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Öğe Bioapplications of Polythiophene-g-Polyphenylalanine-Covered Surfaces(Wiley-VCH Verlag, 2015) Guler E.; Akbulut H.; Bozokalfa G.; Demir B.; Eyrilmez G.O.; Yavuz M.; Demirkol D.O.; Coskunol H.; Endo T.; Yamada S.; Timur S.; Yagci Y.The fabrication of electro and bioactive surfaces by electrochemical deposition of the thiophene-functionalized polyphenylalanine macromonomer (T-g-PPhe) is reported. The resulting conducting graft copolymer, polythiophene-graft-polyphenylalanine (PT-g-PPhe) formed on the indium tin oxide (ITO) glass surface, is characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and fluorescence microscopy. Then, possible uses of PT-g-PPhe as matrices in the sensor design for both electrochemical biosensing and cell adhesion studies are investigated. In the first part, PT-g-PPhe that is deposited on ITO is further functionalized with the arginylglycylaspartic acid peptide via 1-Ethyl-3-(3 dimethylaminopropyl) carbodiimide for the selective cell adhesion. Immunofluorescence staining is performed to detect the difference between adherences of "integrin ?vß3" receptor positive (U87-MG) and negative (HaCaT) cell lines on to the biofunctional surface. In the second part, an electrochemical glucose sensor is constructed by immobilizing glucose oxidase on the surface of PT-g-PPhe, which is deposited on a glassy carbon electrode. Thiophene-functionalized polyphenylalanine macromonomer is synthesized and used as polymerized form "Polythiophene-graft-polyphenylalanine" in electrochemical biosensing and cell adhesion applications. Initially, it is conducted to glucose sensing via glucose oxidase immobilization, and secondly the constructed surfaces on indium tin oxide within the modification of RGD peptide are used for the selective cell binding in the way of cell viability and electrochemical biosensing platform. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.Öğe Catechol-Attached Polypeptide with Functional Groups as Electrochemical Sensing Platform for Synthetic Cannabinoids(American Chemical Society, 2020) Durmus C.; Aydindogan E.; Gumus Z.P.; Endo T.; Yamada S.; Coskunol H.; Timur S.Herein, we first constructed a functional surface using a catechol-attached polypeptide (CtP) for the detection of JWH-018 (N-4-hydroxypentyl metabolite). K2 antibody was then incorporated to the polymer via covalent cross-linker. Step-by-step modifications on the glassy carbon electrode surface were characterized by electrochemical measurements such as differential pulse voltammetry, cyclic voltammetry, impedance spectroscopy, and X-ray photoelectron spectroscopy. Linearity and the limit of detection for JWH-018 (N-4-hydroxypentyl metabolite) were determined as 10-500 ng/mL with an equation of y = 0.0018x + 0.136 (R2 = 0.993) and 5.892 ng/mL, respectively. The selectivity of the biosensor was evaluated with different interfering molecules (methamphetamine, codeine, and cocaine). Finally, the biosensor was successfully used in the determination of JWH-018 (N-4-hydroxypentyl metabolite) in spiked synthetic urine samples, and a high-performance liquid chromatography (HPLC) system was used as a reference method to confirm the sample application. The results show that this biosensor platform can be applied to detect other JWH series of synthetic cannabinoids with high sensitivity and accuracy. Copyright © 2019 American Chemical Society.Öğe An immunoelectrochemical platform for the biosensing of ‘Cocaine use’(Elsevier B.V., 2017) Yilmaz Sengel T.; Guler E.; Gumus Z.P.; Aldemir E.; Coskunol H.; Akbulut H.; Goen Colak D.; Cianga I.; Yamada S.; Timur S.; Endo T.; Yagci Y.In the present work, we demonstrate a novel surface design by combination of benzoylecgonine (BE) antibody and poly-L-phenylalanine bearing electroactive macromonomer (EDOT-BTDA-PPhe). This system served as an electro-immunosensor platform for the analysis of cocaine use by detecting both BE and cocaine. To construct the immunosensor, a glassy carbon electrode was covered with EDOT-BTDA-PPhe. Subsequently, BE antibody was immobilized on the polypeptide chains. The surface modifications were confirmed by electrochemical techniques. The immunosensor was used for the electrochemical detection of BE and cocaine as evidence of drug addiction. For both analytes, linearity was obtained between 0.5–25 µM. Finally, the proposed system was successfully employed for the analysis of synthetic biological fluids. © 2017 Elsevier B.V.Öğe Polypeptide with electroactive endgroups as sensing platform for the abused drug ‘methamphetamine’ by bioelectrochemical method(Elsevier B.V., 2016) Demir B.; Yilmaz T.; Guler E.; Gumus Z.P.; Akbulut H.; Aldemir E.; Coskunol H.; Colak D.G.; Cianga I.; Yamada S.; Timur S.; Endo T.; Yagci Y.Affinity-type sensors have emerged as outstanding platforms in the detection of diagnostic protein markers, nucleic acids and drugs. Thus, these novel platforms containing antibodies could be integrated into the monitoring systems for abused drugs. Herein, we established a novel detection platform for the analysis of a common illicit drug; methamphetamine (METH). Initially, a fluorescent-labeled polypeptide (EDOT-BTDA-Pala), derived from L-alanine N-carboxyanhydride (L-Ala-NCA) via ring-opening polymerization using 4,7-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)benzo[c][1,2,5]thiadiazole-5,6-diamine (EDOT-NH2-BTDA) as initiator, was employed as a glassy carbon electrode (GCE) covering host, in order to immobilize the METH-selective antibody. Prior to the examination of analytical features, GCE/EDOT-BTDA-Pala/Antibody surface was successfully characterized in the way of electrochemical (cyclic voltammetry and electrochemical impedance spectroscopy) and microscopic techniques (scanning electron microscopy and fluorescence microscopy). As for the analytical characterization, linearity and limit of detection (LOD) were found as 10–100 µg/mL with an equation of y=0.0429x-0.2347, (R2=0.996) and 13.07 µg/mL, respectively. Moreover, sample application using artificial urine, saliva and serum samples spiked with METH (10, 25, 50 µg/mL) were performed and LC-MS/MS system was used for further confirmation. The described platform can be adapted to monitor the other types of abused drugs by using suitably selected biorecognition elements. © 2016 Elsevier B.V.
