Halit ARSLAN | Gazi University (original) (raw)

Papers by Halit ARSLAN

Research paper thumbnail of Designing an electrochemical biosensor based on tyrosinase for highly sensitive and rapid detection of bisphenol A and its derivatives

Journal of the Serbian Chemical Society

Bisphenol A (BPA) is a monomer commonly used in the production of epoxy resins, plastic bottles a... more Bisphenol A (BPA) is a monomer commonly used in the production of epoxy resins, plastic bottles and dental filling materials. Due to its chemical structure, BPA and its derivates show activity similar to the endocrine hormones. It can bind to estrogen receptors and cause neurological disturbances, even at low doses. Therefore, it is important to determine BPA and its derivatives quickly and sensitively at low concentrations. In this study, a single amperometric tyrosinase enzyme biosensor was designed for the determination of the amount of BPA, bisphenol F (BPF) and bisphenol S (BPS) monomers. Tyrosinase was immobilized onto a modified carbon paste electrode by cross-linking with glutaraldehyde. The amount of BPA (BPS and BPF) was determined directly on the reduction of quinone compound released as a result of the enzymatic reaction at ?0.15V. Km(app) value of the designed biosensor for BPA was found 0.00067 ?M, the linear operating range was 0.001?0.005 ?M (a) and 0.03?0.1 ?M (b) a...

Research paper thumbnail of A Sensitive Amperometric Biosensor Based on Carbon Dot 3-Chloropropyl-trimethoxysilane Modified Electrode for Detection of Neurotransmitter Dopamine

Journal of The Electrochemical Society

Dopamine (DA) is an important electroactive neurotransmitter. The concentration of DA in the body... more Dopamine (DA) is an important electroactive neurotransmitter. The concentration of DA in the body of a healthy person is approximately 1.0 × 10−7−1.0 × 10−3 M. A decrease in dopamine concentration is associated with Parkinson’s disease. Thus, it is important to determine the amount of dopamine in early diagnosis of Parkinson’s disease. Different methods such as immunoassay, flow injection analysis (FIA), high performance liquid chromatography (HPLC) etc could be used for determination of dopamine but they are expensive and have long determination times, and pre analytic processes. In this study, a tyrosinase based amperometric biosensor was developed with carbon paste electrode modified with carbon nano dot 3-Chloropropyl-trimethoxysilane (CDs-CPTMS) for determination of the amount of dopamine. CDs-CPTMS was synthesized for the first time. Determination of dopamine was carried out by the reduction of dopamine-o-quinone at −0.15 V versus Ag/AgCl. The effect of temperature, pH, and su...

Research paper thumbnail of Preparation of acetylcholine biosensor for the diagnosis of Alzheimer's disease

Journal of Molecular Structure, 2021

We report herein the design of a novel biosensor sensing strategy for sensitive detection of acet... more We report herein the design of a novel biosensor sensing strategy for sensitive detection of acetylcholine based on PAMAM-Sal dendrimer. PAMAM-Sal, salicylaldehyde and PAMAM dendrimer have been synthesized by means of condensation. It has been determined that PAMAM-Sal dendrimer was formed by the formation of Schiff base with FT-IR, 1 H NMR and UV spectra. In addition, the structure has been supported by elemental analysis. Later, a bienzymatic biosensor system has been developed. The bienzymatic biosensor system with acetylcholine esterase (AChE) and choline oxidase (ChO) was prepared with carbon paste electrode modified with PAMAM-Sal for determination of the amount of acetylcholine. Acetylcholine esterase and choline oxidase enzymes were immobilized onto modified carbon paste electrode by cross-linking with glutaraldehyde. Determination of acetylcholine was carried out by the oxidation of enzymatically produced H 2 O 2 at + 0.4 V vs. Ag/AgCl. The linear working range for acetylcholine determination of biosensor was identified. The effects of pH and temperature on the response of the biosensor were examined. Reusability and storage stability of the biosensor were determined. Interference effects of interferants which might be in biologic media on the response of the biosensor were also studied.

Research paper thumbnail of Polarographic investigation of tin(II), thiosemicarbazide and selenium(IV) interaction

Trace Elements and Electrolytes, 2005

Research paper thumbnail of The Effect of the Training to the Levels of Selenium and Chromium in Blood

gazi university journal of science, 2016

The purpose of this study is to investigate levels of selenium and chromium in blood in well-trai... more The purpose of this study is to investigate levels of selenium and chromium in blood in well-trained male rowers of Turkish national team during and after an aerobic maximal exercise. Eleven well-trained young male completed the exercise protocol. Blood samples were collected before the exercise, immediately after exercise, and one hour after the exercise. Blood was analyzed for Se and Cr by using inductively coupled plasma optical emission spectrometry (ICP-OES) method. Although there was no statistically changes between the pre and post Cr levels (P > 0.05), the levels observed one hour after the exercise showed statistically significant changes compared to the pre and post exercise values (P 0.05).

Research paper thumbnail of Preparation of carbon paste electrodes including poly(styrene) attached glycine–Pt(IV) for amperometric detection of glucose

Biosensors and Bioelectronics, 2014

In this study, a novel carbon paste electrode that is sensitive to glucose was prepared using the... more In this study, a novel carbon paste electrode that is sensitive to glucose was prepared using the nanoparticles modified (4-Formyl-3-methoxyphenoxymethyl) with polystyren (FMPS) with L-Glycine-Pt (IV) complexes. Polymeric nanoparticles having Pt(IV) ion were prepared from (4-Formyl-3-methoxyphenoxymethyl) polystyren, glycine and PtCl 4 by template method. Glucose oxidase enzyme was immobilized to a modified carbon paste electrode (MCPE) by cross-linking with glutaraldehyde. Determination of glucose was carried out by oxidation of enzymatically produced H 2 O 2 at 0.5 V vs. Ag/AgCl. Effects of pH and temperature were investigated, and optimum parameters were found to be 8.0 and 55 1C, respectively. Linear working range of the electrode was 5.0 Â 10 À 6-1.0 Â 10 À 3 M, R 2 ¼0.997. Storage stability and operational stability of the enzyme electrode were also studied. Glucose biosensor gave perfect reproducible results after 10 measurements with 2.3% relative standard deviation. Also, it had good storage stability (gave 53.57% of the initial amperometric response at the end of 33th day).

Research paper thumbnail of Galvanic corrosion of titanium-based dental implant materials

Journal of Applied Electrochemistry, 2008

Research paper thumbnail of Direct Determination of Copper with Thiosemicarbazide by Uv-Vis Spectrophotometric Method and Effect of Presence Some Other Cations

Gazi University Journal of Science, 2004

Normal 0 21 false false false TR X-NONE X-NONE MicrosoftInternetExplorer4 Direct determination of... more Normal 0 21 false false false TR X-NONE X-NONE MicrosoftInternetExplorer4 Direct determination of copper at the presence of Pb 2+ , Cd 2+ , Sn 2+ , Sn 4+ , Co 2+ , Ni 2+ , Fe 2+ , Fe 3+ , Cr 3+ , Cr 6+ , Zn 2+ , Mn 2+ , As 3+ , As 5+ , ions was carried out using thiosemicarbazide as complexing agent by UV-VIS spectrophotometry. The peak of Cu 2+ -thiosemicarbazide complex at 356 nm in 0.1 M HNO 3 (aq) was taken to be reference. With the application of same method to the top water, the amount of Cu 2+ , in tap water was determined to be 0.11±0,03 mg/L. This method is important as it requires no pre-seperation technique and it is sensitive upto 1.0x10-6 M. Key Words: Direct determination, Copper, UV-VIS spectrophotometry, Thiosemicarbazide.

Research paper thumbnail of Direct Determination of Copper with Thiosemicarbazide by Uv-Vis Spectrophotometric Method and Effect of Presence Some Other Cations

Gazi University Journal of Science, 2004

Normal 0 21 false false false TR X-NONE X-NONE MicrosoftInternetExplorer4 Direct determination of... more Normal 0 21 false false false TR X-NONE X-NONE MicrosoftInternetExplorer4 Direct determination of copper at the presence of Pb 2+ , Cd 2+ , Sn 2+ , Sn 4+ , Co 2+ , Ni 2+ , Fe 2+ , Fe 3+ , Cr 3+ , Cr 6+ , Zn 2+ , Mn 2+ , As 3+ , As 5+ , ions was carried out using thiosemicarbazide as complexing agent by UV-VIS spectrophotometry. The peak of Cu 2+ -thiosemicarbazide complex at 356 nm in 0.1 M HNO 3 (aq) was taken to be reference. With the application of same method to the top water, the amount of Cu 2+ , in tap water was determined to be 0.11±0,03 mg/L. This method is important as it requires no pre-seperation technique and it is sensitive upto 1.0x10-6 M. Key Words: Direct determination, Copper, UV-VIS spectrophotometry, Thiosemicarbazide.

Research paper thumbnail of Preparation of modified glassy carbon surface with N-(1-H-indole-3yl) methylene thiazole-2-amine and its characterization

Surface and Coatings Technology, 2014

N-(1-H-indole-3yl) methylene thiazole-2-amine (IMT2A) was oxidized at a glassy carbon (GC) electr... more N-(1-H-indole-3yl) methylene thiazole-2-amine (IMT2A) was oxidized at a glassy carbon (GC) electrode surface in acetonitrile containing 0.1 M tetrabutylammonium tetrafluoroborate (TBATFB) to prepare a modified electrode. Surface modification experiments were performed using cyclic voltammetry with the potential range of 0.8 to 1.6 V with a scan rate of 100 mV s −1 for 15 cycles in 1 mM IMT2A solution. The modified GC surface (IMT2A-GC) was characterized by cyclic voltammetry, electrochemical impedance spectroscopy, contact angle measurement, profilometry, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and atomic force microscopy. The number of electron transferred and diffusion coefficient of IMT2A were calculated by using an ultramicroelectrode (UME).

Research paper thumbnail of An Amperometric Biosensor for Glucose Determination Prepared from Glucose Oxidase Immobilized in Polyaniline-Polyvinylsulfonate Film

Sensors, 2011

In this study, a novel amperometric glucose biosensor with immobilization of glucose oxidase on e... more In this study, a novel amperometric glucose biosensor with immobilization of glucose oxidase on electrochemically polymerized polyaniline-polyvinylsulphonate (Pani-Pvs) films has been accomplished via the entrapment technique. Electropolymerization of aniline on the Pt surface of the Pt electrode was carried out at constant potential (0.75 V, vs. Ag/AgCl) using an electrochemical cell containing aniline and polyvinylsulphonate. Firstly, the optimum working conditions for preparing polyaniline-polyvinylsulfonate films were investigated. Determination of glucose was carried out by the oxidation of enzymatically produced H 2 O 2 at 0.4 V vs. Ag/AgCl. The effects of pH and temperature were investigated and the optimum pH value was found to be 7.5. The storage stability and operational stability of the enzyme electrode were also studied. The results show that 75% of the response current was retained after 16 activity assays. The prepared glucose biosensor retained 80.6% of initial activity after 40 days when stored in 0.1 M phosphate buffer solution at 4 °C.

Research paper thumbnail of An amperometric biosensor for choline determination prepared from choline oxidase immobilized in polypyrrole-polyvinylsulfonate film

Artificial Cells, Blood Substitutes, and Biotechnology, 2012

In this paper, a novel amperometric choline biosensor with immobilization of choline oxidase on e... more In this paper, a novel amperometric choline biosensor with immobilization of choline oxidase on electrochemically polymerized polypyrrole-polyvinylsulphonate (PPy-PVS) film has been accomplished via the entrapment technique. The effects of pH and temperature were investigated and optimum parameters were found to be 9.0 and 60 °C, respectively. There are two linear parts in the region between 1.0 × 10 (-7) - 1.0 × 10 (-6)M (R(2) = 0.997) and 1.0 × 10 (-5) - 1.0 × 10 (-3) M (R(2) = 0.986). The storage stability and operation stability of the enzyme electrode were also studied.

Research paper thumbnail of Preparation of a Polypyrrole-Polyvinylsulphonate Composite Film Biosensor for Determination of Phenol Based on Entrapment of Polyphenol Oxidase

Artificial Cells, Blood Substitutes, and Biotechnology, 2011

Abstract: In this paper, a novel amperometric phenol biosensor with immobilization of polyphenol ... more Abstract: In this paper, a novel amperometric phenol biosensor with immobilization of polyphenol oxidase (tyrosinase) on electrochemically polymerized polypyrrole-polyvinylsulphonate (PPy-PVS) film has been accomplished via the entrapment technique on the surface of a platinum electrode. The amperometric determination is based on the electrochemical reduction of quinon generated in the enzymatic reaction of phenol. The effects of pH and temperature were investigated and optimum parameters were found to be 8.0 and 30 °C, respectively. The linear working range of the electrode was 1.0 × 10(-7) - 5.0 × 10(-6) M. The storage stability and operation stability of the enzyme electrode were also studied.

Research paper thumbnail of Fenolün Elektrokimyasal Tayini

Çevre ve insan sa l aç s ndan büyük tehlike arzeden fenol’ün, bulundu u ortamlarda tayin edilebil... more Çevre ve insan sa l aç s ndan büyük tehlike arzeden fenol’ün, bulundu u ortamlarda tayin edilebilmesi oldukça önemlidir. Fenol ve fenolik bile iklerin tayin yöntemlerini, gaz kromatografisi, s v kromatografisi, kapiler elektroforez ve spektrofotometrik yöntemler olarak s ralayabiliriz [1]. Bunlar n d nda çok az da olsa elektrokimyasal yöntemlerde vard r [2]. Elektrokimyasal yöntemlerde fenol tayini genellikle biyosensörler ya da modifiye elektrotlarla gerçekle tirilmektedir [3]. Bu çal mada, fenol tayini için elektrokimyasal yöntem geli tirilmi tir. Bunun için önce fenol, katekol ve kinonun kare dalga voltametrisi (SWV) ve dönü ümlü voltametri (CV) ile elektrokimyasal davran lar çe itli elektrot ve destek elektrolitlerle incelenmi tir. Bu çal malar sonucunda en uygun elektrodun alt n (Au) elektrot ve en uygun destek elektrolitinde pH 5 asetik asit/sodyumasetat (CH3COOH/CH3COONa) tamponu oldu u görülmü tür. Bu ortamda katekol ve fenol’ün SWV ile elektrokimyasal davran lar incelendi i...

Research paper thumbnail of Development of a Novel Phenylalanine Biosensor for Diagnosis of Phenylketonuria

IEEE Sensors Journal

A new L-phenylalanine dehydrogenase (PHD) and Toluidine Blue O (TBO) based amperometric biosensor... more A new L-phenylalanine dehydrogenase (PHD) and Toluidine Blue O (TBO) based amperometric biosensor for the determination of L-phenylalanine was reported in this study. An amperometric L-phenylalanine biosensor with immobilization of TBO (as a mediator,), PDH and nicotinamide adenine dinucleotide (NAD<sup>+</sup>) onto polypyrrole-polyvinylsulphonate (PPy-PVS) film was accomplished on the surface of a platinum electrode. Cross-linking with glutaraldehyde technique was used for immobilizing PDH on PPy-PVS film. Toluidine Blue O (TBO) was used as the mediator. The changes in the anodic current at −0.195 V vs Ag/AgCl produced by TBO was proportional to the L-phenylalanine concentration changes in the sample. The effects of substrate concentration, pH and temperature on the response of the L-phenylalanine biosensor were investigated. Optimum pH and temperature were found to be 7.0 and 60 °C, respectively. The linear working region of biosensor is <inline-formula> <tex-math notation="LaTeX">${5.0}\times {10}^{- {7}}$ </tex-math></inline-formula> - <inline-formula> <tex-math notation="LaTeX">${2.5}\times {10}^{- {5}}$ </tex-math></inline-formula> M (R<sup>2</sup> = 0.9816). The detection limit of the biosensor was <inline-formula> <tex-math notation="LaTeX">${1.0}\times {10}^{- {8}}$ </tex-math></inline-formula> M and response time of the biosensor was 200 s. The storage stability and application stability of the biosensor were also studied. Several possible interfering substances’ effects on the phenylalanine biosensor were investigated. The developed biosensor was tested in determinations of content in a synthetic blood sample.

Research paper thumbnail of Development of choline biosensor using toluidine blue O as mediator

Preparative Biochemistry & Biotechnology

Abstract A new choline oxidase (ChO) and toluidine blue O (TBO) based amperometric choline biosen... more Abstract A new choline oxidase (ChO) and toluidine blue O (TBO) based amperometric choline biosensor was reported in this article. An amperometric choline biosensor with immobilization of TBO (as a mediator), ChO onto polypyrrole–polyvinylsulphonate (PPy–PVS) film was accomplished on the surface of a platinum electrode. ChO was immobilized on PPy–PVS film by cross-linking with glutaraldehyde (GA). TBO was used as the mediator. Choline is oxidized to betaine and hydrogen peroxide in an oxygenated environment by ChO. Mediator reduced by reaction with hydrogen peroxide. The amperometric response was based upon the electrocatalytic properties of TBO. Optimum pH and temperature values were 7.0 and 30 °C, respectively. There was linearity between 1.0 × 10−8 and 2.0 × 10−8 M (R2 = 0.9805). The detection limit of the biosensor was 1.0 × 10−9 M and response time of the biosensor was 200 s. The storage stability and reproducibility of the biosensor were also investigated. Interfering effect of several interferants such as ascorbic acid, uric acid, alanine, dopamine, paracetamol, cysteine, and glucose on the choline biosensor was examined. The developed biosensor was tested in determinations of content in a synthetic blood sample.

Research paper thumbnail of Electrochemical nucleic acid hybridization biosensor based on poly(L-Aspartic acid)-modified electrode for the detection of short oligonucleotide sequences related to hepatitis C virus 1a

Preparative Biochemistry and Biotechnology

Abstract This work describes, for the first time, the fabrication of poly(L-aspartic acid) (PAA) ... more Abstract This work describes, for the first time, the fabrication of poly(L-aspartic acid) (PAA) film modified pencil graphite electrode (PGE) for the detection of hepatitis C Virus 1a (HCV1a). The presence of PAA on the electrode surface can provide free carboxyl groups for covalent binding of biomolecules. The PGE surface was first coated with PAA via electropolymerization of the L-aspartic acid, and avidin was subsequently attached to the PAA modified electrode by covalent attachment. Biotinylated HCV1a probes were immobilized on avidin/PAA/PGE via avidin-biotin interaction. The morphology of PAA/PGE was examined using a scanning electron microscope. The hybridization events were monitored with square wave voltammetry using Meldola’s blue (MDB). Compared to non-complementary oligonucleotide sequences, when hybridization was carried out between the probe and its synthetic targets or the synthetic polymerase chain reaction analog of HCV1a, the highest MDB signal was observed. The linear range of the biosensor was 12.5 to 100 nM and limit of detection was calculated as 8.7 nM. The biosensor exhibited favorable stability over relatively long-term storage. All these results suggest that PAA-modified electrode can be used to nucleic acid biosensor application and electropolymerization of L-aspartic acid can be considered as a good candidate for the immobilization of biomolecules.

Research paper thumbnail of Glucose biosensor based on immobilization of glucose oxidase on a carbon paste electrode modified with microspheres attached L-glycine

Biotechnology and Applied Biochemistry, 2016

In the present study, a novel biosensor that is sensitive to glucose was prepared using the micro... more In the present study, a novel biosensor that is sensitive to glucose was prepared using the microspheres modified (4-Formyl-3-methoxyphenoxymethyl)polystyrene (FMPS) with L-Glycine (FMPS-Gly). Polymeric microspheres having Schiff bases were prepared from FMPS, Glycine condensation method. Glucose oxidase enzyme (GOx) was immobilized onto modified carbon paste electrode (MCPE) by cross-linking with glutaraldehyde. Oxidation of enzymatically produced H2 O2 (+0.5 V vs.Ag/AgCl) was used for determination of glucose. Optimal temperature and pH were found as 50°C and 8.0, respectively. The glucose biosensor showed a linear working range from 5.0×10(-4) to 1.0×10(-2) M, R(2) = 0.999. Storage and operational stability of the biosensor were also investigated. The biosensor gave perfect reproducible results after 20 measurements with 3.3 % relative standard deviation. Also, it had good storage stability. This article is protected by copyright. All rights reserved.

Research paper thumbnail of A New Laccase-Based Biosensor for Epinephrine Determination

Gazi University Journal of Science, 2015

In this paper, a novel amperometric e pinephrine (adrenaline) biosensor with immobilization of la... more In this paper, a novel amperometric e pinephrine (adrenaline) biosensor with immobilization of laccase on polypyrrole–polyvinylsulphonate (PPy-PVS) film has been a complished. Laccase enzyme were immobilized on PPy-PVS film by cross-linking with glutaraldehyde. Determination of EP was carried out by the reduction of enzymatically produced epinephrinequinone at - 0.220 V vs. Ag/AgCl. The effects of pH and temperature were investigated. There are two linear parts in the region between 0.1 µM-1.0 µM and 1.0 µM-10.0 µM. The storage stability and operation stability of the enzyme electrode were also studied. Interference effects were investigated on response of the biosensor.

Research paper thumbnail of Amperometric Detection of Glucose by Polyaniline-Activated Carbon Composite Carbon Paste Electrode

International journal of electrochemical science

In this study, a novel carbon paste electrode using the salt form of polyaniline (pani)-activated... more In this study, a novel carbon paste electrode using the salt form of polyaniline (pani)-activated carbon composite sensitive to glucose, was prepared. Glucose oxidase enzyme was immobilized to modified carbon paste electrode by cross-linking with glutaraldehyde. Determination of glucose was carried out by the oxidation of enzymatically produced H 2O 2 at 0.4 V vs. Ag/AgCl. The effects of pH and temperature were investigated and optimum parameters were found to be 5.0 and 65 oC, respectively. The linear working range of the electrode was 5.0×10 -7 - 1.0×10 -5 M, R 2 =0.980. The storage stability and operation stability of the enzyme electrode were also studied.

Research paper thumbnail of Designing an electrochemical biosensor based on tyrosinase for highly sensitive and rapid detection of bisphenol A and its derivatives

Journal of the Serbian Chemical Society

Bisphenol A (BPA) is a monomer commonly used in the production of epoxy resins, plastic bottles a... more Bisphenol A (BPA) is a monomer commonly used in the production of epoxy resins, plastic bottles and dental filling materials. Due to its chemical structure, BPA and its derivates show activity similar to the endocrine hormones. It can bind to estrogen receptors and cause neurological disturbances, even at low doses. Therefore, it is important to determine BPA and its derivatives quickly and sensitively at low concentrations. In this study, a single amperometric tyrosinase enzyme biosensor was designed for the determination of the amount of BPA, bisphenol F (BPF) and bisphenol S (BPS) monomers. Tyrosinase was immobilized onto a modified carbon paste electrode by cross-linking with glutaraldehyde. The amount of BPA (BPS and BPF) was determined directly on the reduction of quinone compound released as a result of the enzymatic reaction at ?0.15V. Km(app) value of the designed biosensor for BPA was found 0.00067 ?M, the linear operating range was 0.001?0.005 ?M (a) and 0.03?0.1 ?M (b) a...

Research paper thumbnail of A Sensitive Amperometric Biosensor Based on Carbon Dot 3-Chloropropyl-trimethoxysilane Modified Electrode for Detection of Neurotransmitter Dopamine

Journal of The Electrochemical Society

Dopamine (DA) is an important electroactive neurotransmitter. The concentration of DA in the body... more Dopamine (DA) is an important electroactive neurotransmitter. The concentration of DA in the body of a healthy person is approximately 1.0 × 10−7−1.0 × 10−3 M. A decrease in dopamine concentration is associated with Parkinson’s disease. Thus, it is important to determine the amount of dopamine in early diagnosis of Parkinson’s disease. Different methods such as immunoassay, flow injection analysis (FIA), high performance liquid chromatography (HPLC) etc could be used for determination of dopamine but they are expensive and have long determination times, and pre analytic processes. In this study, a tyrosinase based amperometric biosensor was developed with carbon paste electrode modified with carbon nano dot 3-Chloropropyl-trimethoxysilane (CDs-CPTMS) for determination of the amount of dopamine. CDs-CPTMS was synthesized for the first time. Determination of dopamine was carried out by the reduction of dopamine-o-quinone at −0.15 V versus Ag/AgCl. The effect of temperature, pH, and su...

Research paper thumbnail of Preparation of acetylcholine biosensor for the diagnosis of Alzheimer's disease

Journal of Molecular Structure, 2021

We report herein the design of a novel biosensor sensing strategy for sensitive detection of acet... more We report herein the design of a novel biosensor sensing strategy for sensitive detection of acetylcholine based on PAMAM-Sal dendrimer. PAMAM-Sal, salicylaldehyde and PAMAM dendrimer have been synthesized by means of condensation. It has been determined that PAMAM-Sal dendrimer was formed by the formation of Schiff base with FT-IR, 1 H NMR and UV spectra. In addition, the structure has been supported by elemental analysis. Later, a bienzymatic biosensor system has been developed. The bienzymatic biosensor system with acetylcholine esterase (AChE) and choline oxidase (ChO) was prepared with carbon paste electrode modified with PAMAM-Sal for determination of the amount of acetylcholine. Acetylcholine esterase and choline oxidase enzymes were immobilized onto modified carbon paste electrode by cross-linking with glutaraldehyde. Determination of acetylcholine was carried out by the oxidation of enzymatically produced H 2 O 2 at + 0.4 V vs. Ag/AgCl. The linear working range for acetylcholine determination of biosensor was identified. The effects of pH and temperature on the response of the biosensor were examined. Reusability and storage stability of the biosensor were determined. Interference effects of interferants which might be in biologic media on the response of the biosensor were also studied.

Research paper thumbnail of Polarographic investigation of tin(II), thiosemicarbazide and selenium(IV) interaction

Trace Elements and Electrolytes, 2005

Research paper thumbnail of The Effect of the Training to the Levels of Selenium and Chromium in Blood

gazi university journal of science, 2016

The purpose of this study is to investigate levels of selenium and chromium in blood in well-trai... more The purpose of this study is to investigate levels of selenium and chromium in blood in well-trained male rowers of Turkish national team during and after an aerobic maximal exercise. Eleven well-trained young male completed the exercise protocol. Blood samples were collected before the exercise, immediately after exercise, and one hour after the exercise. Blood was analyzed for Se and Cr by using inductively coupled plasma optical emission spectrometry (ICP-OES) method. Although there was no statistically changes between the pre and post Cr levels (P > 0.05), the levels observed one hour after the exercise showed statistically significant changes compared to the pre and post exercise values (P 0.05).

Research paper thumbnail of Preparation of carbon paste electrodes including poly(styrene) attached glycine–Pt(IV) for amperometric detection of glucose

Biosensors and Bioelectronics, 2014

In this study, a novel carbon paste electrode that is sensitive to glucose was prepared using the... more In this study, a novel carbon paste electrode that is sensitive to glucose was prepared using the nanoparticles modified (4-Formyl-3-methoxyphenoxymethyl) with polystyren (FMPS) with L-Glycine-Pt (IV) complexes. Polymeric nanoparticles having Pt(IV) ion were prepared from (4-Formyl-3-methoxyphenoxymethyl) polystyren, glycine and PtCl 4 by template method. Glucose oxidase enzyme was immobilized to a modified carbon paste electrode (MCPE) by cross-linking with glutaraldehyde. Determination of glucose was carried out by oxidation of enzymatically produced H 2 O 2 at 0.5 V vs. Ag/AgCl. Effects of pH and temperature were investigated, and optimum parameters were found to be 8.0 and 55 1C, respectively. Linear working range of the electrode was 5.0 Â 10 À 6-1.0 Â 10 À 3 M, R 2 ¼0.997. Storage stability and operational stability of the enzyme electrode were also studied. Glucose biosensor gave perfect reproducible results after 10 measurements with 2.3% relative standard deviation. Also, it had good storage stability (gave 53.57% of the initial amperometric response at the end of 33th day).

Research paper thumbnail of Galvanic corrosion of titanium-based dental implant materials

Journal of Applied Electrochemistry, 2008

Research paper thumbnail of Direct Determination of Copper with Thiosemicarbazide by Uv-Vis Spectrophotometric Method and Effect of Presence Some Other Cations

Gazi University Journal of Science, 2004

Normal 0 21 false false false TR X-NONE X-NONE MicrosoftInternetExplorer4 Direct determination of... more Normal 0 21 false false false TR X-NONE X-NONE MicrosoftInternetExplorer4 Direct determination of copper at the presence of Pb 2+ , Cd 2+ , Sn 2+ , Sn 4+ , Co 2+ , Ni 2+ , Fe 2+ , Fe 3+ , Cr 3+ , Cr 6+ , Zn 2+ , Mn 2+ , As 3+ , As 5+ , ions was carried out using thiosemicarbazide as complexing agent by UV-VIS spectrophotometry. The peak of Cu 2+ -thiosemicarbazide complex at 356 nm in 0.1 M HNO 3 (aq) was taken to be reference. With the application of same method to the top water, the amount of Cu 2+ , in tap water was determined to be 0.11±0,03 mg/L. This method is important as it requires no pre-seperation technique and it is sensitive upto 1.0x10-6 M. Key Words: Direct determination, Copper, UV-VIS spectrophotometry, Thiosemicarbazide.

Research paper thumbnail of Direct Determination of Copper with Thiosemicarbazide by Uv-Vis Spectrophotometric Method and Effect of Presence Some Other Cations

Gazi University Journal of Science, 2004

Normal 0 21 false false false TR X-NONE X-NONE MicrosoftInternetExplorer4 Direct determination of... more Normal 0 21 false false false TR X-NONE X-NONE MicrosoftInternetExplorer4 Direct determination of copper at the presence of Pb 2+ , Cd 2+ , Sn 2+ , Sn 4+ , Co 2+ , Ni 2+ , Fe 2+ , Fe 3+ , Cr 3+ , Cr 6+ , Zn 2+ , Mn 2+ , As 3+ , As 5+ , ions was carried out using thiosemicarbazide as complexing agent by UV-VIS spectrophotometry. The peak of Cu 2+ -thiosemicarbazide complex at 356 nm in 0.1 M HNO 3 (aq) was taken to be reference. With the application of same method to the top water, the amount of Cu 2+ , in tap water was determined to be 0.11±0,03 mg/L. This method is important as it requires no pre-seperation technique and it is sensitive upto 1.0x10-6 M. Key Words: Direct determination, Copper, UV-VIS spectrophotometry, Thiosemicarbazide.

Research paper thumbnail of Preparation of modified glassy carbon surface with N-(1-H-indole-3yl) methylene thiazole-2-amine and its characterization

Surface and Coatings Technology, 2014

N-(1-H-indole-3yl) methylene thiazole-2-amine (IMT2A) was oxidized at a glassy carbon (GC) electr... more N-(1-H-indole-3yl) methylene thiazole-2-amine (IMT2A) was oxidized at a glassy carbon (GC) electrode surface in acetonitrile containing 0.1 M tetrabutylammonium tetrafluoroborate (TBATFB) to prepare a modified electrode. Surface modification experiments were performed using cyclic voltammetry with the potential range of 0.8 to 1.6 V with a scan rate of 100 mV s −1 for 15 cycles in 1 mM IMT2A solution. The modified GC surface (IMT2A-GC) was characterized by cyclic voltammetry, electrochemical impedance spectroscopy, contact angle measurement, profilometry, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and atomic force microscopy. The number of electron transferred and diffusion coefficient of IMT2A were calculated by using an ultramicroelectrode (UME).

Research paper thumbnail of An Amperometric Biosensor for Glucose Determination Prepared from Glucose Oxidase Immobilized in Polyaniline-Polyvinylsulfonate Film

Sensors, 2011

In this study, a novel amperometric glucose biosensor with immobilization of glucose oxidase on e... more In this study, a novel amperometric glucose biosensor with immobilization of glucose oxidase on electrochemically polymerized polyaniline-polyvinylsulphonate (Pani-Pvs) films has been accomplished via the entrapment technique. Electropolymerization of aniline on the Pt surface of the Pt electrode was carried out at constant potential (0.75 V, vs. Ag/AgCl) using an electrochemical cell containing aniline and polyvinylsulphonate. Firstly, the optimum working conditions for preparing polyaniline-polyvinylsulfonate films were investigated. Determination of glucose was carried out by the oxidation of enzymatically produced H 2 O 2 at 0.4 V vs. Ag/AgCl. The effects of pH and temperature were investigated and the optimum pH value was found to be 7.5. The storage stability and operational stability of the enzyme electrode were also studied. The results show that 75% of the response current was retained after 16 activity assays. The prepared glucose biosensor retained 80.6% of initial activity after 40 days when stored in 0.1 M phosphate buffer solution at 4 °C.

Research paper thumbnail of An amperometric biosensor for choline determination prepared from choline oxidase immobilized in polypyrrole-polyvinylsulfonate film

Artificial Cells, Blood Substitutes, and Biotechnology, 2012

In this paper, a novel amperometric choline biosensor with immobilization of choline oxidase on e... more In this paper, a novel amperometric choline biosensor with immobilization of choline oxidase on electrochemically polymerized polypyrrole-polyvinylsulphonate (PPy-PVS) film has been accomplished via the entrapment technique. The effects of pH and temperature were investigated and optimum parameters were found to be 9.0 and 60 °C, respectively. There are two linear parts in the region between 1.0 × 10 (-7) - 1.0 × 10 (-6)M (R(2) = 0.997) and 1.0 × 10 (-5) - 1.0 × 10 (-3) M (R(2) = 0.986). The storage stability and operation stability of the enzyme electrode were also studied.

Research paper thumbnail of Preparation of a Polypyrrole-Polyvinylsulphonate Composite Film Biosensor for Determination of Phenol Based on Entrapment of Polyphenol Oxidase

Artificial Cells, Blood Substitutes, and Biotechnology, 2011

Abstract: In this paper, a novel amperometric phenol biosensor with immobilization of polyphenol ... more Abstract: In this paper, a novel amperometric phenol biosensor with immobilization of polyphenol oxidase (tyrosinase) on electrochemically polymerized polypyrrole-polyvinylsulphonate (PPy-PVS) film has been accomplished via the entrapment technique on the surface of a platinum electrode. The amperometric determination is based on the electrochemical reduction of quinon generated in the enzymatic reaction of phenol. The effects of pH and temperature were investigated and optimum parameters were found to be 8.0 and 30 °C, respectively. The linear working range of the electrode was 1.0 × 10(-7) - 5.0 × 10(-6) M. The storage stability and operation stability of the enzyme electrode were also studied.

Research paper thumbnail of Fenolün Elektrokimyasal Tayini

Çevre ve insan sa l aç s ndan büyük tehlike arzeden fenol’ün, bulundu u ortamlarda tayin edilebil... more Çevre ve insan sa l aç s ndan büyük tehlike arzeden fenol’ün, bulundu u ortamlarda tayin edilebilmesi oldukça önemlidir. Fenol ve fenolik bile iklerin tayin yöntemlerini, gaz kromatografisi, s v kromatografisi, kapiler elektroforez ve spektrofotometrik yöntemler olarak s ralayabiliriz [1]. Bunlar n d nda çok az da olsa elektrokimyasal yöntemlerde vard r [2]. Elektrokimyasal yöntemlerde fenol tayini genellikle biyosensörler ya da modifiye elektrotlarla gerçekle tirilmektedir [3]. Bu çal mada, fenol tayini için elektrokimyasal yöntem geli tirilmi tir. Bunun için önce fenol, katekol ve kinonun kare dalga voltametrisi (SWV) ve dönü ümlü voltametri (CV) ile elektrokimyasal davran lar çe itli elektrot ve destek elektrolitlerle incelenmi tir. Bu çal malar sonucunda en uygun elektrodun alt n (Au) elektrot ve en uygun destek elektrolitinde pH 5 asetik asit/sodyumasetat (CH3COOH/CH3COONa) tamponu oldu u görülmü tür. Bu ortamda katekol ve fenol’ün SWV ile elektrokimyasal davran lar incelendi i...

Research paper thumbnail of Development of a Novel Phenylalanine Biosensor for Diagnosis of Phenylketonuria

IEEE Sensors Journal

A new L-phenylalanine dehydrogenase (PHD) and Toluidine Blue O (TBO) based amperometric biosensor... more A new L-phenylalanine dehydrogenase (PHD) and Toluidine Blue O (TBO) based amperometric biosensor for the determination of L-phenylalanine was reported in this study. An amperometric L-phenylalanine biosensor with immobilization of TBO (as a mediator,), PDH and nicotinamide adenine dinucleotide (NAD<sup>+</sup>) onto polypyrrole-polyvinylsulphonate (PPy-PVS) film was accomplished on the surface of a platinum electrode. Cross-linking with glutaraldehyde technique was used for immobilizing PDH on PPy-PVS film. Toluidine Blue O (TBO) was used as the mediator. The changes in the anodic current at −0.195 V vs Ag/AgCl produced by TBO was proportional to the L-phenylalanine concentration changes in the sample. The effects of substrate concentration, pH and temperature on the response of the L-phenylalanine biosensor were investigated. Optimum pH and temperature were found to be 7.0 and 60 °C, respectively. The linear working region of biosensor is <inline-formula> <tex-math notation="LaTeX">${5.0}\times {10}^{- {7}}$ </tex-math></inline-formula> - <inline-formula> <tex-math notation="LaTeX">${2.5}\times {10}^{- {5}}$ </tex-math></inline-formula> M (R<sup>2</sup> = 0.9816). The detection limit of the biosensor was <inline-formula> <tex-math notation="LaTeX">${1.0}\times {10}^{- {8}}$ </tex-math></inline-formula> M and response time of the biosensor was 200 s. The storage stability and application stability of the biosensor were also studied. Several possible interfering substances’ effects on the phenylalanine biosensor were investigated. The developed biosensor was tested in determinations of content in a synthetic blood sample.

Research paper thumbnail of Development of choline biosensor using toluidine blue O as mediator

Preparative Biochemistry & Biotechnology

Abstract A new choline oxidase (ChO) and toluidine blue O (TBO) based amperometric choline biosen... more Abstract A new choline oxidase (ChO) and toluidine blue O (TBO) based amperometric choline biosensor was reported in this article. An amperometric choline biosensor with immobilization of TBO (as a mediator), ChO onto polypyrrole–polyvinylsulphonate (PPy–PVS) film was accomplished on the surface of a platinum electrode. ChO was immobilized on PPy–PVS film by cross-linking with glutaraldehyde (GA). TBO was used as the mediator. Choline is oxidized to betaine and hydrogen peroxide in an oxygenated environment by ChO. Mediator reduced by reaction with hydrogen peroxide. The amperometric response was based upon the electrocatalytic properties of TBO. Optimum pH and temperature values were 7.0 and 30 °C, respectively. There was linearity between 1.0 × 10−8 and 2.0 × 10−8 M (R2 = 0.9805). The detection limit of the biosensor was 1.0 × 10−9 M and response time of the biosensor was 200 s. The storage stability and reproducibility of the biosensor were also investigated. Interfering effect of several interferants such as ascorbic acid, uric acid, alanine, dopamine, paracetamol, cysteine, and glucose on the choline biosensor was examined. The developed biosensor was tested in determinations of content in a synthetic blood sample.

Research paper thumbnail of Electrochemical nucleic acid hybridization biosensor based on poly(L-Aspartic acid)-modified electrode for the detection of short oligonucleotide sequences related to hepatitis C virus 1a

Preparative Biochemistry and Biotechnology

Abstract This work describes, for the first time, the fabrication of poly(L-aspartic acid) (PAA) ... more Abstract This work describes, for the first time, the fabrication of poly(L-aspartic acid) (PAA) film modified pencil graphite electrode (PGE) for the detection of hepatitis C Virus 1a (HCV1a). The presence of PAA on the electrode surface can provide free carboxyl groups for covalent binding of biomolecules. The PGE surface was first coated with PAA via electropolymerization of the L-aspartic acid, and avidin was subsequently attached to the PAA modified electrode by covalent attachment. Biotinylated HCV1a probes were immobilized on avidin/PAA/PGE via avidin-biotin interaction. The morphology of PAA/PGE was examined using a scanning electron microscope. The hybridization events were monitored with square wave voltammetry using Meldola’s blue (MDB). Compared to non-complementary oligonucleotide sequences, when hybridization was carried out between the probe and its synthetic targets or the synthetic polymerase chain reaction analog of HCV1a, the highest MDB signal was observed. The linear range of the biosensor was 12.5 to 100 nM and limit of detection was calculated as 8.7 nM. The biosensor exhibited favorable stability over relatively long-term storage. All these results suggest that PAA-modified electrode can be used to nucleic acid biosensor application and electropolymerization of L-aspartic acid can be considered as a good candidate for the immobilization of biomolecules.

Research paper thumbnail of Glucose biosensor based on immobilization of glucose oxidase on a carbon paste electrode modified with microspheres attached L-glycine

Biotechnology and Applied Biochemistry, 2016

In the present study, a novel biosensor that is sensitive to glucose was prepared using the micro... more In the present study, a novel biosensor that is sensitive to glucose was prepared using the microspheres modified (4-Formyl-3-methoxyphenoxymethyl)polystyrene (FMPS) with L-Glycine (FMPS-Gly). Polymeric microspheres having Schiff bases were prepared from FMPS, Glycine condensation method. Glucose oxidase enzyme (GOx) was immobilized onto modified carbon paste electrode (MCPE) by cross-linking with glutaraldehyde. Oxidation of enzymatically produced H2 O2 (+0.5 V vs.Ag/AgCl) was used for determination of glucose. Optimal temperature and pH were found as 50°C and 8.0, respectively. The glucose biosensor showed a linear working range from 5.0×10(-4) to 1.0×10(-2) M, R(2) = 0.999. Storage and operational stability of the biosensor were also investigated. The biosensor gave perfect reproducible results after 20 measurements with 3.3 % relative standard deviation. Also, it had good storage stability. This article is protected by copyright. All rights reserved.

Research paper thumbnail of A New Laccase-Based Biosensor for Epinephrine Determination

Gazi University Journal of Science, 2015

In this paper, a novel amperometric e pinephrine (adrenaline) biosensor with immobilization of la... more In this paper, a novel amperometric e pinephrine (adrenaline) biosensor with immobilization of laccase on polypyrrole–polyvinylsulphonate (PPy-PVS) film has been a complished. Laccase enzyme were immobilized on PPy-PVS film by cross-linking with glutaraldehyde. Determination of EP was carried out by the reduction of enzymatically produced epinephrinequinone at - 0.220 V vs. Ag/AgCl. The effects of pH and temperature were investigated. There are two linear parts in the region between 0.1 µM-1.0 µM and 1.0 µM-10.0 µM. The storage stability and operation stability of the enzyme electrode were also studied. Interference effects were investigated on response of the biosensor.

Research paper thumbnail of Amperometric Detection of Glucose by Polyaniline-Activated Carbon Composite Carbon Paste Electrode

International journal of electrochemical science

In this study, a novel carbon paste electrode using the salt form of polyaniline (pani)-activated... more In this study, a novel carbon paste electrode using the salt form of polyaniline (pani)-activated carbon composite sensitive to glucose, was prepared. Glucose oxidase enzyme was immobilized to modified carbon paste electrode by cross-linking with glutaraldehyde. Determination of glucose was carried out by the oxidation of enzymatically produced H 2O 2 at 0.4 V vs. Ag/AgCl. The effects of pH and temperature were investigated and optimum parameters were found to be 5.0 and 65 oC, respectively. The linear working range of the electrode was 5.0×10 -7 - 1.0×10 -5 M, R 2 =0.980. The storage stability and operation stability of the enzyme electrode were also studied.