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Uzun, Lokman
Publications (6 of 6) Show all publications
Rezaei, B., Shoushtari, A. M., Rabiee, M., Uzun, L., Wing Cheung, M. & TURNER, A. (2018). An electrochemical immunosensor for cardiac Troponin I using electrospun carboxylated multi-walled carbon nanotube-whiskered nanofibres. Talanta: The International Journal of Pure and Applied Analytical Chemistry, 182, 178-186
Open this publication in new window or tab >>An electrochemical immunosensor for cardiac Troponin I using electrospun carboxylated multi-walled carbon nanotube-whiskered nanofibres
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2018 (English)In: 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) Published
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.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Immunosensor; Cardiac Troponin I; Carbon nanotubes; Electrospinning; Whiskered nanofibres
National Category
Analytical Chemistry
Identifiers
urn:nbn:se:liu:diva-147365 (URN)10.1016/j.talanta.2018.01.046 (DOI)000428229200021 ()29501138 (PubMedID)2-s2.0-85042645620 (Scopus ID)
Note

Funding Agencies|Ministry of Science, Research and Technology of Iran; European Commission [PIEF-GA-2013.629251]

Available from: 2018-05-18 Created: 2018-05-18 Last updated: 2018-06-28Bibliographically approved
Rezaei, B., Shoushtari, A. M., Rabiee, M., Uzun, L., Turner, A. & Mak, W. C. (2018). Multifactorial modeling and optimization of solution and electrospinning parameters to generate superfine polystyrene nanofibers. Advances in Polymer Technology, 37(8), 2743-2755
Open this publication in new window or tab >>Multifactorial modeling and optimization of solution and electrospinning parameters to generate superfine polystyrene nanofibers
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2018 (English)In: Advances in Polymer Technology, ISSN 0730-6679, E-ISSN 1098-2329, Vol. 37, no 8, p. 2743-2755Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
John Wiley & Sons, 2018
Keywords
electrospinning process, fibers, ionic additives, modeling, polystyrene
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-151893 (URN)10.1002/adv.21947 (DOI)000457486100004 ()2-s2.0-85041921459 (Scopus ID)
Note

Funding agencies: Ministry of Science, Research and Technology of Iran

Available from: 2018-10-09 Created: 2018-10-09 Last updated: 2019-03-08Bibliographically approved
Osikoya, A., Parlak, O., Murugan, N. .. r., Dikio, E. D., Moloto, H., Uzun, L., . . . Tiwari, A. (2017). Acetylene-sourced CVD-synthesised catalytically active graphene for electrochemical biosensing.. Biosensors & bioelectronics, 89, 496-504
Open this publication in new window or tab >>Acetylene-sourced CVD-synthesised catalytically active graphene for electrochemical biosensing.
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2017 (English)In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 89, p. 496-504Article in journal (Refereed) Published
Abstract [en]

In this study, we have demonstrated the use of a graphene sheet as a fundamental building block to obtain a highly ordered graphene-enzyme electrode for electrochemical biosensing. Firstly, thin graphene sheets were deposited on 1.00 mm thick copper sheet at 850 oC, via chemical vapour deposition (CVD), using acetylene (C2H2) as carbon source in an argon (Ar) and nitrogen (N2) atmosphere. An anionic surfactant was used to introduce electrostatic charges and increase wettability and hydrophilicity on the basal plane of the otherwise hydrophobic graphene, thereby facilitating the assembly of biomolecules on the graphene surface. The bioelectrocatalytic activity of the system was investigated by the assembly of glucose oxidase (GOx) on the surface of the graphene sheet by intermolecular attractive forces. The electrochemical sensing activity of the graphene-based system was explored as a model for bioelectrocatalysis. The bioelectrode exhibited a linear response to glucose concentration from 0.2 to 9.8 mM, with sensitivity of 0.087 µA/µM/cm2 and a detection limit of 0.12 µM (S/N=3). This work sets the stage for the use of acetylene-sourced graphene sheets as fundamental building blocks in the fabrication of electrochemical biosensors and other biocatalytic devices.

Place, publisher, year, edition, pages
Elsevier, 2017
Keywords
CVD-graphene, bioelectronics, theoretical calculation, surfactant modification, 2D-materials
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-128195 (URN)10.1016/j.bios.2016.03.063 (DOI)000391077000048 ()27157880 (PubMedID)
Note

Funding agencies: Swedish Research Council, Sweden [VR-2011-6058357]; Research Directorate of the Vaal University of Technology, South Africa

Available from: 2016-05-20 Created: 2016-05-20 Last updated: 2017-11-30
Uzun, L. & Turner, A. (2016). Molecularly-imprinted polymer sensors: realising their potential. Biosensors & bioelectronics, 76, 131-144
Open this publication in new window or tab >>Molecularly-imprinted polymer sensors: realising their potential
2016 (English)In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 76, p. 131-144Article in journal (Refereed) Published
Abstract [en]

In parallel with recent developments in communications, nanotechnology and materials sciences, there has been extraordinary growth in the area of biosensors, with almost half of the total number of papers ever published (1962-2015) appearing in the last five-years (2010-2015). Molecular imprinting offers a route to the creation of specific and selective cavities in a 3D-polymeric network, which are complementary not only to the size and shape of a target species, but also provide interaction points and a coordination sphere around the template molecule. Given the challenges facing biosensor technologists, it is natural that this approach to create potentially highly stable synthetic ligands as an alternative to, or to compliment natural receptors, should emerge as a key line of interdisciplinary research. Despite the profuse amount of recent literature on molecularly-imprinted polymers (MIPs) and some limited commercial activity, these promising materials still need to overcome some limitations before taking their place in analytical market. In this review, we have focused on the most promising advances in MIP-based biosensors to illustrate how close to market they really are. We present our material under five main sections covering computational design, polymerisation strategies, material combinations, recent sensor designs and manufacturing issues. Each section provides technical details and evaluates the effect on sensor performance. (C) 2015 Elsevier B.V. All rights reserved.

Place, publisher, year, edition, pages
ELSEVIER ADVANCED TECHNOLOGY, 2016
Keywords
MIP biosensors; Computational polymer design; Polymerisation conditions; Monomer combinations; Synthetic receptors; Manufacturing MIPs
National Category
Biological Sciences
Identifiers
urn:nbn:se:liu:diva-123324 (URN)10.1016/j.bios.2015.07.013 (DOI)000364895000012 ()26189406 (PubMedID)
Note

Funding Agencies|European Commission [629251]

Available from: 2015-12-14 Created: 2015-12-11 Last updated: 2017-12-01
Özgür, E., Parlak, O., Uzun, L., Beni, V. & Turner, A. (2015). Porous functional nanofilms for designing bioinspired sensor surfaces. In: Ashutosh Tiwari (Ed.), Proceeding of Advanced Materials World Congress: . Paper presented at Advanced Materials World Congress, Stockholm, Sweden, 22-16 August 2015. Linköping, Sweden: VBRI Press
Open this publication in new window or tab >>Porous functional nanofilms for designing bioinspired sensor surfaces
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2015 (English)In: Proceeding of Advanced Materials World Congress / [ed] Ashutosh Tiwari, Linköping, Sweden: VBRI Press , 2015Conference paper, Oral presentation with published abstract (Other academic)
Abstract [en]

Bio-mimicking of recognition features typical of biological molecules such as aminoacids, peptides, nucleic acid etc. is leading to the design and development of novel functional (artificial) materials for chemical/biochemical sensing applications. The insertion of biological molecules or their active sites into the backbone of synthetic polymers is one of the possible ways to achieve this. Herein, we synthesised a polymerisable derivative of an amino acid (L-histidine) through a set of reactions with 1-(1Hbenzo[d][1,2,3]triazol-1-yl)-2-methylprop-2-en-1-one (MA-Bt), since amino acid residues are the origin for the functional properties and highly selective substrate-binding ability of many extended biological structures. We obtained a functional monomer methacryloylamidohistidine (MAH), which was polymerised with 2-hydroxyethyl methacrylate in presence of polyvinyl alcohol (PVA) on a gold surface. The aim of using PVA was to obtain highly porous polymeric structure. For control purpose, polymers without MAH and PVA were also synthesised. The morphology of the polymeric film on gold surface was characterized with scanning electron microscopy (SEM) and atomic force microscopy (AFM). The obtained polymer showed significant affinity for Cu2+. The electrochemical behaviour of the polymeric films was systematically investigated with differential pulse voltammetry (DPV). The presence of pores was shown to significantly improve the recognition performance of the film.

Place, publisher, year, edition, pages
Linköping, Sweden: VBRI Press, 2015
Keywords
Bio - mimicking ; amino aci ds; porous polymeric film
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:liu:diva-123692 (URN)10.5185/amwc.2015 (DOI)9789188252005 (ISBN)
Conference
Advanced Materials World Congress, Stockholm, Sweden, 22-16 August 2015
Available from: 2016-01-08 Created: 2016-01-08 Last updated: 2016-01-15Bibliographically approved
Golabi, M., Beni, V., Kuralay, F., Uzun, L., Jager, E. & Turner, A. (2015). Use of Phenylboronic Acid Derivatives in Molecular Imprinting of Whole Bacterial Cells. In: 2nd International Congress on Biosensors – BiosensorTR2015, 10-12 June 2015, Izmir, Turkey.: . Paper presented at 2nd International Congress on Biosensors – BiosensorTR2015, 10-12 June 2015, Izmir, Turkey..
Open this publication in new window or tab >>Use of Phenylboronic Acid Derivatives in Molecular Imprinting of Whole Bacterial Cells
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2015 (English)In: 2nd International Congress on Biosensors – BiosensorTR2015, 10-12 June 2015, Izmir, Turkey., 2015Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

The development of novel, rapid and inexpensive methods for the detection of bacteria will be beneficial in many fields including food and water safety, biosecurity, bioprocess control and clinical diagnostics. Of the possible alternatives, biosensors offer great potential to replace or complement traditional culture-based detection methods, which are time consuming, expensive and need equipped laboratories and trained staff.

 

Molecularly-imprinted polymers (MIPs) are bio-inspired artificial receptors that are finding increasing use in biosensors. Unlike bio-receptors, they are more stable, inexpensive and easy to produce. Although imprinting of chemical and biological molecules has been very well studied, there is limited work on the imprinting of whole bacterial cells.  

Bacterial cells are well-known to present several sugar compounds on their outer surface. In this paper, we explore the reversible interaction between boronic groups and diols for the development of highly specific MIPs for intact bacterial cells. 3-aminophenylboronic acid-based MIPs, for the detection of Staphylococcus epidermidis, were fabricated via chronoamperometric methods and   SEM images were used to verify the successful capturing and releasing of the whole bacterial cells. Successful capture and easy release of the bacterial cells, via a competitive approach, was demonstrated. Furthermore, the usefulness of this imprinting process for the specific detection of Staphylococcus epidermidis versus non-target bacteria, Staphylococcus aureus and Streptococcus pneumoniae, was also demonstrated by the use of impedance spectroscopy measurements of bacterial binding to MIPs and NIPs (non-imprinted polymers) electrodes.

National Category
Water Engineering
Identifiers
urn:nbn:se:liu:diva-118106 (URN)
Conference
2nd International Congress on Biosensors – BiosensorTR2015, 10-12 June 2015, Izmir, Turkey.
Available from: 2015-05-21 Created: 2015-05-21 Last updated: 2015-05-29
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