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  • 1.
    Aili, Daniel
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Selegård, Robert
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Baltzer, Lars
    Division of Organic Chemistry, Department of Biochemistry and Organic Chemistry, BMC, Box 576, Uppsala University, SE-751 23 Uppsala, Sweden.
    Enander, Karin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Liedberg, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Colorimetric Protein Sensing by Controlled Assembly of Gold Nanoparticles Functionalized with Synthetic Receptors2009Inngår i: Small, ISSN 1613-6810, Vol. 5, nr 21, s. 2445-2452Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A strategy for colorimetric sensing of proteins, based on the induced assembly of polypeptide-functionalized gold nanoparticles, is described. Recognition was accomplished using a polypeptide sensor scaffold designed to specifically bind the model analyte, human carbonic anhydrase II (HCAII). The extent of particle aggregation, induced by the Zn2+-triggered dimerization and folding of a second polypeptide also present on the surface of the gold nanoparticle, gave a readily detectable colorimetric shift that was dependent on the concentration of the target protein. In the absence of HCAII, particle aggregation resulted in a major redshift of the plasmon peak whereas analyte binding prevented formation of dense aggregates, significantly reducing the magnitude of the redshift. The limit of detection of HCAII was estimated to be around 15 nM. The versatility of the technique was demonstrated using a second model system based on the recognition of a peptide sequence from the tobacco mosaic virus coat protein (TMVP by a recombinant antibody fragment. This strategy is proposed as a generic platform for robust and specific protein analysis that can be further developed for monitoring a wide range of target proteins.

  • 2.
    Aili, Daniel
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Sensorvetenskap och Molekylfysik. Linköpings universitet, Tekniska högskolan.
    Selegård, Robert
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Baltzer, Lars
    Uppsala University .
    Enander, Karin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Sensorvetenskap och Molekylfysik. Linköpings universitet, Tekniska högskolan.
    Liedberg, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Sensorvetenskap och Molekylfysik. Linköpings universitet, Tekniska högskolan.
    Colorimetric sensing: Small 21/20092009Inngår i: Small, ISSN 1613-6810, E-ISSN 1613-6829, Vol. 5, nr 21Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    The cover picture illustrates a novel concept for colorimetric protein sensing based on the controllable assembly of polypeptide-functionalized gold nanoparticles. Recognition of the analyte is accomplished by polypeptide-based synthetic receptors immobilized on gold nanoparticles. Also present on the particle surface is a de novo-designed helix-loop-helix polypeptide that homodimerizes and folds into four-helix bundles in the presence of Zn2+, resulting in particle aggregation. Analyte binding interferes with the folding-induced aggregation, giving rise to a clearly detectable colorimetric response.

  • 3.
    Aronsson, Christopher
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Selegård, Robert
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten.
    Aili, Daniel
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Zinc-Triggered Hierarchical Self-Assembly of Fibrous Helix-Loop-Helix Peptide Superstructures for Controlled Encapsulation and Release2016Inngår i: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 49, nr 18, s. 6997-7003Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We demonstrate a novel route for hierarchical self-assembly of sub-micrometer-sized peptide superstructures that respond to subtle changes in Zn2+ concentration. The self-assembly process is triggered by a specific folding-dependent coordination of Zn2+ by a de novo designed nonlinear helix-loop-helix peptide, resulting in a propagating fiber formation and formation of spherical superstructures. The superstructures further form larger assemblies that can be completely disassembled upon removal of Zn2+ or degradation of the nonlinear peptide. This flexible and reversible assembly strategy of the superstructures enables facile encapsulation of nanoparticles and drugs that can be released by means of different stimuli.

  • 4.
    Bengtsson, Torbjörn
    et al.
    Örebro University, Sweden.
    Zhang, Boxi
    Karolinska Institutet, Sweden.
    Selegård, Robert
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten. Örebro University, Sweden.
    Wiman, Emanuel
    Örebro University, Sweden.
    Aili, Daniel
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Khalaf, Hazem
    Örebro University, Sweden.
    Dual action of bacteriocin PLNC8 alpha beta through inhibition of Porphyromonas gingivalis infection and promotion of cell proliferation2017Inngår i: Pathogens and Disease, E-ISSN 2049-632X, Vol. 75, nr 5, artikkel-id ftx064Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Periodontitis is a chronic inflammatory disease that is characterised by accumulation of pathogenic bacteria, including Porphyromonas gingivalis, in periodontal pockets. The lack of effective treatments has emphasised in an intense search for alternative methods to prevent bacterial colonisation and disease progression. Bacteriocins are bacterially produced antimicrobial peptides gaining increased consideration as alternatives to traditional antibiotics. We show rapid permeabilisation and aggregation of P. gingivalis by the two-peptide bacteriocin PLNC8 alpha beta. In a cell culture model, P. gingivalis was cytotoxic against gingival fibroblasts. The proteome profile of fibroblasts is severely affected by P. gingivalis, including induction of the ubiquitin-proteasome pathway. PLNC8 alpha beta enhanced the expression of growth factors and promoted cell proliferation, and suppressed proteins associated with apoptosis. PLNC8 alpha beta efficiently counteracted P. gingivalis-mediated cytotoxicity, increased expression of a large number of proteins and restored the levels of inflammatory mediators. In conclusion, we show that bacteriocin PLNC8 alpha beta displays dual effects by acting as a potent antimicrobial agent killing P. gingivalis and as a stimulatory factor promoting cell proliferation. We suggest preventive and therapeutical applications of PLNC8 alpha beta in periodontitis to supplement the host immune defence against P. gingivalis infection and support wound healing processes.

  • 5.
    Borglin, Johan
    et al.
    University of Gothenburg, Sweden.
    Selegård, Robert
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Aili, Daniel
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Ericson, Marica B.
    University of Gothenburg, Sweden.
    Peptide Functionalized Gold Nanoparticles as a Stimuli Responsive Contrast Medium in Multiphoton Microscopy2017Inngår i: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 17, nr 3, s. 2102-2108Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    There is a need for biochemical contrast mediators with high signal-to-noise ratios enabling noninvasive biomedical sensing, for example, for neural sensing and protein protein interactions, in addition to cancer diagnostics. The translational challenge is to develop a biocompatible approach ensuring high biochemical contrast while avoiding a raise of the background signal. We here present a concept where gold nanoparticles (AuNPs) can be utilized as a stimuli responsive contrast medium by chemically triggering their ability to exhibit multiphoton-induced luminescence (MIL) when performing multiphoton laser scanning microscopy (MPM). Proof-of-principle is demonstrated using peptide-functionalized AuNPs sensitive to zinc ions (Zn2+). Dispersed particles are invisible in the MPM until addition of millimolar concentrations of Zn2+ upon which MIL is enabled through particle aggregation caused by specific peptide interactions and folding. The process can be reversed by removal of the Zn2+ using a chelator, thereby resuspending the AuNPs. In addition, the concept was demonstrated by exposing the particles to matrix metalloproteinase-7 (MMP-7) causing peptide digestion resulting in AuNP aggregation, significantly elevating the MIL signal from the background. The approach is based on the principle that aggregation shifts the plasmon resonance, elevating the absorption cross section in the near-infrared wavelength region enabling onset of MIL. This Letter demonstrates how biochemical sensing can be obtained in far-field MPM and should be further exploited as a future tool for noninvasive optical biosensing.

  • 6.
    Chen, Hu
    et al.
    Nanyang Technology University, Singapore; Nanyang Technology University, Singapore; University of Loughborough, England.
    Chen, Peng
    Nanyang Technology University, Singapore; Centre Biomimet Sensor Science, Singapore.
    Huang, Jingfeng
    Nanyang Technology University, Singapore; Nanyang Technology University, Singapore.
    Selegård, Robert
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Platt, Mark
    University of Loughborough, England.
    Palaniappan, Alagappan
    Nanyang Technology University, Singapore; Centre Biomimet Sensor Science, Singapore.
    Aili, Daniel
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Iing Yoong Tok, Alfred
    Nanyang Technology University, Singapore; Nanyang Technology University, Singapore.
    Liedberg, Bo
    Nanyang Technology University, Singapore; Centre Biomimet Sensor Science, Singapore.
    Detection of Matrilysin Activity Using Polypeptide Functionalized Reduced Graphene Oxide Field-Effect Transistor Sensor2016Inngår i: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 88, nr 6, s. 2994-2998Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A novel approach for rapid and sensitive detection of matrilysin (MMP-7, a biomarker involved in the degradation of various macromolecules) based on a polypeptide (JR2EC) functionalized reduced graphene oxide (rGO) field effect transistor (FET) is reported. MMP-7 specifically digests negatively charged JR2EC immobilized on rGO, thereby modulating the conductance of rGO-FET. The proposed assay enabled detection of MMP-7 at clinically relevant concentrations with a limit of detection (LOD) of 10 ng/mL (400 pM), attributed to the significant reduction of the net charge of JR2EC upon digestion by MMP-7. Quantitative detection of MMP-7 in human plasma was further demonstrated with a LOD of 40 ng/mL, illustrating the potential for the proposed methodology for tumor detection and carcinoma diagnostic (e.g., lung cancer and salivary gland cancer). Additionally, excellent specificity of the proposed assay was demonstrated using matrix metallopeptidase 1 (MMP-1), a protease of the same family. With appropriate selection and modification of polypeptides, the proposed assay could be extended for detection of other enzymes with polypeptide digestion capability.

  • 7.
    Chen, Peng
    et al.
    Nanyang Technology University, Singapore.
    Selegård, Robert
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Sensorvetenskap och Molekylfysik. Linköpings universitet, Tekniska högskolan.
    Aili, Daniel
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Sensorvetenskap och Molekylfysik. Linköpings universitet, Tekniska högskolan.
    Liedberg, Bo
    Nanyang Technology University, Singapore.
    Peptide functionalized gold nanoparticles for colorimetric detection of matrilysin (MMP-7) activity2013Inngår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 5, nr 19, s. 8973-8976Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A peptide with two cleavage sites for MMP-7 has been synthesized and immobilized on gold nanoparticles (AuNPs) through a cysteine residue. Digestion of the peptide by MMP-7 decreases its size and net charge, which leads to the aggregation of the AuNPs. The color shift caused by aggregation enables a direct and quantitative measurement of the concentration and activity of MMP-7 with an estimated limit of detection of 5 nM (0.1 μg mL−1).

  • 8.
    Christoffersson, Jonas
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teknisk biologi. Linköpings universitet, Tekniska fakulteten.
    Aronsson, Christopher
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Jury, Michael
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Selegård, Robert
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Aili, Daniel
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Mandenius, Carl-Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teknisk biologi. Linköpings universitet, Tekniska fakulteten.
    Fabrication of modular hyaluronan-PEG hydrogels to support 3D cultures of hepatocytes in a perfused liver-on-a-chip device2018Inngår i: Biofabrication, ISSN 1758-5082, E-ISSN 1758-5090, Vol. 11, nr 1, s. 1-13, artikkel-id 015013Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Liver cell culture models are attractive in both tissue engineering and for development of assays for drug toxicology research. To retain liver specific cell functions, the use of adequate cell types and culture conditions, such as a 3D orientation of the cells and a proper supply of nutrients and oxygen, are critical. In this article, we show how extracellular matrix mimetic hydrogels can support hepatocyte viability and functionality in a perfused liver-on-a-chip device. A modular hydrogel system based on hyaluronan and poly(ethylene glycol) (HA-PEG), modified with cyclooctyne moieties for bioorthogonal strain-promoted alkyne-azide 1, 3-dipolar cycloaddition (SPAAC), was developed, characterized, and compared for cell compatibility to hydrogels based on agarose and alginate. Hepatoma cells (HepG2) formed spheroids with viable cells in all hydrogels with the highest expression of albumin and urea in alginate hydrogels. By including an excess of cyclooctyne in the HA backbone, azide-modified cell adhesion motifs (linear and cyclic RGD peptides) could be introduced in order to enhance viability and functionality of human induced pluripotent stem cell derived hepatocytes (hiPS-HEPs). In the HA-PEG hydrogels modified with cyclic RGD peptides hiPS-HEPs migrated and grew in 3D and showed an increased viability and higher albumin production compared to when cultured in the other hydrogels. This flexible SPAAC crosslinked hydrogel system enabled fabrication of perfused 3D cell culture of hiPS-HEPs and is a promising material for further development and optimization of liver-on-a-chip devices.

  • 9.
    Christoffersson, Jonas
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teknisk biologi. Linköpings universitet, Tekniska fakulteten.
    Aronsson, Christopher
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Jury, Michael
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Selegård, Robert
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Aili, Daniel
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Mandenius, Carl-Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teknisk biologi. Linköpings universitet, Tekniska fakulteten.
    Fabrication of modular hyaluronan-PEG hydrogels to support 3D cultures of hepatocytes in a perfused liver-on-a-chip device2019Inngår i: Biofabrication, ISSN 1758-5082, E-ISSN 1758-5090, Vol. 11, nr 1, artikkel-id 015013Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Liver cell culture models are attractive in both tissue engineering and for development of assays for drug toxicology research. To retain liver specific cell functions, the use of adequate cell types and culture conditions, such as a 3Dorientation of the cells and a proper supply of nutrients and oxygen, are critical. In this article, we show how extracellular matrix mimetic hydrogels can support hepatocyte viability and functionality in a perfused liver-on-a-chip device. A modular hydrogel system based on hyaluronan and poly(ethylene glycol) (HA-PEG), modified with cyclooctyne moieties for bioorthogonal strain-promoted alkyne-azide 1, 3-dipolar cycloaddition (SPAAC), was developed, characterized, and compared for cell compatibility to hydrogels based on agarose and alginate. Hepatoma cells (HepG2) formed spheroids with viable cells in all hydrogels with the highest expression of albumin and urea in alginate hydrogels. By including an excess of cyclooctyne in theHA backbone, azide-modified cell adhesion motifs (linear and cyclicRGDpeptides) could be introduced in order to enhance viability and functionality of human induced pluripotent stem cell derived hepatocytes (hiPS-HEPs). In the HA-PEG hydrogels modified with cyclicRGDpeptides hiPS-HEPs migrated and grew in 3D and showed an increased viability and higher albumin production compared to when cultured in the other hydrogels. This flexible SPAAC crosslinked hydrogel system enabled fabrication of perfused 3D cell culture of hiPS-HEPs and is a promising material for further development and optimization of liver-on-a-chip devices.

  • 10.
    Koon Lim, Seng
    et al.
    Nanyang Technology University, Singapore.
    Sandén, Camilla
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Selegård, Robert
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Liedberg, Bo
    Nanyang Technology University, Singapore.
    Aili, Daniel
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Tuning Liposome Membrane Permeability by Competitive Peptide Dimerization and Partitioning-Folding Interactions Regulated by Proteolytic Activity2016Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, nr 21123, s. 1-9Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Membrane active peptides are of large interest for development of drug delivery vehicles and therapeutics for treatment of multiple drug resistant infections. Lack of specificity can be detrimental and finding routes to tune specificity and activity of membrane active peptides is vital for improving their therapeutic efficacy and minimize harmful side effects. We describe a de novo designed membrane active peptide that partition into lipid membranes only when specifically and covalently anchored to the membrane, resulting in pore-formation. Dimerization with a complementary peptide efficiently inhibits formation of pores. The effect can be regulated by proteolytic digestion of the inhibitory peptide by the matrix metalloproteinase MMP-7, an enzyme upregulated in many malignant tumors. This system thus provides a precise and specific route for tuning the permeability of lipid membranes and a novel strategy for development of recognition based membrane active peptides and indirect enzymatically controlled release of liposomal cargo.

  • 11.
    Mak, Wing Cheung
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biosensorer och bioelektronik. Linköpings universitet, Tekniska högskolan.
    Selegård, Robert
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska högskolan.
    Garbrecht, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Aili, Daniel
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska högskolan.
    Probing Zinc-Protein-Chelant Interactions using Gold Nanoparticles Functionalized with Zinc-Responsive Polypeptides2014Inngår i: Particle & particle systems characterization, ISSN 0934-0866, E-ISSN 1521-4117, Vol. 31, nr 11, s. 1127-1133Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 12.
    Rouhbakhsh, Zeinab
    et al.
    Not Found:Linkoping Univ, Dept Phys Chem and Biol, Div Mol Phys, Lab Mol Mat, S-58183 Linkoping, Sweden; Linkoping Univ, Dept Phys, Div Chem, Chem and Biol, S-58183 Linkoping, Sweden.
    Aili, Daniel
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Martinsson, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Svärd, Anna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Back, Marcus
    Ferdowsi Univ Mashhad, Iran.
    Housaindokht, Mohammad R.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten.
    Nilsson, Peter
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemi. Linköpings universitet, Tekniska fakulteten. Ferdowsi Univ Mashhad, Iran.
    Selegård, Robert
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Self-Assembly of a Structurally Defined Chiro-Optical Peptide-Oligothiophene Hybrid Material2018Inngår i: ACS OMEGA, ISSN 2470-1343, Vol. 3, nr 11, s. 15066-15075Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Conducting polymers are routinely used in optoelectronic biomaterials, but large polymer polydispersity and poor aqueous compatibility complicate integration with biomolecular templates and development of discrete and defined supramolecular complexes. Herein, we report on a chiro-optical hybrid material generated by the self-assembly of an anionic peptide and a chemically defined cationic pentameric thiophene in aqueous environment. The peptide acts as a stereochemical template for the thiophene and adopts an a-helical conformation upon association, inducing optical activity in the thiophene r-n * transition region. Theoretical calculations confirm the experimentally observed induced structural changes and indicate the importance of electrostatic interactions in the complex. The association process is also probed at the substrate-solvent interface using peptide-functionalized gold nanoparticles, indicating that the peptide can also act as a scaffold when immobilized, resulting in structurally well-defined supramolecular complexes. The hybrid complex could rapidly be assembled, and the kinetics of the formation could be monitored by utilizing the local surface plasmon resonance originating from the gold nanoparticles. We foresee that these findings will aid in designing novel hybrid materials and provide a possible route for the development of functional optoelectronic interfaces for both biomaterials and energy harvesting applications.

  • 13.
    Selegård, Robert
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Aronsson, Christopher
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Brommesson, Caroline
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär ytfysik och nanovetenskap. Linköpings universitet, Tekniska fakulteten.
    Dånmark, Staffan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Aili, Daniel
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Folding driven self-assembly of a stimuli-responsive peptide-hyaluronan hybrid hydrogel2017Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, artikkel-id 7013Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Protein-metal ion interactions are ubiquitous in nature and can be utilized for controlling the self-assembly of complex supramolecular architectures and materials. Here, a tunable supramolecular hydrogel is described, obtained by self-assembly of a Zn2+-responsive peptide-hyaluronic acid hybrid synthesized using strain promoted click chemistry. Addition of Zn2+ triggers folding of the peptides into a helix-loop-helix motif and dimerization into four-helix bundles, resulting in hydrogelation. Removal of the Zn2+ by chelators results in rapid hydrogel disassembly. Degradation of the hydrogels can also be time-programed by encapsulation of a hydrolyzing enzyme within the gel, offering multiple possibilities for modulating materials properties and release of encapsulated species. The hydrogel further shows potential antioxidant properties when evaluated using an in vitro model for reactive oxygen species.

  • 14.
    Selegård, Robert
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska högskolan.
    Enander, Karin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska högskolan.
    Aili, Daniel
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska högskolan.
    Generic Phosphatase Activity Detection using Zinc Mediated Aggregation Modulation of Polypeptide-Modified Gold Nanoparticles2014Inngår i: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 6, nr 23, s. 14204-14212Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A challenge in the design of plasmonic nanoparticle-based colorimetric assays is that the change in colloidal stability, which generates the colorimetric response, is often directly linked to the biomolecular recognition event. New assay strategies are hence required for every type of substrate and enzyme of interest. Here, a generic strategy for monitoring of phosphatase activity is presented where substrate recognition is completely decoupled from the nanoparticle stability modulation mechanism, which enables detection of a wide range of enzymes using different natural substrates with a single simple detection scheme. Phosphatase activity generates inorganic phosphate that forms an insoluble complex with Zn2+. In a sample containing a preset concentration of Zn2+, phosphatase activity will markedly reduce the concentration of dissolved Zn2+ from the original value, which in turn affects the aggregation of gold nanoparticles functionalized with a designed Zn2+ responsive polypeptide. The change in nanoparticle stability thus provides a rapid and sensitive readout of the phosphatase activity. The assay is not limited to a particular enzyme or enzyme substrate, which is demonstrated using three completely different phosphatases and five different substrates, and thus constitutes a highly interesting system for drug screening and diagnostics.

  • 15.
    Selegård, Robert
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Rouhbalchsh, Zeinab
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Shirani, Hamid
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemi. Linköpings universitet, Tekniska fakulteten.
    Johansson, Leif
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten.
    Norman, Patrick
    KTH Royal Institute Technology, Sweden.
    Linares, Mathieu
    KTH Royal Institute Technology, Sweden.
    Aili, Daniel
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Nilsson, Peter
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemi. Linköpings universitet, Tekniska fakulteten.
    Distinct Electrostatic Interactions Govern the Chiro-Optical Properties and Architectural Arrangement of Peptide-Oligothiophene Hybrid Materials2017Inngår i: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 50, nr 18, s. 7102-7110Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The development of chiral optoelectronic materials is of great interest due to their potential of being utilized in electronic devices, biosensors, and artificial enzymes. Herein, we report the chiral optical properties and architectural arrangement of optoelectronic materials generated from noncovalent self-assembly of a cationic synthetic peptide and five chemically defined anionic pentameric oligothiophenes. The peptide-oligothiophene hybrid materials exhibit a three-dimensional ordered helical structure and optical activity in the pi-pi* transition region that are observed due to a single chain induced chirality of the conjugated thiophene backbone upon interaction with the peptide. The latter property is highly dependent on electrostatic interactions between the peptide and the oligothiophene, verifying that a distinct spacing of the carboxyl groups along the thiophene backbone is a major chemical determinant for having a hybrid material with distinct optoelectronic properties. The necessity of the electrostatic interaction between specific carboxyl functionalities along the thiophene backbone and the lysine residues of the peptide, as well as the induced circular dichroism of the thiophene backbone, was also confirmed by theoretical calculations. We foresee that our findings will aid in designing optoelectronic materials with dynamic architectonical precisions as well as offer the possibility to create the next generation of materials for organic electronics and organic bioelectronics.

  • 16.
    Skyttner, Camilla
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Selegård, Robert
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Larsson, Jakob
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Aronsson, Christopher
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Enander, Karin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Aili, Daniel
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär fysik. Linköpings universitet, Tekniska fakulteten.
    Sequence and length optimization of membrane active coiled coils for triggered liposome release2019Inngår i: Biochimica et Biophysica Acta - Biomembranes, ISSN 0005-2736, E-ISSN 1879-2642, Vol. 1862, nr 2, s. 449-456Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Defined and tunable peptide-lipid membrane interactions that trigger the release of liposome encapsulated drugs may offer a route to improving the efficiency and specificity of liposome-based drug delivery systems, but this require means to tailor the performance of the membrane active peptides. In this paper, the membrane activity of a de novo designed coiled coil peptide has been optimized with respect to sequence and size to improve release efficiency of liposome encapsulated cargo. The peptides were only membrane active when covalently conjugated to the liposomes. Two amino acid substitutions were made to enhance the amphipathic characteristics of the peptide, which increased the release by a factor of five at 1 mu M. Moreover, the effect of peptide length was investigated by varying the number of heptad repeats from 2 to 5, yielding the peptides KVC2-KVC5. The shortest peptide (KVC2) showed the least interaction with the membrane and proved less efficient than the longer peptides in releasing the liposomal cargo. The peptide with three heptads (KVC3) caused liposome aggregation whereas KVC4 proved to effectively release the liposomal cargo without causing aggregation. The longest peptide (KVC5) demonstrated the most defined a-helical secondary structure and the highest liposome surface concentration but showed slower release kinetics than KVC4. The four heptad peptide KVC4 consequently displayed optimal properties for triggering the release and is an interesting candidate for further development of bioresponsive and tunable liposomal drug delivery systems.

  • 17.
    Wang, Yusong
    et al.
    Nanyang Technology University, Singapore Nanyang Technology University, Singapore .
    Aili, Daniel
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Sensorvetenskap och Molekylfysik. Linköpings universitet, Tekniska högskolan.
    Selegård, Robert
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Sensorvetenskap och Molekylfysik. Linköpings universitet, Tekniska högskolan.
    Tay, Yeeyan
    Nanyang Technology University, Singapore .
    Baltzer, Lars
    Uppsala University, Sweden .
    Zhang, Hua
    Nanyang Technology University, Singapore Nanyang Technology University, Singapore .
    Liedberg, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Sensorvetenskap och Molekylfysik. Linköpings universitet, Tekniska högskolan.
    Specific functionalization of CTAB stabilized anisotropic gold nanoparticles with polypeptides for folding-mediated self-assembly2012Inngår i: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 22, nr 38, s. 20368-20373Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Anisotropic nanoparticles stabilized by cetyltrimethylammonium bromide (CTAB) are notoriously difficult to homogenously functionalize using conventional gold-thiol chemistry. Using surface assisted laser desorption time of flight mass spectroscopy and scanning transmission electron microscopy-energy dispersive X-ray spectroscopy, we demonstrate that silver species adsorbed on the particle surface prevent effective surface functionalization. When covered by a thin gold film, particle functionalization was drastically improved. A thiol-containing polypeptide was immobilized on arrowhead gold nanorods (NRs) and was subsequently able to selectively heteroassociate with a complementary polypeptide resulting in a folding-mediated bridging aggregation of the NRs. Despite using arrowhead NRs with a pronounced difference in surface arrangement on the {111} facets on the arrowheads compared to the {100} facets at the particle sides, the polypeptides were efficiently and homogeneously immobilized on the particles after gold film overgrowth.

  • 18.
    Zeng, Shuangshuang
    et al.
    Uppsala Univ, Sweden.
    Li, Shiyu
    Uppsala Univ, Sweden.
    Utterström, Johanna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biofysik och bioteknik. Linköpings universitet, Tekniska fakulteten.
    Wen, Chenyu
    Uppsala Univ, Sweden.
    Selegård, Robert
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biofysik och bioteknik. Linköpings universitet, Tekniska fakulteten.
    Zhang, Shi-Li
    Uppsala Univ, Sweden.
    Aili, Daniel
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biofysik och bioteknik. Linköpings universitet, Tekniska fakulteten.
    Zhang, Zhen
    Uppsala Univ, Sweden.
    Mechanism and Kinetics of Lipid Bilayer Formation in Solid-State Nanopores2020Inngår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 36, nr 6, s. 1446-1453Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Solid-state nanopores provide a highly versatile platform for rapid electrical detection and analysis of single molecules. Lipid bilayer coating of the nanopores can reduce nonspecific analyte adsorption to the nanopore sidewalls and increase the sensing selectivity by providing possibilities for tethering specific ligands in a cell-membrane mimicking environment. However, the mechanism and kinetics of lipid bilayer formation from vesicles remain unclear in the presence of nanopores. In this work, we used a silicon-based, truncated pyramidal nanopore array as the support for lipid bilayer formation. Lipid bilayer formation in the nanopores was monitored in real time by the change in ionic current through the nanopores. Statistical analysis revealed that a lipid bilayer is formed from the instantaneous rupture of individual vesicle upon adsorption in the nanopores, differing from the generally agreed mechanism that lipid bilayer forms at a high vesicle surface coverage on a planar support. The dependence of the lipid bilayer formation process on the applied bias, vesicle size, and concentration was systematically studied. In addition, the nonfouling properties of the lipid bilayer coated nanopores were demonstrated during long single-stranded DNA translocation through the nanopore array. The findings indicate that the lipid bilayer formation process can be modulated by introducing nanocavities intentionally on the planar surface to create active sites or changing the vesicle size and concentration.

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