Yazar "Abaci, Serdar" seçeneğine göre listele

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    Characterization of poly(vinylferrocenium) coated surfaces and their applications in DNA sensor technology
    (Springer, 2010) Kuralay, Filiz; Erdem, Arzum; Abaci, Serdar; Ozyoruk, Haluk; Yildiz, Attila
    Poly(vinylferrocenium) (PVF+) modified gold (Au) electrode was developed in this study for the electrochemical sensing of deoxyribonucleic acid (DNA) hybridization based on the oxidation signals of polymer and guanine, and also for the electrochemical investigation of interaction of anticancer drug, mitomycin C (MC) and DNA immobilized onto PVF+ modified Au electrode. PVF+ modified Au electrode was prepared by electrooxidation of poly(vinylferrocene) PVF at +0.7 V versus Ag/AgCl reference electrode. The polymer modified electrode and DNA immobilized polymer modified electrode were characterized by X-ray photoelectron (XPS), Fourier transform infrared-attenuated total reflentance (FTIR-ATR) and alternating current (AC) impedance spectroscopy. For application studies, differential pulse voltammetry (DPV) technique was used.
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    Characterization of redox polymer based electrode and electrochemical behavior for DNA detection
    (Elsevier Science Bv, 2009) Kuralay, Filiz; Erdem, Arzum; Abaci, Serdar; Ozyoruk, Haluk; Yildiz, Attila
    Characterization of redox polymer, poly(vinylferrocenium) perchlorate (PVF+ClO4-) coated as a film on Pt electrodes, and the detection of DNA based on the electrochemical behavior of the polymer were described in this study. PVF+ClO4- Modified electrodes were prepared by the electrooxidation of poly(vinylferrocene) (PVF), and DNA immobilized polymer modified electrode was then prepared. The characterization of the polymer modified electrodes were performed by scanning tunneling Microscopy (STM), Raman spectroscopy and alternating current (AC) impedance. The effects of DNA concentration. pH, and polymer films in various thicknesses based on the electrode response were also investigated. The electrochemical behavior of DNA modified polymer electrode by using double-stranded DNA (dsDNA) or single-stranded DNA (ssDNA) was compared. DNA hybridization was also investigated. (C) 2009 Elsevier B.V. All rights reserved.
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    Electrochemical characterization of redox polymer modified electrode developed for monitoring of adenine
    (Elsevier Science Bv, 2013) Kuralay, Filiz; Erdem, Arzum; Abaci, Serdar; Ozyoruk, Haluk
    Electrochemical characterization of redox polymer for monitoring of adenine was described in this study using poly(vinylferrocenium) (PVF+) modified platinum (Pt) electrode. Scanning electron microscope (SEM) was used for the surface characterization. The electrochemical behaviors of polymer modified and adenine immobilized polymer modified electrodes were investigated by using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). In order to obtain more sensitive and improved electrochemical signals, analytical parameters such as the effects of polymeric film thickness, immobilization time of adenine, pH and adenine concentration were examined on the response of the polymer modified electrode. Alternating current (AC) impedance spectroscopy was used for the characterization of polymer modified and adenine immobilized polymer modified electrodes. The effect of possible interferents on the response of the electrode was examined. (C) 2013 Elsevier B.V. All rights reserved.
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    Electrochemical determination of beta-lactoglobulin in whey proteins
    (Springer, 2020) Surucu, Ozge; Abaci, Serdar
    Determination of beta-lactoglobulin in milk products is very important because beta-lactoglobulin is the main ingredient in whey-based protein powders. However, beta-lactoglobulin is a dangerous food allergen. on such an occasion, the determination of beta-lactoglobulin is coming into prominence and electrochemistry is a good alternative for this purpose because of its simple, economic and rapid response. in this work, a graphene oxide modified pencil graphite electrode is developed to determine beta-lactoglobulin based on the current signal of known concentration of hydrogen peroxide. Cyclic voltammetry technique is performed to obtain the electrochemical behavior of beta-lactoglobulin. Linear range, limit of detection and limit of quantification were calculated according to the calibration curve of various amounts of beta-lactoglobulin. Ultraviolet-visible spectroscopy technique is also used to investigate the absorption behavior of beta-lactoglobulin in various biological macromolecules including whey proteins. the proposed graphene oxide modified pencil graphite surface is successfully applied to determine beta-lactoglobulin in real milk sample, so a new methodology based on a newly developed electrochemical technique is described as a promising alternative in diary products.
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    Non-enzymatic and Electrochemical Detection of Creatine in Food Supplements
    (Springer, 2022) Surucu, Ozge; Abaci, Serdar
    Creatine is a well-known member of supplement family and is widely preferred by consumers for therapeutic applications, muscle strength, and energy recovery. This study describes a new concept, which is based on a simple, one-step, and non-enzymatic creatine detection system on the Pt electrode. The creatine content of food supplements was determined using an elemental analyzer, and five different supplements were separated in terms of creatine. Three supplements were investigated as creatine sources, and the other two supplements were considered as branched-chain amino acid sources. For the electrochemical detection of creatine, cyclic voltammetry and square-wave voltammetry techniques were used. Graphene oxide and carbon nanotube-modified surfaces were applied in addition to bare Pt surface; however, bare Pt surface was found to be superior to the modified surfaces. Creatine was successfully detected using the proposed Pt electrode, and the limit of detection was calculated to be 36.0 mu g L-1. The obtained selectivity allowed performing a voltammetric comparison of creatine and branched-chain amino acid supplements. Real sample analysis was performed by analyzing milk powder; however, milk powder supplied only 32.4% of creatine content. This study presents a new method for detection of food supplements without the need for modification, high-cost, or pretreatment process.
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    Poly(vinylferrocenium) coated disposable pencil graphite electrode for DNA hybridization
    (Elsevier Science Inc, 2009) Kuralay, Filiz; Erdem, Arzum; Abaci, Serdar; Ozyoruk, Haluk; Yildiz, Attila
    Poly(vinylferrocenium) (PVF(+)) modified electrode was developed in this study for the electrochemical sensing of DNA based on the oxidation signals of polymer, adenine and guanine. Experimental parameters, such as; polymeric film thickness, DNA immobilization time and DNA concentration were examined in order to obtain more sensitive and selective electrochemical signals. After optimization studies, DNA hybridization was investigated. (C) 2009 Elsevier B.V. All rights reserved.
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    Preparation and characterization of zinc oxide nanoparticles and their sensor applications for electrochemical monitoring of nucleic acid hybridization
    (Elsevier Science Bv, 2011) Yumak, Tugrul; Kuralay, Filiz; Muti, Mihrican; Sinag, Ali; Erdem, Arzum; Abaci, Serdar
    In this study, ZnO nanoparticles (ZNP) of approximately 30 nm in size were synthesized by the hydrothermal method and characterized by X-ray diffraction (XRD), Braun-Emmet-Teller (BET) N(2) adsorption analysis and transmission electron microscopy (TEM). ZnO nanoparticles enriched with poly(vinylferrocenium) (PVF(+)) modified single-use graphite electrodes were then developed for the electrochemical monitoring of nucleic acid hybridization related to the Hepatitis B Virus (HBV). Firstly, the surfaces of polymer modified and polymer-ZnO nanoparticle modified single-use pencil graphite electrodes (PGEs) were characterized using scanning electron microscopy (SEM). The electrochemical behavior of these electrodes was also investigated using differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). Subsequently, the polymer-ZnO nanoparticle modified PGEs were evaluated for the electrochemical detection of DNA based on the changes at the guanine oxidation signals. Various modifications in DNA oligonucleotides and probe concentrations were examined in order to optimize the electrochemical signals that were generated by means of nucleic acid hybridization. After the optimization studies, the sequence-selective DNA hybridization was investigated in the case of a complementary amino linked probe (target), or noncomplementary (NC) sequences, or target and mismatch (MM) mixture in the ratio of (1:1). (C) 2011 Elsevier B.V. All rights reserved.
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    Preparation of gold nanoparticles/single-walled carbon nanotubes/polyaniline composite-coated electrode developed for DNA detection
    (Springer, 2015) Eksin, Ece; Bolat, Gulcin; Kuralay, Filiz; Erdem, Arzum; Abaci, Serdar
    This work details the preparation of gold nanoparticles/single-walled carbon nanotubes/polyaniline composite-modified disposable pencil graphite electrode (AuNPs/SWCNTs/PANI/PGEs), and its application for electrochemical DNA sensing. Disposable pencil graphite electrode was modified with single-walled carbon nanotubes/polyaniline composite via one-step electropolymerization of aniline solution containing well-dispersed single-walled carbon nanotubes. AuNPs were then immobilized onto the SWCNTs/PANI/PGE. Electrochemical results exhibited improved sensitivity for DNA detection with AuNPs/SWCNTs/PANI/PGE compared to the SWCNTs/PANI/PGE, PANI/PGE or unmodified PGE due to the strong interaction between AuNPs, SWCNTs, and PANI based on the effective degree of electron delocalization. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to characterize the prepared electrode. Thiol-linked ssDNA was immobilized onto the AuNPs/SWCNTs/PANI/PGE for DNA detection. Experimental parameters such as the concentration of AuNPs and ssDNA were investigated to optimize the experimental conditions.
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    The Recent Electrochemical Biosensor Technologies for Monitoring of Nucleic Acid Hybridization
    (Bentham Science Publ Ltd, 2011) Karadeniz, Hakan; Kuralay, Filiz; Abaci, Serdar; Erdem, Arzum
    Electrochemical biosensors have a key importance in many areas including clinical, biological, pharmaceutical, forensic, environmental and agricultural applications. They have the advantages of rapid, easy and low cost preparation allowing the localization of biocompound on electrodes of any size with independence of sample turbidity, high sensitivity and high selectivity. Electrochemical devices have attracted considerable interest in the development of DNA hybridization biosensors. They rely on the conversion of hybridization event into a direct electrochemical signal. Many efforts have been carried out in the detection of DNA hybridization for improving the stability, reproducibility and sensitivity. This review summarizes the advanced electrochemical methodologies involved in nucleic acid hybridization performed by using polymer technology, nanoparticles (NPs), magnetic particles, and carbon nanotubes (CNTs). The preparation of polymer modified electrodes especially including conducting polymers and their applications for DNA hybridization are given with the advantages of electrocatalysis, good electroactivity, high sensitivity and providing suitable matrix for DNA immobilization. The role of various nanomaterials in biosensors with the advantages of high surface area, fast heterogeneous electron transfer, excellent biocompatibility and enhanced signal with a good selectivity are presented. The combination of these techniques is also discussed in details.
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    Tin oxide nanoparticles-polymer modified single-use sensors for electrochemical monitoring of label-free DNA hybridization
    (Elsevier Science Bv, 2010) Muti, Mihrican; Kuralay, Filiz; Erdem, Arzum; Abaci, Serdar; Yumak, Tugrul; Sinag, Ali
    In this study. SnO2 nanoparticles (SNPs)-poly(vinylferrocenium) (PVF+) modified single-use graphite electrodes were developed for electrochemical monitoring of DNA hybridization. The surfaces of polymer modified and polymer-SNP modified pencil graphite electrodes (PGEs) were firstly characterized by using SEM analysis. The electrochemical behaviours of these electrodes were also investigated using the differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) techniques. The polymer-SNP modified PGEs were then tested for the electrochemical sensing of DNA based on the changes at the guanine oxidation signals. Experimental parameters, such as; different modifications in DNA oligonucleotides, DNA probe concentrations were examined to obtain more sensitive and selective electrochemical signals for nucleic acid hybridization. After optimization studies, DNA hybridization was investigated in the case of complementary of hepatitis B virus (HBV) probe, mismatch (MM), and noncomplementary (NC) sequences. (C) 2010 Elsevier B.V. All rights reserved.