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A novel dual channel responsive zinc(II) probe
(Pergamon-Elsevier Science Ltd, 2014) Karakaya, Serkan; Algi, Fatih
A novel compound, 1, which is based on a 1,10-phenanthroline scaffold with cofacial BODIPY units, is synthesized via a three-step reaction sequence. It is noteworthy that 1 can be utilized for both visual and turn-off fluorometric detection of Zn2+ ions in aqueous acetonitrile solution. The fluorescence response is based on cation-mediated oxidative photoinduced electron transfer (PET). The digital action of a two-input NOR logic gate is also demonstrated. (C) 2014 Elsevier Ltd. All rights reserved.
A novel enzyme-free FI-amperometric glucose biosensor at Cu nanoparticles modified graphite pencil electrode
(Elsevier, 2020) Ayaz, Selen; Karakaya, Serkan; Emir, Gamze; Dilgin, Didem Giray; Dilgin, Yusuf
In this work, graphite pencil electrode (GPE) was modified with Cu nanoparticles (CuNPs) for enzyme-free flow injection (FI) amperometric detection of glucose. To modify electrode, CuNPs were electrodeposited onto GPE surface by recording 10 successive cyclic voltammograms (CVs) of 2.0 mM Cu(NO3)(2) in 100 mM KNO3. The electrochemical characterizations of the electrodes were realized by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry techniques. The SEM images and EDX spectra of the pencil leads were recorded to investigate the surface morphologies of the electrodes. Then, the electrochemical response of both unmodified GPE and CuNPs/GPE towards electrochemical oxidation of glucose was performed by recording CVs in the supporting electrolyte consisted of 100 mM NaOH and 100 mM KCl. CVs recorded at GPE showed that the electron transfer rate of glucose is relatively slow and oxidation of glucose irreversibly observed with very low current at a high positive potential (+ 0.70 V). On the other hand, glucose oxidized at more negative potential value ( + 0.45 V) than that of unmodified GPE with a view of sharp peak at CuNPs/GPE. These results show that CuNPs/GPE exhibits excellent electrocatalytic activity and high electrochemical response towards oxidation of glucose because electron transfer rate of glucose was remarkably enhanced by modification of GPE with CuNPs. In the flow injection (FI) amperometric experiments, + 0.45 V and 2.5 mL/min were used as optimal values for applied potential (E-ap) and flow rate (f(r)), respectively. A linear calibration curve was obtained in the range from 0.10 to 400 mu M glucose with a detection limit and sensitivity of 0.04 mu M and 0.830 mu A mu M-1 cm(-2), respectively. The selectivity of glucose sensor was tested in the presence of various interferences. At last step, constructed glucose biosensor was successfully tested on some real glucose samples.
A Novel Sensitive and Selective Amperometric Detection Platform for the Vanillin Content in Real Samples
(Wiley, 2021) Karakaya, Serkan; Kaya, İsmet
Accurate and sensitive determination of vanillin in commercial samples is significant for food safety & quality. In the proposed study, copper particles were coated on an indium tin oxide electrode (ITO) by cyclic voltammetry (CV) for the determination of vanillin in food samples. CV studies indicated that the electrodeposition of Cu particles provides a good electrocatalytic effect towards the oxidation of vanillin. The fabricated sensor determines vanillin linearly between 0.50 μM–2.0 mM (Limit of detection: 0.15 μM). The Cu/ITO was successfully tested on vanillin samples and the recommended method provides accurate and selective determination of vanillin in daily samples.
An electrochemical detection platform for selective and sensitive voltammetric determination of quercetin dosage in a food supplement by poly(9-(2-(pyren-1-yl)ethyl)-9h-carbazole) coated indium tin oxide electrode
(Elsevier, 2021) Karakaya, Serkan; Kaya, İsmet
In proposed study, a novel compound containing carbazole (Carb) and pyrene (Pyr) units was synthesized and polymerized onto an indium tin oxide (ITO) electrode for selective and sensitive voltammetric determination of Quercetin (QCT). The characterization studies of the synthesized 9-(2-(pyren-1-yl) ethyl)-9H-carbazole (Pyr- Carb) were performed by NMR, LC-MS/MS, UV–Vis, Fluorescence and FT-IR measurements. Then, Pyr-Carb was electro-polymerized onto ITO by recording its cyclic voltammograms (CVs). Electro-oxidation behavior of QCT was investigated at bare ITO and poly (Pyr-Carb)/ITO by cyclic voltammetry (CV). The voltammetric mea- surements showed that the oxidation current of QCT significantly increased after electro polymerization of Pyr- Carb on the ITO surface. The range of linearity (ROL) and detection limit (DL) were found as 2.0–500 μM and 0.59 μM, respectively. The fabricated sensor was successfully tested on a Quercetin food supplement, and the obtained results indicated that the fabricated method enables sensitive, selective and accurate determination of QCT in real samples.
Boradiaza-s-Indasen ve tetraazasiklododekan ikilisinden oluşan yeni supramoleküler yapıların tasarımı, sentezi ve özellikleri
(Çanakkale Onsekiz Mart Üniversitesi, 2013) Karakaya, Serkan; Algı, Fatih
Yeni fonksiyonel organik bileşiklerin tasarımı ve sentezi, bu bileşiklerden elde edilen malzemelerden yararlanılarak moleküler elektronik ve fotonikler, algılayıcılar, makine ve aygıtlar, ışık yayan diyotlar (LED?ler), güneş pilleri, transistörler, elektrokromik cihazlar, veri işleme ve depolama aygıtları gibi ileri teknolojik uygulamalar nedeniyle oldukça önem arz etmektedir. Fonksiyonel organik bileşikler içerisinde lüminesans bileşikler, son zamanlarda hem biyo- ve nanoteknoloji ve çevre bilimleri, hem de malzeme bilimlerinde iyon ve/veya molekül tanıyan algılayıcılar, elektron ve/veya enerji aktarım sistemleri, görüntüleme ajanları, moleküler makina ve aygıtlar, aritmetik işlem yapabilen moleküler mantık kapıları vb. olarak kullanılabilir olmaları nedeniyle çok ilgi çekmektedir. Bu vesileyle dünyanın dört bir yanında başta sentetik organik kimya olmak üzere araştırma grupları uygulamaya açık yeni lüminesans bileşiklerin tasarımı, sentezi ve tanımlanmasına yönelik çalışmalara geniş bir yer ve önem vermektedirler. Bu çalışma, literatürde bilinmeyen, 4,4-Difloro-8-(1,4,7,10-tetraazasiklododekan)metil-1,3,5,7-tetrametil-2,6-dietil-4-bora-3a,4a-diaza-s-indasen (1) sentezlenmiş ve bu bileşiğin yapı ve özellikleri spektroskopik yöntemlerle (UV-vis, lüminesans -floresans, FTIR, NMR, elementel analiz, kütle) aydınlatılmıştır. Ayrıca elde edilen bu yeni bileşiğin iyonlara karşı duyarlılığı denenmiştir. Çalışmanın son aşamasında ise ilgili bileşikten üç yeni supramoleküler yapı (53-55) sentezlenmiş, yapıları aydınlatılmış ve anyonlara karşı duyarlılıkları incelenmiştir. Anahtar sözcükler: Lüminesans, supramoleküler kimya, sentez tasarımı, boradiaza-s-indasen (bodipy), 1,4,7,10-tetraazasiklododekan, moleküler algılayıcı, metal kompleksi.
Development and application of a sensitive, disposable and low-cost electrochemical sensing platform for an antimalarial drug: amodiaquine based on poly(calcein)-modified pencil graphite electrode
(Taylor & Francis Ltd, 2022) Karakaya, Serkan; Kartal, Burcu; Dilgin, Yusuf
In this study, an electrochemical sensor towards the determination of an antimalarial drug, amodiaquine (Adqn), was performed. The proposed sensor was fabricated by electro-polymerisation of calcein (CCN) onto pencil graphite electrode (PGE). The electrochemical behaviour of 0.40 mM Adqn at both poly(calcein)-modified pencil graphite electrode (poly(CCN)/PGE) and bare PGE was evaluated in pH 3.0 Britton-Robinson buffer solution by cyclic voltammetry (CV) method. The voltammograms indicated that poly(CCN)/PGE presents a remarkable response towards oxidation and reduction of Adqn compared with PGE. The characterisation studies at poly(CCN)/PGE were performed by recording the electrochemical impedance curves, scanning electron microscopy images and energy-dispersive X-ray spectra. To determine the analytical performance of the poly(CCN)/PGE, the parameters such as linear range, limit of detection and sensitivity were determined based on the oxidation of Adqn by differential pulse voltammetry (DPV) method and were calculated to be 0.50-25 mu M, 0.16 mu M and 20.566 mu A mu M-1, respectively. The recovery studies at poly(CCN)/PGE were carried out with various matrixes (tap water, artificial blood and maternal milk) by DPV-spike methods, and the high recovery values (99.2-100.6%) confirmed that poly(CCN)/PGE can be used towards sensitive and accurate determination of Adqn in different sample matrixes containing Adqn.
Development of an amperometric hydrazine sensor at a disposable poly(alizarin red S) modified pencil graphite electrode
(Springer Wien, 2019) Karakaya, Serkan
In the present study, electrocatalytic oxidation of hydrazine was examined by both cyclic voltammetry and amperometry methods at a disposable, poly(alizarin red S) modified pencil graphite electrode (poly(ALS)/PGE) for the first time. Electrochemical behaviors of both bare PGE and poly(ALS)/PGE were tested by cyclic voltammetry towards 1.0 mM hydrazine in pH 9.0 Britton-Robinson buffer solution. Cyclic voltammograms showed that the oxidation peak potential of hydrazine at PGE (+ 0.70 V) was significantly reduced at poly(ALS)/PGE (+ 0.35 V) and also, a significant increment in oxidation current was observed. The recorded CVs confirmed that poly(ALS) shows high electrocatalytic effect towards oxidation of hydrazine. Secondly, the effects of monomer concentration, cycle number used in electropolymerization step and pH value of supporting solution on oxidation current of hydrazine were also optimized and found to be 1.0 mM, 5 cycle, and pH 10.0, respectively. The designed sensor shows a wide linear response range between 1.0 and 600 mu M hydrazine with a LOD of 0.28 mu M and a sensitivity of 833 mu A mM(-1) cm(-2). The selectivity property of the poly(ALS)/PGE was tested in presence of various interferences. Applicability studies of the poly(ALS)/PGE were also performed on different water samples and high recovery values (95-108%) were obtained. [GRAPHICS]
Development of an interference-minimized amperometric-FIA glucose biosensor at a pyrocatechol violet/glucose dehydrogenase-modified graphite pencil electrode
(Springer International Publishing Ag, 2020) Guenes, Mehmet; Karakaya, Serkan; Dilgin, Yusuf
A modified disposable electrode formed by immobilization of glucose dehydrogenase (DHG) onto pyrocatechol violet (Pcv)-modified graphite pencil electrode (GPE) was proposed for the flow injection (FI) amperometric glucose biosensor. Cyclic voltammetric experiments show that Pcv illustrates a good electrocatalytic effect towards the oxidation of enzymatically produced NADH. Although electrocatalytic oxidation of enzymatically generated NADH at the DHG/Poly-Pcv/GPE was successfully performed at + 250 mV in FIA system, some molecules such as ascorbic acid (AA), dopamine (DA) and uric acid (UA) give a significant positive interference due to their oxidation at this working potential. To overcome these interferences, an injector filled with a pre-oxidant, sodium bismuthate (NaBiO3), was used in the FI amperometric glucose biosensor at the DHG/Poly-Pcv/GPE. Results showed that the interferences of these molecules were significantly minimized, because they were oxidized by NaBiO3 in the injector before reaching the electrode surface in the flow cell. The constructed biosensor showed that a linear calibration curve was obtained in the range between 5.0 mu M and 500 mu M glucose with a detection limit of 1.2 mu M. This proposed glucose biosensor including elimination of interferences of some oxidizable species was successfully applied to the real and artificial samples.
Differential pulse voltammetric determination of acyclovir in pharmaceutical preparations using a pencil graphite electrode
(Elsevier Science Bv, 2016) Dilgin, Didem Giray; Karakaya, Serkan
In this study, a new selective and sensitive voltammetric procedure for determination of acyclovir (ACV) was proposed using a disposable electrode, pencil graphite electrode (PGE). Cyclic and differential pulse voltammograms of ACV were recorded in Britton-Robinson buffer solution containing 0.10 M KCI with pH of 4.0 at PGE. The PGE displayed a very good electrochemical behavior with significant enhancement of the peak current compared to a glassy carbon electrode (GCE). Under experimental conditions, the PGE had a linear response range from 1.0 mu M to 100.0 mu M ACV with a detection limit of 0.3 mu M (based on 3 S-b). Relative standard deviations of 4.8 and 3.6% were obtained for five successive determinations of 10.0 and 50.0 mu M ACV, respectively, which indicate acceptable repeatability. This voltammetric method was successfully applied to the direct determination of ACV in real pharmaceutical samples. The effect of various interfering compounds on the ACV peak current was studied. (C) 2016 Elsevier B.V. All rights reserved.
Disposable and Sensitive Electrochemical Determination of Molnupiravir at a Pencil Graphite Electrode (PGE) by Differential Pulse Voltammetry (DPV)
(Taylor and Francis Ltd., 2023) Karakaya, Serkan; Dilgin, Yusuf
This study describes the sensitive voltammetric determination of the COVID-19 drug, molnupiravir, at a pencil graphite electrode (PGE) which is easily available, inexpensive, disposable, and highly electrochemically active. For comparison purposes, cyclic and differential pulse voltammetric responses of molnupiravir were compared at the carbon paste electrode (CPE) and glassy carbon electrode (GCE). The results show that the oxidation potential of molnupiravir shifts to a more negative direction and the peak current of molnupiravir increases significantly with the PGE compared to the CPE and GCE. The PGE demonstrates remarkable electrocatalysis upon the oxidation of molnupiravir. The detection limit and linear range for molnupiravir were determined to be 7.2 nM and 25 to 1000 nM by differential pulse voltammetry. In addition, the selectivity of PGE is high for molnupiravir. The applicability of the sensor was examined by the analysis of pharmaceutical and artificial blood samples. This low-cost and practical sensor was demonstrated to determine molnupiravir with good accuracy and precision.
Electrocatalytic oxidation and flow injection analysis of formaldehyde at binary metal oxides (Co3O4-NiO and CuO-Co3O4) modified pencil graphite electrodes
(Springer, 2021) Emir, Gamze; Karakaya, Serkan; Ayaz, Selen; Dilgin, Didem Giray; Dilgin, Yusuf
In this work, a highly efficient performance of bimetallic thin films as their oxide forms (Co3O4-NiO and CuO-Co3O4) modified on pencil graphite electrodes (PGEs) was presented for electrocatalytic oxidation of formaldehyde. In addition, a sensitive and selective amperometric determination of formaldehyde in flow injection analysis system have been first performed using binary transition metal oxides modified PGEs. Co3O4-NiO and CuO-Co3O4 films were electrochemically deposited on the PGE surface using cyclic voltammetric procedures. The recorded cyclic voltammograms in the presence of formaldehyde in 0.10 M NaOH containing 0.10 M KCl showed that the prepared binary transition metal oxides modified PGEs exhibited a higher electrocatalytic activity than single metal oxide thin films modified PGEs towards oxidation of formaldehyde. The linear responses based on electrocatalytic oxidation of formaldehyde were determined as 2.5-5000 mu M and 0.25-1000 mu M for Co3O4-NiO/PGE and CuO-Co3O4/PGE, respectively. Moreover, limit of detections and sensitivities were estimated as 0.73 mu M and 81.8 mu A mM(-1) cm(-2) and 0.09 mu M and 166 mu A mM(-1) cm(-2) for Co3O4-NiO/PGE and CuO-Co3O4/PGE, respectively. The results from real sample studies proved that the fabricated FI-amperometric sensors enable high applicability towards determination of formaldehyde in real water samples.
Electrochemical enzymatic nanobiosensors of pesticides
(Elsevier, 2024) Dilgin, Yusuf; Karakaya, Serkan; Dilgin, Didem; Hanbeyoğlu, Ayşe
Pesticides have widespread applications in agriculture and industries worldwide. They are used to protect crops from weeds and insects and increase crop yields owing to their high insecticidal activity. Thanks to these applications, pesticide residues and metabolites can easily pass directly or indirectly to water, soil, and food. However, these substances are among the most important environmental pollutants that threaten human health due to their high toxicity. Therefore it is important to determine the pesticides and their residues in environmental samples and monitor their levels. Many methods, such as chromatographic, spectroscopic, and electrochemical methods, have been developed to detect pesticides. Among these, electrochemical methods have attracted attention because of their simple sample preparation and design, low cost, high sensitivity, and rapid determination response. Although it is possible to determine pesticides directly by voltammetry or electrochemical impedance-based methods, enzyme-based biosensors have been used quite frequently in the environmental monitoring of pesticides in the last few years. Recently, electrochemical nanobiosensors have been developed, including enzyme immobilization on nanomaterial-modified electrodes. These devices are widely used to perform highly sensitive pesticide determination. Electrochemical biosensors developed for the detection of pesticides often rely on measurements of (1) enzyme inhibition or (2) direct measurement of compounds produced or involved in enzymatic reactions. Acetylcholinesterase, butyrylcholinesterase, tyrosinase, alkaline phosphatase, and cholinesterase-choline oxidase multienzyme are widely used as pesticide biosensors owing to their inhibitory activities. On the other hand, organophosphorus hydrolase is used in enzyme-catalyzed reactions for the direct detection of electroactive compounds produced, depending on the pesticide concentration by enzymatic reaction. In this chapter, recent developments in enzyme-based electrochemical pesticide biosensors using nanomaterials such as carbon nanomaterials, metal or metal oxide nanoparticles, metal-organic frameworks, and their hybrids or composites (especially based on the inhibition of the enzyme by pesticides) are discussed. © 2024 Elsevier Inc. All rights reserved.
Flow Injection Amperometric Analysis of H2O2 at Platinum Nanoparticles Modified Pencil Graphite Electrode
(Wiley-V C H Verlag Gmbh, 2017) Karakaya, Serkan; Dilgin, Yusuf
A Pt nanoparticle modified Pencil Graphite Electrode (PGE) was proposed for the electrocatalytic oxidation and non-enzymatic determination of H2O2 in Flow Injection Analysis (FIA) system. Platinum nanoparticles (PtNPs) electrochemically deposited on pretreated PGE (p. PGE) surface by recording cyclic voltammograms of 1.0 mM of H2PtCl6 solution in 0.10 M KCl at scan rate of 50 mVs(-1) for 30 cycles. Cyclic voltammograms show that the oxidation peak potential of H2O2 shifts from about + 700 mVat bare PGE to + 50 mVat PtNPs/p.PGE vs. Ag/AgCl/ KCl (sat.). It can be concluded that PtNPs/p. PGE exhibits a good electrocatalytic activity towards oxidation of H2O2. Then, FI amperometric analysis of H-2 O-2 was performed under optimized conditions using a new homemade electrochemical flow cell which was constructed for PGE. Linear range was found as 2.5 mu M to 750.0 mMH(2)O(2) with a detection limit of 0.73 mu M (based on Sb/m of 3). As a result, this study shows the first study on the FI amperometric determination of H2O2 at PtNPs/p. PGE which exhibits a simple, low cost, commercially available, disposable sensor for H2O2 detection. The proposed electrode was successfully applied to determination of H2O2 in real sample.
Flow-Injection Amperometric Determination of Glucose Using Nickel Oxide-Cobalt (II,III) Oxide and Nickel Oxide-Copper Nanoparticle Modified Pencil Graphite Electrodes
(Taylor & Francis Inc, 2022) Ayaz, Selen; Karakaya, Serkan; Emir, Gamze; Usakligil, Nihan; Dilgin, Didem Giray; Dilgin, Yusuf
This study features an enzyme-free amperometric determination of glucose with flow injection analysis (FIA) using pencil graphite electrodes (PGEs) modified with nickel oxide-cobalt (II,III) oxide (NiO-Co3O4/PGE) and nickel oxide-copper nanoparticle (NiO-CuNPs/PGE). Both modified PGEs exhibited excellent electrocatalytic activity toward oxidation of glucose in strong alkaline media since they enhanced the peak current compared with the bare PGE and single metal oxide- or metal nanoparticle-modified PGEs. Flow-injection (FI) amperometry showed the linear response range, the limit of detection and sensitivity for NiO-Co3O4/PGE and NiO-CuNPs/PGE were 1.0-1000 mu M, 0.23 mu M and 586 mu A mM(-1) cm(-2), and 0.10-250 mu M, 0.03 mu M and 949 mu A mM(-1) cm(-2), respectively. Glucose was determined in real samples with good accuracy and precision.
Highly Sensitive Square Wave Voltammetric Determination of Sunset Yellow at a functionalized-MWCNTs/poly(Alizarin Red-S) Composite Modified Electrode
(Wiley-V C H Verlag Gmbh, 2022) Gunes, Mehmet; Karakaya, Serkan; Dilgin, Yusuf
This work presents an effective and highly sensitive electrochemical detection of Sunset Yellow (SSY) at poly(Alizarin Red-S) and functionalized multi-walled carbon nanotubes composite modified glassy carbon electrode (f-MWCNTs/poly(ALR-S)/GCE). The electrochemical response of the f-MWCNTs/poly(ALR-S)/GCE towards SSY was examined by cyclic voltammetry (CV) and square wave voltammetry (SWV). Both recorded cyclic voltammograms (CVs) and square wave voltammograms (SWVs) showed that the oxidation/reduction peaks of SSY at f-MWCNTs/poly(ALR-S)/GCE were found to be much higher than the bare GCE, f-MWCNTs/GCE, and poly(ALR-S)/GCE. Calibration curves obtained from the SWVs indicated that the f-MWCNTs/poly(ALR-S)/GCE offers a linear response in the range of 0.50 to 256 mu M with a low detection limit (LOD) of 0.16 mu M and the sensitivity was found to be 9686 mu A mM(-1) cm(-2). The f-MWCNTs/poly(ALR-S)/GCE provides excellent performance for the detection of SSY in daily life samples with high accuracy and precision.
Low Cost, Sensitive and Selective Chronoamperometric Determination of Vanillin at a Disposable Poly(Eriochrome Black T)/Pencil Graphite Electrode
(Sidas Medya A.S., 2020) Karakaya, Serkan
In this study, low cost, sensitive and selective chronoamperometric determination of vanillin (VNL) is firstly achieved by using a disposable poly(Eriochrome Black T) modified pencil graphite electrode (poly(EBT)/PGE). Electro-oxidation behavior of 1.0 mM VNL was investigated at both poly(EBT)/PGE and PGE by the cyclic voltammetry (CV) method. CV measurements showed that oxidation current of VNL at poly (EBT)/PGE was much higher than the bare one. Furthermore, the pH effect on electro-oxidation current of VNL was tested at different pH values (2.0-8.0) of Britton Robinson Buffer solution (BRBS) for poly(EBT)/PGE and the highest current was obtained at pH 7.0 BRBS. Significant analytical parameters such as linear response range (LRR), limit of detection (LOD), and sensitivity were found as 0.050-10.0 µM, 0.013 µM and 5355 µA mM-1 cm-2, respectively. The fabricated sensor was tested on a VNL-containing sample (VNL content: 3.0%) and the result (3.04% ±0.01) obtained from the applicability study showed that the proposed sensor enables the determination of VNL with high accuracy and precision. © 2020 Authors. All rights reserved.
Low-cost determination of cetirizine by square wave voltammetry in a disposable electrode
(Springer Wien, 2019) Karakaya, Serkan; Dilgin, Didem Giray
In the present study, an antihistamine drug, cetirizine hydrochloride (CTZN), was determined using square wave voltammetry and cyclic voltammetry based on its oxidation in a disposable and unmodified/bare graphite pencil electrode. To see the electrochemical behavior of CTZN, cyclic voltammograms of 0.10 mM CTZN in various types of carbon-based electrodes such as glassy carbon electrode (GCE), carbon paste electrode, multi-walled carbon nanotube (MWCNT) modified GCE, graphite pencil(GP), and pretreated graphite pencil (p.GP) were recorded in pH 3.0 Britton Robinson Buffer (BRB) solution. The result showed that CTZN is irreversibly oxidized at around + 1.0 V in all electrodes and among the studied electrodes p.GP showed the highest oxidation current for CTZN. Thus, the effect of pH on the electrochemical response of CTZN was investigated at the p.GP electrode by recording cyclic voltammograms of 0.10 mM CTZN in the BRB solutions in which pH was ranging from 2.0 to 10.0. The highest oxidation current of CTZN was observed at pH 2.0 BRB solution. Under the optimized SW voltammetric conditions, a linear response for the determination of CTZN was obtained in the range from 0.50 to 10.0 mu M CTZN with a detection limit (LOD) of 0.16 mu M. Applicability of the proposed sensor was also tested for determination of CTZN in antihistamine syrup (Zyrtec). Results of the measurements indicated that p.GP can be successfully used for CTZN detection in real samples.
Metal nanoparçacık modifiye kalem grafit elektrot kullanılarak akışa enjeksiyon analizde sensör ve biyosensör uygulamaları
(Çanakkale Onsekiz Mart Üniversitesi, Lisansüstü Eğitim Enstitüsü, 2019) Karakaya, Serkan; Dilgin, Yusuf
Bu tez çalışmasında, (i) yüksek iletkenlik özelliğine ve katalitik etkinliğe sahip metal nanoparçacıklar (Au, Pt ve Pd), (ii) ucuz ve tek kullanımlık kalem grafit elektrot (pencil graphite electrode, PGE), (iii) hızlı ve rutin analizlere olanak sağlayan akışa enjeksiyon analiz (Flow Injection Analysis, FIA) metodu gibi üç faydalı bileşen üzerinden elektrokimyasal sensör ve biyosensör çalışmaları gerçekleştirilmiştir. Bu amaçla Au, Pt, Pd ve Pt-Pd nanoparçacıklar PGE yüzeyine elektrokimyasal olarak biriktirilmiş ve elde edilen elektrotların H2O2'ye yanıtı döngüsel voltammetri (CV) tekniği ile incelenmiştir. Elektrokimyasal H2O2 sensörü, sırasıyla Au ve Pt ile Pd ve Pt-Pd modifiye PGE'lerde H2O2'nin yükseltgenmesi ve indirgenmesi üzerine geliştirilmiştir. Her bir modifiye elektrot için çalışma potansiyeli ve akış hızı optimize edilmiş ve FIA sisteminde amperometrik H2O2 sensörünün analitiksel parametreleri belirlenmiş ve gerçek örneklere uygulanabilirlikleri başarıyla test edilmiştir. Tezin ikinci kısmında ise metal/bimetal nanoparçacık modifiye PGE'ler yüzeyine glukoz oksidaz (GOx) immobilize edilmiş ve glukoz biyosensör çalışmaları CV tekniğiyle gerçekleştirilmiştir. Glukoza en iyi elektrokatalitik etkinliğin ve yanıtın alındığı elektrotlar GOx immobilize Pt ve Pt-Pd modifiye PGE'ler olarak belirlenmiştir. Her iki elektrot için FIA sisteminde geliştirilen amperometrik glukoz biyosensörünün optimize edilen koşullar altında analitiksel performansları belirlenmiş ve gerçek örneklere uygulanabilirlikleri başarıyla test edilmiştir. Askorbik asit, dopamin ve ürik asitin geliştirilen glukoz biyosensörüne girişim etkileri, NaBiO3 önyükseltgeyicisi kullanılarak önemli derecede giderilmiştir. Sonuç olarak, metal/bimetal nanoparçacık, PGE ve FIA sistemi bir arada kullanılarak ucuz, hızlı, duyarlı elektrokimyasal sensör ve biyosensör tasarlanması, girişimcilerin giderilmesinde FIA'da NaBiO3 ön yükseltgeyicisinin ilk defa kullanılması bu çalışmanın özgün kısmını oluşturmaktadır. Anahtar sözcükler: Elektrokimyasal Sensör/Biyosensör, Akışa Enjeksiyon Analizi, Glukoz Oksidaz, Sodyum Bizmutat, Metal Nanoparçacık, Kalem Grafit Elektrot.
Minimization of Interferences in Flow Injection Amperometric Glucose Biosensor Based on Oxidation of Enzymatically-produced H2O2
(Wiley-V C H Verlag Gmbh, 2019) Karakaya, Serkan; Dilgin, Yusuf
One of the major problems in amperometric biosensors based on detection of H2O2 produced by enzymatic reaction between oxidase enzymes and substrate is the interference of redox active compounds such as ascorbic acid (AA), dopamine (DA) and uric acid (UA). To minimize these interferences, sodium bismuthate was used for the first time as an insoluble pre-oxidant in the flow injection (FI) amperometric glucose biosensor at a Glucose oxidase (GOx) immobilized Pt/Pd bimetallic modified pre-anodized pencil graphite electrode (p.PGE). In this context, these interfering compounds were injected into a flow injection analysis (FIA) system using an injector which was filled with NaBiO3. Thus, these interferents were converted into their redox inactive oxidized forms before reaching the electrode in the flow cell. While glucose was not influenced by the pre-oxidant in the injector, the huge oxidation peak currents of the interferents decreased significantly in the biosensor. FI amperometric current time curves showed that the AA, DA and UA were minimized by 96 %, 86 %, and 98 % respectively, in the presence of an equivalent concentration of interferences in a 1.0 mM glucose solution. The proposed FI amperometric glucose biosensor exhibits a wide linear range (0.01-10 mM, R-2=0.9994) with a detection limit of 2.4x10(-3) mM. Glucose levels in the artificial serum and two real samples were successfully determined using the fabricated FI amperometric biosensor.
Pyrocatechol Violet Modified Graphite Pencil Electrode for Flow Injection Amperometric Determination of Sulfide
(Korean Electrochemistry Soc, 2020) Emir, Gamze; Karakaya, Serkan; Dilgin, Yusuf
In this study, pyrocatechol violet (Pcv) is proposed for the first time as an efficient electrocatalyst for oxidation of sulfide and flow injection analysis (FIA) of sulfide. A graphite pencil electrode (GPE) was modified with Pcv via immersion of the GPE into 0.01 M Pcv solution for 15 min. Cyclic voltammograms (CVs) demonstrated that Pcv/GPE exhibits a good electrocatalytic performance due to shift in the potential from +400 at bare GPE to +70 mV at Pcv/GPE and obtaining an enhancement in the peak current compared with the bare GPE. A linear range between 0.25 and 250 mu M sulfide with a detection limit of 0.07 mu M was obtained from the recorded current-time curves in Flow Injection Analysis (FIA) of sulfide. Sulfide in water samples was also successfully determined using the proposed FI amperometric methods.

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