Vol. 232, no 5-6, p. 759-771Article in journal (Refereed)
    Abstract [en]

    Microparticles have attracted much attention for medical, analytical and biological applications. Calcium carbonate (CaCO3) templating method with the advantages of having narrow size distribution, controlled morphology and good biocompatibility that has been widely used for the synthesis of various protein-based microparticles. Despite CaCO3 template is biocompatible, most of the conventional methods to create stable protein microparticles are mainly driven by chemical crosslink reagents which may induce potential harmful effect and remains undesirable especially for biomedical or clinical applications. In this article, we demonstrate the fabrication of protein microparticles and microcapsules with an innovative method using biomolecular tools such as enzymes and affinity molecules to trigger the assembling of protein molecules within a porous CaCO3 template followed by a template removal step. We demonstrated the enzyme-assisted fabrication of collagen microparticles triggered by transglutaminase, as well as the affinity-assisted fabrication of BSA-biotin avidin microcapsules triggered by biotin-avidin affinity interaction, respectively. Based on the different protein assemble mechanisms, the collagen microparticles appeared as a solid-structured particles, while the BSA-biotin avidin microcapsules appeared as hollow-structured morphology. The fabrication procedures are simple and robust that allows producing protein microparticles or microcapsules under mild conditions at physiological pH and temperature. In addition, the microparticle morphologies, protein compositions and the assemble mechanisms were studied. Our technology provides a facile approach to design and fabricate protein microparticles and microcapsules that are useful in the area of biomaterials, pharmaceuticals and analytical chemistry.

  • 9.
    Cheung, Kwan Yee
    et al.
    National University of Singapore.
    Mak, Wing Cheung
    National University of Singapore.
    Trau, Dieter
    National University of Singapore.
    Reusable optical bioassay platform with permeability-controlled hydrogel pads for selective saccharide detection2008In: Analytica Chimica Acta, ISSN 0003-2670, E-ISSN 1873-4324, Vol. 607, no 2, p. 204-210Article in journal (Refereed)
    Abstract [en]

    A reusable optical bioassay platform using permeability-controlled hydrogel pads for selective saccharide detection has been developed. An optical glucose detection assay based on fluorescence resonance energy transfer (FRET) between dye-labeled dextran and Concanavalin A (ConA) was incorporated into hydrogel pads by entrapment. The hydrogel pads are constructed from hemispherical hydrogel attached onto hydrophobic surfaces of a microtiter plate. The resulted hemispherical hydrogel pads entrapping the sensing biological materials were further surface coated with polyelectrolyte multilayers through a Layer-by-Layer (LbL) self-assembly process to create a permeability-controlled membrane with nanometer thickness. The selective permeable LbL film deposited on the hydrogel surface allows small molecular weight analytes to diffuse into the hydrogel pads while the large molecular weight sensing biological molecules are immobilized. An encapsulation efficiency of 75% for the ConA/Dextran complex within the coated hydrogel pads was achieved and no significant leakage of the complex was observed. Glucose calibration curve with linear range from 0 to 10 mM glucose was obtained. Selective permeability of the hydrogel pads has been demonstrated by measurement of saccharides with various molecular weights. The LbL hydrogel pads could selectively detect monosaccharides (glucose, MW = 180) and disaccharides (sucrose, MW = 342) while polysaccharides (dextran, MW ∼ 70 kDa) cannot diffuse through the LbL layer and are excluded. LbL hydrogel pads allow regeneration of the FRET system with good signal reproducibility of more than 90% to construct a reusable and reagentless optical bioassay platform.

  • 10.
    Cheung Mak, Wing
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Kwan Yee, Cheung
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Medicine and Health Sciences.
    Orban, Jenny
    Linköping University, Faculty of Science & Engineering. Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics.
    Lee, Chyan-Jang
    Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics. Linköping University, The Institute of Technology.
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Griffith, May
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Medicine and Health Sciences.
    Surface-Engineered Contact Lens as an Advanced Theranostic Platform for Modulation and Detection of Viral Infection2015In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 7, no 45, p. 25487-25494Article in journal (Refereed)
    Abstract [en]

    We have demonstrated an entirely new concept of a wearable theranostic device in the form of a contact lens (theranostic lens) with a dual-functional hybrid surface to modulate and detect a pathogenic attack, using a the corneal HSV serotype-1 (HSV-1) model. The theranostic lenses were constructed using a facile layer-by-layer surface engineering technique, keeping the theranostic lenses with good surface wettability, optically transparency, and nontoxic toward human corneal epithelial cells. The theranostic lenses were used to capture and concentrate inflammatory cytokines such as interleukin-1 alpha (IL-1 alpha), which is upregulated during HSV-1 reactivation, for sensitive, noninvasive diagnostics. The theranostic lens also incorporated an antiviral coating to serve as a first line of defense to protect patients against disease. Our strategy tackles major problems in tear diagnostics that are mainly associated with the sampling of a relatively small volume of fluid and the low concentration of biomarkers. The theranostic lenses show effective anti-HSV-1 activity and good analytical performance for the detection of IL-1a, with a limit of detection of 1.43 pg mL(-1) and a wide linear range covering the clinically relevant region. This work offers a new paradigm for wearable noninvasive healthcare devices combining diagnosis and protection against disease, while supporting patient compliance. We believe that this approach holds immense promise as a next-generation point-of-care and decentralized diagnostic/theranostic platform for a range of biomarkers.

  • 11.
    Fathollahzadeh, Marjam
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering. College of Chemistry, Institute for Advanced Studies in Basic Sciences, Gava Zang, Zanjan, Iran.
    Tyagi, Manav
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Maziz, Ali
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Filippini, Daniel
    Linköping University, Department of Physics, Chemistry and Biology, Chemical and Optical Sensor Systems. Linköping University, Faculty of Science & Engineering.
    Haghighi,, B
    Department of Chemistry, College of Sciences, Shiraz University, Shiraz, Iran.
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Mak, Wing Cheung
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Dynamic gates based on polypyrrole for microfluidic bioanalytical applications2016In: Biosensors 2016 – The World Congress on Biosensors, Gothenburg, Sweden, 25-27 May 2016, Elsevier, 2016Conference paper (Other academic)
  • 12.
    Fredj, Zina
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering. University of Sousse, Higher Institute of Applied Sciences and Technology of Sousse, GREENS-ISSAT, Cité Ettafala, 4003 Ibn Khaldoun Sousse, Tunisia.
    Azzouzi, Sawsen
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering. University of Sousse, Higher Institute of Applied Sciences and Technology of Sousse, GREENS-ISSAT, Cité Ettafala, 4003 Ibn Khaldoun Sousse, Tunisia.
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Ali, Mounir, Ben
    University of Sousse, Higher Institute of Applied Sciences and Technology of Sousse, GREENS-ISSAT, Cité Ettafala, 4003 Ibn Khaldoun Sousse, Tunisia.
    Mak, Wing Cheung
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Neutravidin biosensor for direct capture of dual-functional biotin-molecular beacon-AuNP probe for sensitive voltammetric detection of microRNA2017In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 248, p. 8p. 77-84Article in journal (Refereed)
    Abstract [en]

    We have demonstrated a new approach using a neutravidin-based biosensor combined with a dual-function gold nanoparticle (AuNP) biolabel, for simple and sensitive detection of microRNA-21 (miRNA-21). The selectivity of the biosensor is provided by the intrinsic properties of the dual-functional biotin-MB-AuNP label. The assay procedure is relatively simple, exploiting a one-pot assay concept where the affinity capture of the miRNA-21/dual-functional biotin-MB-AuNP complex, via the strong biotin-neutravidin supramolecular interaction, and simultaneous detection of the captured AuNPs label with stripping voltammetry, is performed in a single step. This electrochemical miRNA biosensor could detect miRNA-21 with limit of detection of 0.1×10less thansuperscriptgreater than−12less than/superscriptgreater than and a dynamic range from 0.5×10less thansuperscriptgreater than−12less than/superscriptgreater than to 1.0×10less thansuperscriptgreater than−9less than/superscriptgreater thanM. The performance of the miRNA-21biosensor was further improved after silver deposition onto the AuNPs, delivering an enhanced detection limit of 4.0×10less thansuperscriptgreater than−15less than/superscriptgreater thanM of miRNA-21, and an extremely wide analytic dynamic range from 10×10less thansuperscriptgreater than−15less than/superscriptgreater than to 1×10less thansuperscriptgreater than−9less than/superscriptgreater thanM (5 orders of magnitude). This exceptionally broad dynamic range demonstrates the advantage of the one-pot assay approach with direct capture of the dual functional biotin-MB-AuNP via the strong biotin-neutravidin supramolecular interaction. Furthermore, we demonstrated the detection of miRNA-21 in spiked serum at clinically relevant concentrations. The miRNA biosensor displayed excellent analytical performance for the detection of miRNA and could provide a powerful and convenient tool for biomedical research and applications in cancer diagnostics.

  • 13.
    Ghani, Mozhdeh
    et al.
    Nanotechnology Institute, Amirkabir University of Technology, Tehran, Iran.
    Mak, Wing Cheung
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Cheung, Kwan Yee
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Medicine and Health Sciences.
    Montazer, M.
    Nanotechnology Institute, Amirkabir University of Technology, Tehran, Iran.
    Rezaei, B.
    Nanotechnology Institute, Amirkabir University of Technology, Tehran, Iran.
    Griffith, May
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Medicine and Health Sciences.
    Cross-linked superfine electrospun tragacanth-based biomaterial as scaffolds for tissue engineering2016In: European Cells and Materials, ISSN 1473-2262, E-ISSN 1473-2262, Vol. 31, no Suppl. 1, p. 204-204Article in journal (Refereed)
    Abstract [en]

    Natural polymer-based nanofibrous structures promote cell adhesion and proliferation due to their high surface area/volume ratio, high porosity, and similarity to native extracellular matrix in terms of both chemical composition and physical structure. Gum tragacanth (Tg) is a natural polysaccharides obtained from plants. It is a biocompatible, biodegradable and anionic polysaccharides that has been used extensively as an emulsifier in food and pharmaceutical industries. Despite, its good rheological properties and compatibility, the potential biomedical applications of Tg have not been fully investigated. The objective of the present study was to explore the feasibility of combining Tg with gelatin to fabricate a scaffold that serves as a simple collagen-glycosaminoglycans analog for tissue engineering applications, e.g. as a scaffold for human skin epithelial cells.

  • 14.
    Hatamie, Amir
    et al.
    Linköping University, Department of Science and Technology. Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Shahid Chamran University, Iran.
    Khan, Azam
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology. NED University of Engn and Technology, Pakistan.
    Golabi, Mohsen
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Beni, Valerio
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Mak, Wing Cheung
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Sadollah Khani, Azar
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology. Shahid Chamran University, Iran.
    Alnoor, Hatim
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Zargar, Behrooz
    Shahid Chamran University, Iran.
    Bano, Sumaira
    Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Nour, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Zinc Oxide Nanostructure-Modified Textile and Its Application to Biosensing, Photocatalysis, and as Antibacterial Material2015In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 31, no 39, p. 10913-10921Article in journal (Refereed)
    Abstract [en]

    Recently, one-dimensional nanostructures with different morphologies (such as nanowires, nanorods (NRs), and nanotubes) have become the focus of intensive research, because of their unique properties with potential applications. Among them, zinc oxide (ZnO) nanomaterials has been found to be highly attractive, because of the remarkable potential for applications in many different areas such as solar cells, sensors, piezoelectric devices, photodiode devices, sun screens, antireflection coatings, and photocatalysis. Here, we present an innovative approach to create a new modified textile by direct in situ growth of vertically aligned one-dimensional (1D) ZnO NRs onto textile surfaces, which can serve with potential for biosensing, photocatalysis, and antibacterial applications. ZnO NRs were grown by using a simple aqueous chemical growth method. Results from analyses such as X-ray diffraction (XRD) and scanning electron microscopy (SEM) revealed that the ZnO NRs were dispersed over the entire surface of the textile. We have demonstrated the following applications of these multifunctional textiles: (1) as a flexible working electrode for the detection of aldicarb (ALD) pesticide, (2) as a photo catalyst for the degradation of organic molecules (i.e., Methylene Blue and Congo Red), and (3) as antibacterial agents against Escherichia coli. The ZnO-based textile exhibited excellent photocatalytic and antibacterial activities, and it showed a promising sensing response. The combination of sensing, photo catalysis, and antibacterial properties provided by the ZnO NRs brings us closer to the concept of smart textiles for wearable sensing without a deodorant and antibacterial control. Perhaps the best known of the products that is available in markets for such purposes are textiles with silver nanoparticles. Our modified textile is thus providing acceptable antibacterial properties, compared to available commercial modified textiles.

  • 15.
    Jiang, Jie
    et al.
    National University of Singapore .
    Li, Xiaomin
    WinTech Nano-Technology Services Pte. Ltd, Singapore.
    Mak, Wing Cheung
    National University of Singapore .
    Trau, Dieter
    National University of Singapore .
    Integrated direct DNA/protein patterning and microfabrication by focused ion beam milling2008In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 20, no 9, p. 1636-1643Article in journal (Refereed)
    Abstract [en]

    Single and binary component patterning and integrated microfabrication of biomolecules, such as DNA and proteins, can be achieved by focused ion-beam (FIB) biolithography. Well-defined micropatterns are obtained by FIB milling on biomolecules immobilized on SiO2 wafers and protected by a thin Au film. The retention of biofunctionality is excellent (68–90%) and a feature size of down to 500 nm can be achieved for the patterns without significant loss of functionality.

  • 16.
    Jianhao, Bai
    et al.
    Division of Bioengineering, National University of Singapore, Singapore.
    Sebastian, Beyer
    Division of Bioengineering, National University of Singapore, Singapore.
    Wing Cheung, Mak
    Department of Chemistry, Hong Kong University of Science and Technology, Hong Kong SAR, P.R. China.
    Raj, Rajagopalan
    Department of Chemical & Biomolecular Engineering, National University of Singapore, Singapore.
    Dieter, Trau
    Department of Chemical & Biomolecular Engineering, National University of Singapore, Singapore and .
    Inwards buildup of concentric polymer layers: A method for biomolecule encapsulation and microcapsule encoding2010In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 49, no 330, p. 5189-5193Article in journal (Refereed)
    Abstract [en]

    Encoding by encapsulation: A polymeric shell fabrication approach combines biomolecule encapsulation with encoding. Striated polymeric shells, fabricated through an inwards diffusion of poly(allylamine) into the matrices of agarose microbeads, serves to encapsulate the biomolecules within the microcapsule. Encoding is performed through the color and/or thickness permutation of the striated polymeric shells (see picture).

  • 17.
    Kei Lai, Kwok
    et al.
    Hong Kong University of Science and Technology, Peoples R China .
    Renneberg, Reinhard
    Hong Kong University of Science and Technology, Peoples R China .
    Cheung Mak, Wing
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Bioinspired protein microparticles fabrication by peptide mediated disulfide interchange2014In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, no 23, p. 11802-11810Article in journal (Refereed)
    Abstract [en]

    In this article, we report an innovative green chemistry approach for the fabrication of protein microparticles based on peptide mediated disulfide interchange reactions. The concept is based on using a redox reactive peptide, glutathione, as a natural crosslink reagent triggering the formation of intermolecular disulfide bonds between adjacent protein molecules leading to the assembly of protein molecules within a CaCO3 template into a microparticle structure. The CaCO3 template is highly biocompatible and is completely removed by simply adjusting the solution to pH 5.0, leaving behind the pure protein microparticles. Moreover, the GSH is only involved in the intermediate step without being incorporated into the resulting protein microparticles, therefore producing protein microparticles composed of purely protein molecules. This technology provides a simple and robust method to fabricate protein microparticles under physiological aqueous conditions, and more importantly avoiding the extensive use of synthetic chemical crosslinking reagents. We have further demonstrated that this method is versatile to fabricate microparticles with various proteins such as BSA, enzymes and antibodies. The biological functions such as catalytic properties and affinity interactions of the resulting protein microparticles are highly conserved which demonstrate the potential applications of the protein microparticles in the area of biocatalysis, bioseparation and targeted drug delivery.

  • 18.
    Kor, Kamalodin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Zarei, Kobra
    School of Chemistry, Damghan University, Damghan, Iran.
    Atabati, Morteza
    School of Chemistry, Damghan University, Damghan, Iran.
    Beni, Valerio
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Mak, Wing Cheung
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Structurally responsive oligonucleotide-based single-probe lateral-flow test for detection of miRNA-21 mimics2016In: Analytical and Bioanalytical Chemistry, ISSN 1618-2642, E-ISSN 1618-2650, Vol. 408, no 5, p. 1475-1485Article in journal (Refereed)
    Abstract [en]

    A single-probe strip test for the rapid and sensitive detection of miRNA-21 mimics is reported herein. Highly specific structurally responsive bi-functional, thiol and biotin, DNA/LNA oligonucleotide probes (molecular beacons-MB) were designed and conjugated with gold nanoparticles (AuNPs) (i.e. biotin-MB-AuNPs). The proposed design had the ability to modulate the accessibility of the biotin group as a function of the presence of a miRNA target allowing the interaction of the boilable with the streptavidin test zone only in the presence of the miRNA-21 mimics. For quantitative evaluation, images of the strip tests were recorded using a flatbed scanner (Epson Perfection V370 Photo). The colour intensities of the test zones of the strip tests were analysed with the ImageJ software (Scion Corp., USA) and quantified as a function of pixel intensity. The response of the strip test was linear over the range 0.5 to 20 nM miRNA-21 (limit of detection of 115 pM) and showed good reproducibility (intra and inter CVs below 8 %); furthermore, the assay was shown to be highly selective, discriminating other interference miRNAs mimics (e.g. miRNA-221 and miRNA-205). Finally, the proposed strip test was used for detection of miRNA-21 mimics in spiked serum samples, demonstrating its potential for point-of-care clinical applications. Main advantages of the single-probe strip test design are its versatility, simplicity and robustness, which can be easily extended to other miRNA targets by tuning the sequence of the single probe. Furthermore, the use of the structurally responsive single probe is particularly relevant in the case of short-length targets, such as miRNA, whereas a conventional sandwich approach might require a careful control of assay conditions such as hybridization temperature and salt concentration

  • 19.
    Lademann, J.
    et al.
    Charite University of Medical Berlin, Germany.
    Richter, H.
    Charite University of Medical Berlin, Germany.
    Knorr, F.
    Charite University of Medical Berlin, Germany.
    Patzelt, A.
    Charite University of Medical Berlin, Germany.
    Darvin, M. E.
    Charite University of Medical Berlin, Germany.
    Ruehl, E.
    Free University of Berlin, Germany.
    Cheung, Kwan Yee
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Medicine and Health Sciences.
    Lai, K. K.
    Hong Kong University of Science and Technology, Peoples R China.
    Renneberg, R.
    Hong Kong University of Science and Technology, Peoples R China.
    Mak, Wing Cheung
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering. Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Triggered release of model drug from AuNP-doped BSA nanocarriers in hair follicles using IRA radiation2016In: Acta Biomaterialia, ISSN 1742-7061, E-ISSN 1878-7568, Vol. 30, p. 388-396Article in journal (Refereed)
    Abstract [en]

    Recent advances in the field of dermatotherapy have resulted in research efforts focusing on the use of particle-based drug delivery systems for the stimuli-responsive release of drugs in the skin and skin appendages, i.e. hair follicles and sebaceous glands. However, effective and innocuous trigger mechanisms which result in the release of the drugs from the nanocarriers upon reaching the target structures are still lacking. For the first time, the present study demonstrated the photo-activated release of the model drug fluorescein isothiocyanate (FITC) from topically applied gold nanoparticle-doped bovine serum albumin (AuNPs-doped BSA) particles (approx. 545 nm) using water-filtered infrared A (IRA) radiation in the hair follicles of an ex vivo porcine skin model. The IRA radiation-induced plasmonic heating of the AuNPs results in the partial decomposition or opening of the albumin particles and release the model drug, while control particles without AuNPs show insignificant release. The results demonstrate the feasibility of using IRA radiation to induce release of encapsulated drugs from plasmonic nanocarriers for the targeting of follicular structures. However, the risk of radiation-induced skin damage subsequent to repeated applications of high infrared dosages may be significant. Future studies should aim at determining the suitability of lower infrared A dosages, such as for medical treatment regimens which may necessitate repeated exposure to therapeutics. Statement of significance Follicular targeting using nanocarriers is of increasing importance in the prophylaxis and treatment of dermatological or other diseases. For the first time, the present study demonstrated the photo activated release of the model drug fluorescein isothiocyanate (FITC) from topically applied gold nanoparticle-doped bovine serum albumin (AuNPs-doped BSA) particles using water-filtered infrared A (IRA) radiation in the hair follicles of an ex vivo porcine skin model. The results demonstrate the feasibility of using wIRA radiation to induce release of encapsulated drugs for the targeting of follicular structures, and provide a new vision on the development of optically addressable delivery systems for controlled release of drugs in the skin and skin appendages, i.e. hair follicles and sebaceous glands. (C) 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  • 20.
    Lademann, Jürgen
    et al.
    Charité - Universitätsmedizin Berlin, Germany.
    Richter, Heike
    Charité - Universitätsmedizin Berlin, Germany.
    Meinke, Martina C.
    Charité - Universitätsmedizin Berlin, Germany.
    Lange-Asschenfeldt, Bernhard
    Charité - Universitätsmedizin Berlin, Germany.
    Antoniou, Constantinos
    University of Athens, A. Sygros Hospital, Greece.
    Mak, Wing Cheung
    Hong Kong University of Science and Technology, China .
    Renneberg, Reinhard
    Hong Kong University of Science and Technology, China.
    Sterry, Wolfram
    Charité - Universitätsmedizin Berlin, Germany.
    Patzelt, Alexa
    Charité - Universitätsmedizin Berlin, Germany.
    Drug delivery with topically applied nanoparticles: science fiction or reality2013In: Skin Pharmacology and Physiology, ISSN 1660-5527, E-ISSN 1660-5535, Vol. 26, no 4-6, p. 227-233Article in journal (Refereed)
    Abstract [en]

    The efficacy of topically applied drugs is determined by their action mechanism and their potential capacity of passing the skin barrier. Nanoparticles are assumed to be efficient carrier systems for drug delivery through the skin barrier. For flexible nanoparticles like liposomes, this effect has been well demonstrated. The penetration properties of solid nanoparticles are currently under intensive investigation. The crucial advantage of nanoparticles over non-particulate substances is their capability to penetrate deeply into the hair follicles where they can be stored for several days. There is no evidence, yet, that solid particles ≥40 nm are capable of passing through the healthy skin barrier. Therefore and in spite of the long-standing research efforts in this field, commercially available solid nanoparticle-based products for drug delivery through the healthy skin are still missing. Nevertheless, the prospects for the clinical use of nanoparticles in drug delivery are tremendous. They can be designed as transport systems delivering drugs efficiently into the hair follicles in the vicinity of specific target structures. Once deposited at these structures, specific signals might trigger the release of the drugs and exert their effects on the target cells. In this article, examples of such triggered drug release are presented.

  • 21.
    Lai, Kwok Kei
    et al.
    Hong Kong University of Science and Technology, Clear Water Bay, P. R. China .
    Renneberg, Reinhard
    Hong Kong University of Science and Technology, Clear Water Bay, P. R. China .
    Mak, Wing Cheung
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    High efficiency single-step biomaterial-based microparticle fabrication via template-directed supramolecular coordination chemistry2016In: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, Vol. 18, no 6, p. 1715-1723Article in journal (Refereed)
    Abstract [en]

    Biomaterial-based microparticles have attracted much attention for medical and biological applications such as pharmaceutics, bioseparation and cosmetics. Emerging technologies enable versatile and facile fabrication of microparticles, with key features being purity, precise size control, mild preparation conditions and minimal processing. Here, an innovative approach combining template synthesis, biomolecule assembly and partial-purification within a single step for high efficiency fabrication of pure biomaterial-based microparticles is reported. This concept is based on facile co-precipitation of biomolecules within CaCO3 templates and simultaneous crosslinking of entrapped biomolecules via Ca2+ driven supramolecular coordination chemistry, followed by template removal. Carbohydrate (alginate) and proteins (casein and fresh milk) are used as models of biomolecules. The process driven by selective crosslinking automatically excludes non-specific materials from the template and thus provides the additional function of partial-purification, as demonstrated using highly complexed fresh milk. This green approach to fabrication of biomaterial-based microparticles offers three critical advantages (i) mild conditions to preserve the chemical and secondary structures of biomolecules; (ii) single processing step to facilitate scale-up production; and (iii) partial-purification without the need for upstream raw material purification. This innovative approach not only addresses fundamental issues in fabrication techniques, but also marks progress in energy and environmental conservation during manufacturing processes.

  • 22.
    Liu, Yu
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering. Sichuan Agriculture University, Peoples R China.
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Zhao, Maojun
    Sichuan Agriculture University, Peoples R China.
    Mak, Wing Cheung
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Processable enzyme-hybrid conductive polymer composites for electrochemical biosensing2018In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 100, p. 374-381Article in journal (Refereed)
    Abstract [en]

    A new approach for the facile fabrication of electrochemical biosensors using a biohybrid conducting polymer was demonstrated using glucose oxidase (GOx) and poly (3, 4-ethylenedioxythiophene) (PEDOT) as a model. The biohybrid conducting polymer was prepared based on a template-assisted chemical polymerisation leading to the formation of PEDOT microspheres (PEDOT-MSs), followed by in-situ deposition of platinum nanoparticles (PtNPs) and electrostatic immobilisation of glucose oxidase (GOx) to form water processable GOx-PtNPs-PEDOT-MSs. The morphology, chemical composition and electrochemical performance of the GOx-PtNPs-PEDOT-MS-based glucose biosensor were characterised using scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), Fourier transform infrared (FTIR) spectroscopy, zeta potential and electrochemical measurements, respectively. The biosensor delivered a linear response for glucose over the range 0.1-10 mM (R-2 = 0.9855) with a sensitivity of 116.25 mu A mM(-1) cm(-2), and limit of detection of 1.55 mu M (3 x SD/sensitivity). The sensitivity of the developed PEDOT-MS based biosensor is significantly higher (2.7 times) than the best reported PEDOT-based glucose biosensor in the literature. The apparent Michaelis Menten constant (K-m(app)) of the GOx-PtNPs-PEDOT-MS-based biosensors was calculated as 7.3 mM. Moreover, the biosensor exhibited good storage stability, retaining 97% of its sensitivity after 12 days storage. This new bio-hybrid conducting polymer combines the advantages of micro-structured morphology, compatibility with large-scale manufacturing processes, and intrinsic biocatalytic activity and conductivity, thus demonstrating its potential as a convenient material for printed bioelectronics and sensors.

  • 23.
    Liu, Yu
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering. Sichuan Agr Univ, Peoples R China.
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Zhao, Maojun
    Sichuan Agr Univ, Peoples R China.
    Wing Cheung, Mak
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Facile synthesis of highly processable and water dispersible polypyrrole and poly(3,4-ethylenedioxythiophene) microspheres for enhanced supercapacitive performance2018In: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 99, p. 332-339Article in journal (Refereed)
    Abstract [en]

    Much recent work has focused on improving the processibility and electrocapacitive performance of conducting polymer-based materials for energy related applications. The key mechanism of conducting polymers as supercapacitor materials is driven by the rapid charging and discharging processes that involve mass transport of the counter ions insertion/ejection within the polymer structure, where ion diffusion is usually the limiting step on the efficiency of the conducting polymer capacitor. Here, we report a facile method for the green fabrication of polypyrrole microspheres (PPy-MSs) and poly (3, 4-ethylenedioxythiophene) microspheres (PEDOT-MSs) with good processability, intact morphology and large active surface for enhanced ion interchange processes, without using surfactant and highly irritant or toxic organic solvents during the synthetic process. The structure and morphology of the PPy-MSs and PEDOT-MSs were characterized by means of SEM, EDX, TEM and FTIR. Both PPy-MSs and PEDOT-MSs showed intact microsphere structures with greatly improved water dispersity and processability. More importantly, facilated by the large active surface and inter-microsphere space for ions diffusion, both the PPy-MSs and PEDOT-MSs showed a signiciantly enhanced electrical capacitive performance of 242 F g(-1) and 91.2 F g(-1), repsectively (i.e. 10 and 1.51 times in specific capacitance than the randomly structured PPy and PEDOT). This innovative approach not only addresses fundamental issues in fabrication of high performance processable microstructured conducting polymers, but also makes progress in delivering water processable conducting polymers that could be potentially used for fabrication of printed electronic devices.

  • 24.
    Mak, Wing Cheung
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Biomedical Nanosensors, Joseph Irudayaraj, Pan Stanford Publishing, ISBN: 9789814303033 Taylor & Francis Group, UK, 2013, 384, 95 GBP2013In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 44, p. 136-137Article, book review (Other academic)
  • 25.
    Mak, Wing Cheung
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Biosensor technologies for agriculture and environment - opportunities and challenges2017In: Proceedings of the 8th Nordic Feed Science Conference, Uppsala, Sweden, 13-14 June 2017 / [ed] Udén, P.; Eriksson, T.; Spörndly, R.; Rustas, B. O.; Kasmaei, K. M.; Liljeholm, M., Uppsala: Swedish University of Agricultural Sciences, Department of Animal Nutrition and Management , 2017, p. 38-41Conference paper (Refereed)
    Abstract [en]

    This paper presents the general principles of various biosensor systems, reviews current biosensor technologies for agricultural and environmental monitoring, and discusses their opportunities and challenges. Advances in biosensor technologies could provide a useful analytical tools for agricultural monitoring, particularly due to their rapid response, relatively low operational cost and portability for field/farm application. The promise, demonstrated by various examples of biosensor technologies, is very appealing. However, there are still many hurdles to bring commercial agricultural biosensors into real practice.

  • 26.
    Mak, Wing Cheung
    et al.
    Hong Kong University of Science and Technology, Hong Kong, China .
    Bai, Jianhao
    National University of Singapore.
    Chang, Xiang Yun
    National University of Singapore.
    Trau, Dieter
    National University of Singapore.
    Matrix-assisted colloidosome reverse-phase layer-by-layer encapsulating biomolecules in hydrogel microcapsules with extremely high efficiency and retention stability2009In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 25, no 2, p. 769-775Article in journal (Refereed)
    Abstract [en]

    The layer-by-layer (LbL) polyelectrolyte self-assembly encapsulation method has attracted much interest because of its versatility to use various polymers for capsule formation, ability to encapsulate different templates, and capability to control capsule permeability. Traditionally, the LbL method was performed in water as solvent and limited to poorly or non-water-soluble templates. Using the matrix-assisted LbL method, complex mixtures of water-soluble proteins or DNA could be encapsulated within agarose microbeads templates but leakage of biomolecules into the water phase during the LbL process results in low encapsulation efficiency. Recently, the reverse-phase LbL (RP-LbL) method was introduced to perform LbL and encapsulation of water-soluble templates in organic solvents, thus preventing the templates from dissolving and allowing high encapsulation efficiency. However, encapsulation of complex mixtures of biomolecules or other substances with quantitative encapsulation efficiency remained impossible. Here we present a new approach for encapsulation of biomolecules or complex mixtures thereof with almost 100% encapsulation efficiency. The ability of our method to achieve high encapsulation efficiency arises from the combination of two strategies. (1) Using microparticles as surface stabilizer to create stable biomolecule-loaded hydrogel microbeads, termed matrix-assisted colloidosome (MAC), that are able to disperse in oil and organic solvents. (2) Using the RP-LbL method to fabricate polymeric capsule “membranes”, thereby preventing diffusion of the highly water-soluble biomolecules. Using an oil phase during emulsification and an organic solvent phase during encapsulation could completely prevent leakage of water-soluble biomolecules and almost 100% encapsulation efficiency is achieved. Microcapsules fabricated with our method retained nearly 100% of encapsulated proteins during a 7 day incubation period in water. The method was demonstrated on model proteins and may be extended to other biomolecules or mixtures. Our method is a valuable addition to the family of encapsulation techniques and can significantly contribute to the fields of bioreactors and bioanalytical microcapsules.

  • 27.
    Mak, Wing Cheung
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Beni, Valerio
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Lateral-flow technology: from visual to instrumental.2016In: TrAC. Trends in analytical chemistry, ISSN 0165-9936, E-ISSN 1879-3142, Vol. 79, no SI, p. 297-305Article in journal (Refereed)
    Abstract [en]

    Lateral-flow tests were first launched commercially in 1984, as a simple urine-based pregnancy test for home use. The simplicity of the visual readout delivered by the basic lateral-flow format proved to be a very popular. However, the recent apparently unstoppable trend towards portable and wearable technology is driving the lateral-flow strip towards an industrial interface that will enable it to interface with big data and expert systems, and where ready transmission of data is essential. In this review, we chart the inevitable evolution of the visually-read lateral-flow strip to more advanced instrumented versions and consider the future of this very flexible approach to delivering simple affinity assays. We examine recent labelling strategies, the relative merits of optical and electrochemical transducers and explore the evolution of recognition elements that are now being incorporated into these systems.

  • 28.
    Mak, Wing Cheung
    et al.
    Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
    Chan, Chiyui
    Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
    Barford, John
    Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
    Renneberg, Reinhard
    Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
    Biosensor for rapid phosphate monitoring in sequencing batch reactor (SBR) system2003In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 19, no 3, p. 233-237Article in journal (Refereed)
    Abstract [en]

    A thick-film phosphate biosensor based on hydrogel immobilized pyruvate oxidase (POD) has been developed for rapid phosphate process control monitoring in an experimental sequencing batch reactor (SBR) system. We have employed a phosphate biosensor in an off-line monitoring of phosphate concentrations in a bench scale SBR. Measurements with biosensor show a good correlation (r2=0.98) with those of commercial colorimetric phosphate testing kits. The signal response time was 1 min with a detection limit of 5 microM. The biosensor method showed a good operational stability, needed less experimental procedures and a small sample size (approximately 20 microl). This allows its practical application for rapid phosphate measurements to obtain real time process data in a SBR system.

  • 29.
    Mak, Wing Cheung
    et al.
    National University of Singapore.
    Cheung, Kwan Yee
    National University of Singapore.
    Trau, Dieter
    National University of Singapore.
    Diffusion controlled and temperature stable microcapsule reaction compartments for high throughput microcapsule-PCR2008In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 18, no 19, p. 2930-2937Article in journal (Refereed)
    Abstract [en]

    A novel approach to perform a high number of individual polymerase chain reactions (PCR) in microcapsule reaction compartments, termed “Microcapsule-PCR” was developed. Temperature stable microcapsules with a selective permeable capsule wall were constructed by matrix-assisted layer-by-layer (LbL) Encapsulation technique. During the PCR, small molecular weight building blocks – nucleotides (dNTPs) were supplied externally and diffuse through the permeable capsule wall into the interior, while the resulted high molecular weight PCR products were accumulated within the microcapsule. Microcapsules (∼110.8 µm average diameter) filled with a PCR reaction mixture were constructed by an emulsion technique having a 2% agarose core and a capsule formed by LbL coating with poly(allylamine-hydrochloride) and poly(4-styrene-sulfonate). An encapsulation efficiency of 47% (measured for primer-FITC (22 bases)) and 98% PCR efficiency was achieved. Microcapsules formed by eight layers of polyelectrolyte and subjected to PCR cycling (up to 95 °C) demonstrated good temperature stability without any significantly changes in DNA retention yield and microcapsule morphology. A multiplex Microcapsule-PCR experiment demonstrated that microcapsules are individual compartment and do not exchange templates or primers between microcapsules during PCR cycling.

  • 30.
    Mak, Wing Cheung
    et al.
    Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
    Cheung, Kwan Yee
    Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
    Trau, Dieter
    National University of Singapore.
    Warsinke, Axel
    University of Potsdam, Golm, Germany.
    Scheller, Frieder
    University of Potsdam, Golm, Germany.
    Renneberg, Reinhard
    Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
    Electrochemical bioassay utilizing encapsulated electrochemical active microcrystal biolabels2005In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 77, no 9, p. 2835-2841Article in journal (Refereed)
    Abstract [en]

    A new approach to perform electrochemical immunoassay based on the utilization of encapsulated microcrystal was developed. The microcrystal labels create a “supernova effect” upon exposure to a desired releasing agent. The microcrystal cores dissolve, and large amounts of signal-generating molecules diffuse across the capsule wall into the outer environment. Layer-by-Layer (LbL) technology was employed for the encapsulation of electrochemical signal-generating microcrystals (ferrocene microcrystals). The encapsulated microcrystals were conjugated with antibody molecules through the adsorption process. The biofunctionalized microcrystals were utilized as a probe for immunoassays. The microcrystal-based label system provided a high-signal molecule to antibody (S/P) ratio of 104−105. Microcrystal biolabels with different antibody surface coverage (1.60−5.05 mg m-2) were subjected to a solid-phase immunoassay for the detection of mouse immunoglobulin G (M-IgG) molecules. The microcrystal-based immunoassay for the detection of M-IgG performed with microcrystals having antibody surface coverage of 5.05 mg m-2 showed a sensitivity of 3.93 nA μg-1 L-1 with a detection limit of 2.82 μg L-1.

  • 31.
    Mak, Wing Cheung
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Cheung, K.Y.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Medicine and Health Sciences.
    Orban, Jenny
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Lee, C-J
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Griffith, May
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Medicine and Health Sciences.
    Theranostic Contact Lens for Modulation and Detection of Viral Infection2017In: 26th Anniversary World Congress on Biosensors (Biosensors), Elsevier, 2017Conference paper (Other academic)
  • 32.
    Mak, Wing Cheung
    et al.
    Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China.
    Georgieva, Radostina
    Berlin-Brandenburg Center of Regenerative Therapies, Charité-Universitätsmedizin Berlin, Germany.
    Renneberg, Reinhard
    Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China.
    Bäumler, Hans
    Berlin-Brandenburg Center of Regenerative Therapies, Charité-Universitätsmedizin Berlin, Germany.
    Protein particles formed by protein activation and spontaneous self-assembly2010In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 20, no 23, p. 4139-4144Article in journal (Refereed)
    Abstract [en]

    In this article, a non-chemical crosslinking method is used to produce pure protein microparticles with an innovative approach, so-called protein activation spontaneous and self-assembly (PASS). The fabrication of protein microparticles is based on the idea of using the internal disulfide bridges within protein molecules as molecular linkers to assemble protein molecules into a microparticle form. The assembly process is triggered by an activating reagent–dithiothreitol (DTT), which only involved in the intermediate step without being incorporated into the resulting protein microparticles. Conventional protein microparticle fabrication methods usually involve emulsification process and chemical crosslink reactions using amine reactive reagents such as glutaraldehdye or EDC/NHS. The resulting protein microparticles are usually having various size distributions. Most importantly crosslinking reactions using amine reactive reagents will result in producing protein microparticles with undesired properties such as auto-fluorescence and high toxicity. In contrast to the conventional methods, our technology provides a simple and robust method to produce highly homogeneous, stable and non-fluorescence pure protein microparticles under mild conditions at physiological pH and temperature. The protein microparticles are found to be biodegradable, non-toxic to MDCK cells and with preserved biological activities. Results on the cytotoxcity study and enzyme function demonstrate the potential applications of the protein microparticles in the area of pharmaceutics and analytical chemistry.

  • 33.
    Mak, Wing Cheung
    et al.
    Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR.
    Li, Yongjun
    Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR.
    Lau, Wan Keung
    Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR.
    Trau, Dieter
    Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR.
    Nanoengineered encapsulation of mediator microcrystals and their use as a non-metallic label system for the silver enhancement technique2004In: Electroanalysis, ISSN 1040-0397, E-ISSN 1521-4109, Vol. 16, no 1-2, p. 156-160Article in journal (Refereed)
    Abstract [en]

    We report on the nanoengineered encapsulation and functionalization of mediator microcrystals and their use as a non-metallic bioassay label system for the silver enhancement technology. Mediator microcrystals were encapsulated and functionalized by using a Layer-by-Layer (LbL) based approach. This is a generic way to transform most low-soluble mediators (e.g., ferroceneacetic acid) into a label for electrochemical bioassays. Instead of using conventional gold particles, encapsulated mediator microcrystals are used as the primary label for the silver enhancement technique. After the biorecognition reaction the unbound labels were separated and a silver(I) ion solution was added. The mediator reduces silver ions into metallic silver and the mediator microcrystal was transformed into a silver particle. Consecutively a reducing agent was added leading to a further silver growth, representing the silver enhancement step. A large amount of silver was developed from the mediator, resulting in signal amplification. The amount of developed silver was studied in a bioassay and was found proportional to the analyte concentration.

  • 34.
    Mak, Wing Cheung
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering. Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Magne, B.
    Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Cheung, Kitt
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Medicine and Health Sciences.
    Atanasova, Diana
    Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Griffith, May
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Medicine and Health Sciences. University of Montreal, Canada.
    Thermo-rheological responsive microcapsules for time-dependent controlled release of human mesenchymal stromal cells2017In: Biomaterials Science, ISSN 2047-4830, E-ISSN 2047-4849, Vol. 5, no 11, p. 2241-2250Article in journal (Refereed)
    Abstract [en]

    Human mesenchymal stromal cells (hMSCs) are adult-source cells that have been extensively evaluated for cell-based therapies. hMSCs delivered by intravascular injection have been reported to accumulate at the sites of injury to promote tissue repair and can also be employed as vectors for the delivery of therapeutic genes. However, the full potential of hMSCs remains limited as the cells are lost after injection due to anoikis and the adverse pathologic environment. Encapsulation of cells has been proposed as a means of increasing cell viability. However, controlling the release of therapeutic cells over time to target tissue still remains a challenge today. Here, we report the design and development of thermo-rheological responsive hydrogels that allow for precise, time dependent controlled-release of hMSCs. The encapsulated hMSCs retained good viability from 76% to 87% dependent upon the hydrogel compositions. We demonstrated the design of different blended hydrogel composites with modulated strength (S parameter) and looseness of hydrogel networks (N parameter) to control the release of hMSCs from thermoresponsive hydrogel capsules. We further showed the feasibility for controlled-release of encapsulated hMSCs within 3D matrix scaffolds. We reported for the first time by a systematic analysis that there is a direct correlation between the thermo-rheological properties associated with the degradation of the hydrogel composite and the cell release kinetics. This work therefore provides new insights into the further development of smart carrier systems for stem cell therapy.

  • 35.
    Mak, Wing Cheung
    et al.
    Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
    Ng, Yuk Mui
    Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
    Chan, Chiyui
    Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
    Kwong, Wai Kuen
    Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
    Renneberg, Reinhard
    Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
    Novel biosensors for quantitative phytic acid and phytase measurement2004In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 19, no 9, p. 1029-1035Article in journal (Refereed)
    Abstract [en]

    Phytase (EC 3.1.3.26) and phytic acid (myo-inositol hexaphosphate) play an important environmental role in poultry industry and have a health aspect in food industry. Novel biosensors have been developed for simple, one step quantitative phytic acid and phytase detection. A system based on the sequentially acting enzyme phytase and pyruvate oxidase (POD) was employed for the development of phytase and phytic acid biosensors. Poly(carbamoylsulphonate) (PCS) hydrogel immobilized POD electrode was applied for the detection of phytase. It was based on the indication of phosphate ions produced by the hydrolysis of phytic acid. The phytase biosensor showed a linear response ranging from 0.5 to 6.0 units/ml. A bi-enzyme sensor based on co-immobilization of phytase and POD was developed for the detection of phytic acid on the basis of amperometric detection of the enzymatically-generated hydrogen peroxide at 0.6 V versus Ag/AgCl. It showed a linear response ranging from 0.2 to 2.0 mM with a detection limit of 0.002 mM.

  • 36.
    Mak, Wing Cheung
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Olesen, Kim
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Medicine and Health Sciences.
    Sivlér, Petter
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Medicine and Health Sciences.
    Lee, Chyan-Jang
    Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Moreno-Jimenez, Ines
    Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Medicine and Health Sciences. Bone & Joint Research Group, Stem Cells & Regeneration Institute of Developmental Sciences, Southampton General Hospital, UK.
    Edin, Joel
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Medicine and Health Sciences.
    Courtman, D.
    Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Canada.
    Skog, Mårten
    Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Griffith, May
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Medicine and Health Sciences.
    Correction: W.C. Mak, et al. Controlled Delivery of Human Cells by Temperature Responsive Microcapsules. J. Funct. Biomater. 2015, 6, 439-4532018In: Journal of Functional Biomaterials, ISSN 2079-4983, E-ISSN 2079-4983, Vol. 9, no 2, article id 26Article in journal (Other academic)
  • 37.
    Mak, Wing Cheung
    et al.
    Hong Kong University of Science and Technology, Hong Kong, China.
    Richter, Heike
    Center of Experimental and Cutaneous Physiology, Department of Dematology, Venerology and Allergology, Charité Universitätsmedizin Berlin, Germany.
    Patzelt, Alexa
    Center of Experimental and Cutaneous Physiology, Department of Dematology, Venerology and Allergology, Charité Universitätsmedizin Berlin, Germany.
    Sterry, Wolfram
    Center of Experimental and Cutaneous Physiology, Department of Dematology, Venerology and Allergology, Charité Universitätsmedizin Berlin, Germany.
    Lai, Kwok Kei
    Hong Kong University of Science and Technology, Hong Kong, China.
    Renneberg, Reinhard
    Hong Kong University of Science and Technology, Hong Kong, China.
    Lademann, Jürgen
    Center of Experimental and Cutaneous Physiology, Department of Dematology, Venerology and Allergology, Charité Universitätsmedizin Berlin, Germany.
    Drug delivery into the skin by degradable particles2011In: European journal of pharmaceutics and biopharmaceutics, ISSN 0939-6411, E-ISSN 1873-3441, Vol. 79, no 1, p. 23-27Article in journal (Refereed)
    Abstract [en]

    Recently, it was demonstrated that particles could be utilized as carrier systems for drugs into the hair follicles. In the present study, a two-component drug delivery system is presented consisting of degradable particles loaded with fluorescein isothiocyanate and a separate protease formulation for degradation. The particles were applied alone, 30 min previous to the protease application and simultaneously with the protease onto porcine skin. Subsequently, biopsies were removed, and the penetration depths of the particles were analyzed using laser scanning microscopy.

    The obtained results demonstrate that the particles alone achieved a penetration depth of around 900 μm. Similar results were obtained for the successive application of particles and protease, whereas a release of the fluorescent dye was only observed in the upper 250 μm corresponding to the penetration depth of the protease. In the case of the simultaneous application, the particles were partly dissolved before application, leading to a reduced particle size and diminished penetration depth.

    The results revealed that degradable particles are a promising tool for drug delivery into the skin.

  • 38.
    Mak, Wing Cheung
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Selegård, Robert
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, The Institute of Technology.
    Garbrecht, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Aili, Daniel
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, The Institute of Technology.
    Probing Zinc-Protein-Chelant Interactions using Gold Nanoparticles Functionalized with Zinc-Responsive Polypeptides2014In: Particle & particle systems characterization, ISSN 0934-0866, E-ISSN 1521-4117, Vol. 31, no 11, p. 1127-1133Article in journal (Refereed)
    Abstract [en]

    The coordination of zinc by proteins and various other organic molecules is essential for numerous biological processes, such as in enzymatic catalysis, metabolism and signal transduction. Presence of small molecular chelants can have a profound effect on the bioavailability of zinc and affect critical Zn2+-protein interactions. Zn2+ chelators are also emerging therapeutics for Alzheimer’s diseases because of their preventive effect on zinc promoted amyloid formation. Despite the importance of zinc-protein-chelant interactions in biology and medicine, probing such interactions is  challenging. Here, we introduce an innovative approach for real-time characterization of zinc-protein-chelant interactions using gold nanoparticles (AuNPs) functionalized with a zinc-responsive protein mimetic polypeptide. The peptide functionalized AuNPs aggregate extensively in the presence of Zn2+, triggered by specific Zn2+-mediated polypeptide dimerization and folding, causing a massive red shift of the plasmon band. Chelants affects the Zn2+- polypeptide interaction and thus the aggregation differently depending on their concentrations, zincbinding affinities and coordination numbers, which affect the position of the plasmon band. This system is a simple and powerful tool that provides extensive information about the interactions of chelants in the formation of Zn2+ coordination complexes and is an interesting platform for development of bioanalytical techniques and characterization of chelation-based therapeutics.

  • 39.
    Mak, Wing Cheung
    et al.
    Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China.
    Sin, K. K.
    DNA SuperNova Limited, Hong Kong, China.
    Chan, Cangel Pui Yee
    Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong, China.
    Wong, Ling Wai
    DNA SuperNova Limited, Hong Kong, China.
    Renneberg, Reinhard
    Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China.
    Biofunctionalized indigo-nanoparticles as biolabels for the generation of precipitated visible signal in immunodipsticks2011In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 26, no 7, p. 3148-3153Article in journal (Refereed)
    Abstract [en]

    A novel class of organic nanoparticles as biolabels that can generate an instant visible signal was applied to immunodipsticks. A new principle for signal generation based on hydrolysis of colourless signal precursor molecules to produce coloured signal molecules followed by signal precipitation and localization was demonstrated. The nanoparticle biolabels were applied to sandwich immunoassays for the detection of mouse immunoglobulin G (M IgG). In the presence of M IgG, a nanoparticle-immunocomplex was formed and bound on the test zone immobilized with goat anti M IgG (Gt α M IgG). A blue line was developed on the test zone upon the addition of a signal developing reagent. An optical signal could be simply assessed using naked eyes or quantified using a reading device. The lowest visible signal that could be observed using naked eyes was found to be 1.25 μg L−1 M IgG. The nanoparticle biolabel also showed a better sensitivity (signal-to-noise ratio) compared with the conventional colloidal gold biolabel. This novel class of organic nanoparticles offers an alternative biolabel system for the development of point-of-care immunodipsticks.

  • 40.
    Mak, Wing Cheung
    et al.
    Hong Kong University of Science and Technology, Hong Kong, China.
    Sum, Ka Wai
    Hong Kong University of Science and Technology, Hong Kong, China.
    Trau, Dieter
    Hong Kong University of Science and Technology, Hong Kong, China.
    Renneberg, Reinhard
    Hong Kong University of Science and Technology, Hong Kong, China.
    Nanoscale surface engineered living cells with extended substrate spectrum2004In: IEE Proceedings - Nanobiotechnology, ISSN 1478-1581, Vol. 151, no 2, p. 67-72Article in journal (Refereed)
    Abstract [en]

    We report on cell surface engineering of living microorganisms by using Layer-by-Layer (LbL) technology to extend the substrate spectrum. The yeast Arxula adeninivorans LS3 (Arxula) was employed as a model organism and biological template. By using LbL technology, Arxula cells were encapsulated by polyelectrolyte and enzyme layers. The biological activity of the Arxula was retained after the encapsulation process. The polymeric capsule surrounding the Arxula provides a stable interface for surface engineering of living cells. LbL of polyelectrolytes followed by an enzyme layer of lactate oxidase were assembled. The outer enzyme layer provides an additional biological function for Arxula to convert the unfavourable substrate lactate into the favourable substrate pyruvate, thus extending the substrate spectrum of the organism. Moreover, capsule stability and enzyme conjugate stability of the surface engineered Arxula were studied.

  • 41.
    Mak, Wing Cheung
    et al.
    National University of Singapore.
    Yangzhong, Hong
    National University of Singapore.
    Trau, Dieter
    National University of Singapore.
    Real time observation of diffusion and bioaffinity binding processes in single polyelectrolyte-coated microcapsules: A fluorescence-based approach2007In: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 60, no 1, p. 125-130Article in journal (Refereed)
    Abstract [en]

    We report on using fluorescence microscopy to study, visualize and determine the diffusion phenomena into and bioaffinity binding within single microcapsules in real time by using biotin–fluorescein as diffusive species and encapsulated avidin as binding partner. Microcapsules were constructed by entrapment of avidin within an agarose matrix and encapsulated with polyelectrolyte layers by Layer-by-Layer (LbL) polyelectrolyte self assembly. A “ring” of high fluorescence intensity advancing with time towards the capsule centre was observed during incubation of capsules with fluorescent-labeled biotin. Fluorescence intensity was build up in capsule areas where binding to avidin occurred and was visualized in real time. A model for the diffusion process in microcapsules was developed and experimental data was plotted and fitted well with trends predicted by the model. The value of the diffusion coefficient for biotin–fluorescein was determined to be 3.5 × 10−8 cm2/s, which is comparable to literature values of similar sized molecules.

  • 42.
    Meng, Lingyin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Mak, Wing Cheung
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Positively-charged hierarchical PEDOT interface with enhanced electrode kinetics for NADH-based biosensors2018In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 120, p. 115-121Article in journal (Refereed)
    Abstract [en]

    Poly(ethylenedioxythiophene) (PEDOT) has attracted considerable attention as an advanced electrode material for electrochemical sensors and biosensors, due to its unique electrical and physicochemical properties. Here, we demonstrate the facile preparation of a positively-charged and hierarchical micro-structured PEDOT electrochemical interface with enhanced electrode kinetics for the electrooxidation of NADH. Processable PEDOT colloidal microparticles (PEDOT CMs) were synthesised by template-assisted polymerisation and were then utilised as building blocks for the fabrication of hierarchically-structured electrodes with a larger accessible electroactive surface (2.8 times larger than that of the benchmark PEDOT:PSS) and inter-particle space, thus improving electrode kinetics. The intrinsic positive charge of the PEDOT CMs further facilitated the detection of negatively-charged molecules by electrostatic accumulation. Due to the synergistic effect, these hierarchically-structured PEDOT CMs electrodes exhibited improved NADH electrooxidation at lower potentials and enhanced electrocatalytic activity compared to the compact structure of conventional PEDOT:PSS electrodes. The PEDOT CMs electrodes detected NADH over the range of 20–240 μM, with a sensitivity of 0.0156 μA/μM and a limit of detection of 5.3 μM. Moreover, the PEDOT CMs electrode exhibited a larger peak separation from the interferent ascorbic acid, and improved stability. This enhanced analytical performance for NADH provides a sound basis for further work coupling to a range of NAD-dependent dehydrogenases for applications in biosensing, bio-fuel cells and biocatalysis.

  • 43.
    Mousavisani, Seyedeh Zeinab
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering. Eletroanalytical Chemistry Research Laboratory, Department of Analytical Chemistry, Faculty of Chemistry, University of Mazandaran, Babolsar, Iran.
    Raoof, Jahan-Bakhsh
    Eletroanalytical Chemistry Research Laboratory, Department of Analytical Chemistry, Faculty of Chemistry, University of Mazandaran, Babolsar, Iran.
    Cheung, Kwan Yee
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Hernandez Camargo, Aura Rocio
    Department of Biomedical Science, Faculty of Health and Society, Malmö University, Malmö, Sweden; Investigación en procesos de transformación de materiales para la industria farmacéutica, Departamento de Farmacia, Universidad Nacional de Colombia, Sede Bogotá, Colombia; Biofilms - Research Center for Biointerfaces, Malmö University, Malmö, Sweden.
    Ruzgas, Tautgirdas
    Department of Biomedical Science, Faculty of Health and Society, Malmö University, Malmö, Sweden; Biofilms - Research Center for Biointerfaces, Malmö University, Malmö, Sweden.
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering. Cranfield Univ, England.
    Mak, Wing Cheung
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Integrating an ex-vivo skin biointerface with electrochemical DNA biosensor for direct measurement of the protective effect of UV blocking agents2019In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 128, p. 159-165Article in journal (Refereed)
    Abstract [en]

    Skin cancer is the most frequent kind of cancer in white people in many parts of the world. UV-induced DNA damage and genetic mutation can subsequently lead to skin cancer. Therefore development of new biosensing strategies for detection of UV-induced DNA damage is of great importance. Here we demonstrate a novel combination of an ex-vivo skin biointerface and an electrochemical DNA sensor for the direct detection of UV-induced DNA damage and investigation the protective effect of various UV blockers (Zinc-oxide (ZnO), titanium dioxide (TiO2) nanoparticles (NPs) and sunscreens) against DNA damage. A diazonium modified screen-printed carbon electrode immobilized with a DNA sequence related to the p53 tumour suppressor gene, the most commonly affected gene in human UV-induced skin cancer, was applied as an electrochemical DNA sensor. Electrochemical impedance spectroscopy (EIS) was employed for the detection of DNA damage induced by UV-A radiation by following the changes in charge transfer resistance (R-ct). The protective effects of UV blockers applied onto a pig skin surface (a suitable model representing human skin) were successfully detected by the DNA sensor. We observed that the naked skin has little UV protection showing an 18.2% decreases in Delta R/R values compared to the control, while applying both NPs and NP-formulated sunscreens could significantly reduce DNA damage, resulting in a decrease in Delta R/R values of 67.1% (ZnO NPs), 77.2% (TiO2 NPs), 77.1% (sunscreen 1) and 92.4% (sunscreen 2), respectively. Moreover, doping moisturising cream with NPs could provide a similar DNA protective effect. This new method is a biologically relevant alternative to animal testing and offers advantages such as fast, easy and inexpensive processing, in addition to its miniaturised dimension, and could be used for a range of applications in other sources of DNA damage and the protective effect of different UV blocking agents and other topical formulations.

  • 44.
    Mousavisani, Seyedeh Zeinab
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering. Eletroanalytical Chemistry Research Laboratory, Department of Analytical Chemistry, Faculty of Chemistry, University of Mazandaran, Babolsar, Iran.
    Raoof, Jahan-Bakhsh
    Eletroanalytical Chemistry Research Laboratory, Department of Analytical Chemistry, Faculty of Chemistry, University of Mazandaran, Babolsar, Iran.
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Ojani, Reza
    Eletroanalytical Chemistry Research Laboratory, Department of Analytical Chemistry, Faculty of Chemistry, University of Mazandaran, Babolsar, Iran.
    Mak, Wing Cheung
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Label-free DNA sensor based on diazonium immobilisation for detection of DNA damage in breast cancer 1 gene2018In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 264, p. 59-66Article in journal (Refereed)
    Abstract [en]

    Electrochemical DNA biosensors offer simple and rapid tools for detection of DNA sequences or damaged genes associated with human disease. The performance of electrochemical DNA sensors is critically dependent on the quality of the DNA immobilisation. Many DNA biosensors have been focused on studying DNA hybridisation preformed under relatively mild assay conditions, while the development of stable DNA biosensors to study DNA damage under a much harsher condition typically in the presence of reactive oxygen species is more challenging. In this article, we developed an electrochemical DNA biosensor based on a stable diazonium-modified screen-printed carbon electrode (SPCE) for the detection of damage in DNA sequences related to the BRCA1 gene by using electrochemical impedance spectroscopy (EIS). The successful preparation of the DNA sensor was confirmed by FTIR-ATR, contact angle and electrochemical measurements. The DNA sensor exhibited good reproducibility and high stability and could also have potential for investigation of the glutathione antioxidant effect. (C) 2018 Elsevier B.V. All rights reserved.

  • 45.
    Nordin, Anis Nurashikin
    et al.
    Int Islamic Univ, Malaysia.
    Zainuddin, Ahmad Anwar
    Int Islamic Univ, Malaysia.
    Ab Rahim, Rosminazuin
    Int Islamic Univ, Malaysia.
    Voiculescu, Ioana
    CUNY City Coll, NY 10052 USA.
    Mak, Wing Cheung
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Screen Printed Electromechanical Micro-Total Analysis System (mu tas) For Sensitive and Rapid Detection of Infectious Diseases2017In: BIOSENSORS 2016, ELSEVIER SCIENCE BV , 2017, Vol. 27, p. 100-101Conference paper (Refereed)
    Abstract [en]

    n/a

  • 46.
    Patzelt, Alexa
    et al.
    Charite, Germany.
    Cheung Mak, Wing
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Jung, Sora
    Charite, Germany.
    Knorr, Fanny
    Charite, Germany.
    Meinke, Martina C.
    Charite, Germany.
    Richter, Heike
    Charite, Germany.
    Ruehl, Eckart
    Free University of Berlin, Germany.
    Cheung, Kitt
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Medicine and Health Sciences.
    Tran, Ngo Bich Nga Nathalie
    Charite, Germany.
    Lademann, Juergen
    Charite, Germany.
    Do nanoparticles have a future in dermal drug delivery?2017In: Journal of Controlled Release, ISSN 0168-3659, E-ISSN 1873-4995, Vol. 246, p. 174-182Article in journal (Refereed)
    Abstract [en]

    More and more investigations confirm that nanoparticles are incapable of overcoming the intact skin barrier in vivo. Do nanoparticles still have a future in dermal drug delivery? Unlike many other topically applied substances, nanoparticles have not been reported to utilize the intercellular penetration pathway and preferentially make use of the follicular penetration pathway. Deep penetration into the follicular ducts has been described for a variety of particles and appears to be strongly influenced by particle size. For targeted drug delivery, smart nanoparticles are required which are able to release their loaded drugs subsequent to internal or external trigger stimuli, and thereby enable the translocation of the active agents into the viable epidermis. In the recent manuscript, three nanoparticles systems are summarized and compared which release their model drugs upon different trigger mechanisms. The BSA hydrogel nanoparticles release their model drug TRITC-dextran by passive diffusion due to a concentration gradient via a porous surface. The protease-triggered controlled release BSA nanoparticles release their model drug if they are applied simultaneously with protease nanoparticles, resulting in an enzymatic degradation of the particles and a release of the model drug FITC. Finally, the IR-triggered controlled release AuNP-doped BSA nanoparticles release their model drug FITC after photoactivation with wIRA. For all three nanoparticle systems, the release of their model drugs could be observed. For the first nanoparticle system, only low follicular penetration depths were found which might by due do an agglomeration effect. For the last two nanoparticle systems, deep follicular penetration and even an uptake by the sebaceous glands were verified. In conclusion, it could be demonstrated that nanoparticles do have a future in dermal drug delivery if smart nanoparticle systems are utilized which are able to release their drug at specific times and locations within the hair follicle. (C) 2016 Elsevier B.V. All rights reserved.

  • 47.
    Rezaei, Babak
    et al.
    Amirkabir Univ Technol, Iran.
    Shoushtari, Ahmad Mousavi
    Amirkabir Univ Technol, Iran.
    Rabiee, Mohammad
    Amirkabir Univ Technol, Iran.
    Uzun, Lokman
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering. Hacettepe Univ, Turkey.
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Mak, Wing Cheung
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Electrochemical performance of nanofibrous highly flexible electrodes enhanced by different structural configurations2018In: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 155, p. 81-90Article in journal (Refereed)
    Abstract [en]

    Due to their unique physicomechanical properties, one dimensional (1D) nanostructured conductive materials offer remarkable potential as a flexible electroactive medium for developing miniaturized electronic devices such as supercapacitors, sensors and actuators. In this work, thin films composed of nanocomposite nanofibers with two different architectures, i.e. whiskered nanofibers (WNFs) and hierarchical-structured nanofibers (H-SNFs), were fabricated and their capability to serve as flexible and bendable electrodes were evaluated. The main difference of these two architectures is how the distributions of the nano-fillers (carboxylated multiwalled carbon nanotubes, CMWCNTs) through the nanofibers, i.e. the isotropic and anisotropic arrangements, lead to WNFs and H-SNFs, respectively. The percolation threshold of conduction for the H-SNFs (composed of 0.5 wt% CMWCNTs) and the WNFs (composed of 5 wt% CMWCNTs) were 0.13 S cm(-1) and 0.07 S cm(-1), respectively. Moreover, according to the electrochemical characterizations, although the WNFs had ten orders of magnitude higher nanotube content, the electroactivity and electron transfer rate of H-SNFs was considerably higher than those of WNFs, so that the cyclic voltammetric peak currents of H-SNFs was approximately 1.6 times higher than that of WNFs. As a proof-of-concept, our results indicate that the structural configuration is a major determinative factor, which can largely dictate the final electrical and electrochemical properties of the nanocomposite nanofibers. The bending durability results showed good electrochemical performance even upon 100 bending cycles with 120 bending angles (retained 93.4% and 83.3% of the initial peak currents for H-SNFs and WNFs, respectively). These two flexible nanocomposite nanofibrous structures could be promising materials for the development of flexible electrodes for biosensing to energy storage applications. (C) 2017 Elsevier Ltd. All rights reserved.

    The full text will be freely available from 2019-12-02 15:53
  • 48.
    Rezaei, Babak
    et al.
    Nanotechnology Institute, Amirkabir University of Technology, Tehran, Iran.
    Shoushtari, Ahmad Mousavi
    Textile Engineering Department, AmirKabir University of Technology, Tehran, Iran.
    Rabiee, Mohammad
    Biomaterials Group, Biomedical Engineering Department, Amirkabir University of Technology, Tehran, Iran.
    Uzun, Lokman
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Turner, Anthony
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Mak, Wing Cheung
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Multifactorial modeling and optimization of solution and electrospinning parameters to generate superfine polystyrene nanofibers2018In: Advances in Polymer Technology, ISSN 0730-6679, E-ISSN 1098-2329, Vol. 37, no 8, p. 2743-2755Article in journal (Refereed)
    Abstract [en]

    This study was conducted to provide a quantitative understanding of the influence of the different solution and electrospinning variables on the morphology and the mean diameter of electrospun polystyrene nanofibers. In this regard, the effect of different solvents and ionic additives on the electrical conductivity, viscosity, and surface tension of the electrospinning solutions and thereby the morphology of nanofibers were examined. The results indicated that the morphology of the fibers is extremely dependent on the solvent’s properties, especially volatility and electrical conductivity, and the ionic characteristics of additives. Finally, to estimate the optimal electrospinning conditions for production of nanofibers with minimum possible diameter, modeling of the process was undertaken using the response surface methodology. Experimentally, nanofibers with the finest diameter of 169 ï¿œ 21 nm were obtained under the optimized conditions, and these could be considered promising candidates for a wide practical range of applications ranging from biosensors to filtration.

  • 49.
    Rezaei, Babak
    et al.
    Nanotechnology Institute, Amirkabir University of Technology, Tehran, Iran.
    Shoushtari, Ahmad Mousavi
    Textile Engineering Department, AmirKabir University of Technology, Tehran, Iran.
    Rabiee, Mohammad
    Biomaterials Group, Biomedical Engineering Department, Amirkabir University of Technology, Tehran, Iran.
    Uzun, Lokman
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Wing Cheung, Mak
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    TURNER, APF
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    An electrochemical immunosensor for cardiac Troponin I using electrospun carboxylated multi-walled carbon nanotube-whiskered nanofibres2018In: Talanta: The International Journal of Pure and Applied Analytical Chemistry, ISSN 0039-9140, E-ISSN 1873-3573, Vol. 182, p. 178-186Article in journal (Refereed)
    Abstract [en]

    A sandwich-type nanostructured immunosensor based on carboxylated multi-walled carbon nanotube (CMWCNT)-embedded whiskered nanofibres (WNFs) was developed for detection of cardiac Troponin I (cTnI). WNFs were directly fabricated on glassy carbon electrodes (GCE) by removing the sacrificial component (polyethylene glycol, PEG) after electrospinning of polystyrene/CMWCNT/PEG nanocomposite nanofibres, and utilised as a transducer layer for enzyme-labeled amperometric immunoassay of cTnI. The whiskered segments of CMWCNTs were activated and utilised to immobilise anti-cTnT antibodies. It was observed that the anchored CMWCNTs within the nanofibres were suitably stabilised with excellent electrochemical repeatability. A sandwich-type immuno-complex was formed between cTnI and horseradish peroxidase-conjugated anti-cTnI (HRP-anti-cTnI). The amperometric responses of the immunosensor were studied using cyclic voltammetry (CV) through an enzymatic reaction between hydrogen peroxide and HRP conjugated to the secondary antibody. The nanostructured immunosensor delivered a wide detection range for cTnI from the clinical borderline for a normal person (0.5-2 ng mL(-1)) to the concentration present in myocardial infarction patients (amp;gt; 20 ng mL(-1)), with a detection limit of similar to 0.04 ng mL(-1). It also showed good reproducibility and repeatability for three different cTnI concentration (1, 10 and 25 ng mL(-1)) with satisfactory relative standard deviations (RSD). Hence, the proposed nanostructured immunosensor shows potential for point-of-care testing.

    The full text will be freely available from 2020-01-31 16:17
  • 50.
    Sankoh, Supannee
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering. Prince Songkla University, Thailand.
    Vagin, Mikhail
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Sekretareva, Alina
    Linköping University, Faculty of Science & Engineering. Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Stanford University, CA 94305 USA.
    Thavarungkul, Panote
    Prince Songkla University, Thailand.
    Kanatharana, Proespichaya
    Prince Songkla University, Thailand.
    Mak, Wing Cheung
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, Faculty of Science & Engineering.
    Colloid electrochemistry of conducting polymer: towards potential-induced in-situ drug release2017In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 228, p. 407-412Article in journal (Refereed)
    Abstract [en]

    Over the past decades, controlled drug delivery system remains as one of the most important area in medicine for various diseases. We have developed a new electrochemically controlled drug release system by combining colloid electrochemistry and electro-responsive microcapsules. The pulsed electrode potential modulation led to the appearance of two processes available for the time-resolved registration in colloid microenvironment: change of the electronic charge of microparticles (from 0.5 ms to 0.1 s) followed by the drug release associated with ionic equilibration (1-10 s). The dynamic electrochemical measurements allow the distinction of drug release associated With ionic relaxation and the change of electronic charge of conducting polymer colloid microparticles. The amount of released drug (methylene blue) could be controlled by modulating the applied potential. Our study demonstrated a surface-potential driven controlled drug release of dispersion of conducting polymer carrier at the electrode interfaces, while the bulk colloids dispersion away from the electrode remains as a reservoir to improve the efficiency of localized drug release. The developed new methodology creates a model platform for the investigations of surface potential-induced in-situ electrochemical drug release mechanism. (C) 2017 Elsevier Ltd. All rights reserved.

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