Browsing by Author "Selcuk, Kadir"

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Electrochemical Cysteine Sensor on Novel Ruthenium Based Ternary Catalyst
(Esg, 2021) Kivrak, Hilal; Selcuk, Kadir; Er, Omer Faruk; Aktas, Nahit
At present, a voltammetric L-Cystein (Cys) sensor is developed based on carbon nanotube (CNT) supported Ru-Mo-Pd trimetallic catalyst modified glassy carbon electrodes (GCE). Firstly, Ru-Mo/CNT catalysts are prepared via sodium borohydride reduction method and following this Ru-Mo/CNT modified GCE electrode is prepared and Pd electrodeposition at varying Pd concentrations is performed to obtain Ru-Mo-Pd/CNT catalysts. Ru-Mo-Pd/CNT catalyst is characterized by TEM and SEM-EDX. Characterization results reveal that Ru-Mo-Pd/CNT catalyst is succesfully synthesized. For electrochemical measurements, GCE is modified with Ru-Mo-Pd/CNT catalysts and electrochemical behavior of the modified GCE is investigated by cyclic voltammetry, differential pulse voltammetry, electrochemical impedance spectroscopy. Ru-Mo-Pd/CNT at 0.0152 mM Pd concentration modified GCE electrode have the best Cys electrooxidation activity. Hence, further electrochemical measurements to determine sensitivity, limit of detection, intereference study, and real sample are performed on Ru-Mo-Pd/CNT at 0.0152 mM Pd concentration modified GCE electrode. This sensor has a wide linear response within the range of 5-200.M with high current sensitivity 0.136.A/.M and 0.1.M as lowest detection limit at (S/N=3) signal to noise ratio. Interference studies reveal that Ru-Mo-Pd/CNT sensor is not affected by common interfering species. This novel study reports a strategy to sense Cys on Ru/CNT modified GCE electrode.
Nanostructured Electrochemical Cysteine Sensor Based on Carbon Nanotube Supported Ru, Pd, and Pt Catalysts
(Elsevier Science Sa, 2021) Kivrak, Hilal; Selcuk, Kadir; Er, Omer Faruk; Aktas, Nahit
At present, a voltammetric L-Cystein (Cys) sensor is developed based on carbon nanotube (MWCNT) supported Ru, Pd, and Pt monometallic catalyst modified glassy carbon electrodes (GCE). Ru/MWCNT, Pd/MWCNT, and Pt/MWCNT catalysts are prepared via sodium borohydride reduction method and characterized with advanced surface analytical techniques as inductively coupled plasma mass spectrometry (ICP-MS), N2 adsorptiondesorption, X-ray diffraction (XRD), and transission electron microscopy (TEM). Characterization results reveal that these catalysts are succesfully sythesized at desired metal loadings. For electrochemical studies, GCE is modified with Ru/MWCNT, Pd/MWCNT, and Pt/MWCNT catalysts to obtain a disposable, inexpensive, and sensitive sensor for Cys. The electrochemical behavior of the modified GCE is investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). Ru/MWCNT modified GCE electrode exhibits best Cys electro-oxidation activity and thus, further electrochemical studies as sensitivity and limit of detection determination, intereference study, and real sample analysis are performed on Ru/MWCNT modified GCE electrode. The Cys sensor has a linear response within the range of 0-200 mu M with current sensitivity 0.3058 mu A/mu M (4307.05 mu A/mMcm2), and 0.353 lowest detection limit at (S/N = 3) signal to noise ratio. Interference studies reveal that Ru/MWCNT modified GCE electrode is not affected by D-glucose, uric acid, L-Tyrosine, L-Trytophane, H2O2, homocysteine, and glutathione as common interfering species. The
Novel Cnt Supported Molybdenum Catalyst for Detection of L-Cysteine in Its Natural Environment
(Mdpi, 2021) Selcuk, Kadir; Kivrak, Hilal; Aktas, Nahit
In this study, novel carbon nanotube-supported Mo (Mo/CNT) catalysts were prepared with the sodium borohydride reduction method for the detection of L-cysteine (L-Cys, L-C). Mo/CNT catalysts were characterized with scanning electron microscopy with elemental dispersion X-ray (EDX-SEM), X-ray diffraction (XRD), UV-vis diffuse reflectance spectrometry (UV-vis), temperature-programmed reduction (TPR), temperature programmed oxidation (TPO), and temperature-programmed desorption (TPD) techniques. The results of these advanced surface characterization techniques revealed that the catalysts were prepared successfully. Electrochemical measurements were employed to construct a voltammetric L-C sensor based on Mo/CNT catalyst by voltammetric techniques such as cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Further measurements were carried out with electrochemical impedance spectroscopy (EIS). Mo/CNT/GCE exhibited excellent performance for L-C detection with a linear response in the range of 0-150 mu M, with a current sensitivity of 200 mA/mu M cm(2) (0.0142 mu A/mu M), the lowest detection limit of 0.25 mu M, and signal-to-noise ratio (S/N = 3). Interference studies showed that the Mo/CNT/GCE electrode was not affected by D-glucose, uric acid, L-tyrosine, and L-trytophane, commonly interfering organic structures. Natural sample analysis was also accomplished with acetyl L-C. Mo/CNT catalyst is a promising material as a sensor for L-C detection.
Novel Gallium-Based Voltammetric Sensor for Sensitive Detection of Cysteine
(Pergamon-elsevier Science Ltd, 2022) Selcuk, Kadir; Caglar, Aykut; Aktas, Nahit; Kivrak, Hilal
Carbon nanotube-supported gallium (Ga/CNT) was synthesized and characterized with energy dispersive X-ray scanning electron microscopy, temperature-programmed reduction, temperature-programmed oxidation, and temperature-programmed desorption methods. Characterization results revealed successful preparation of Ga/ CNT. Electrochemical measurements were performed by cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy. The Ga/CNT-based cysteine sensor had a linear response within the range of 0-200 mu M with current sensitivity of 0.0081 mu A/mu M (114 mu A/mM cm(2)), low detection limit of 0.05 mu M, and signal-to-noise ratio of 3. Interference studies revealed that (Ga/CNT)@glassy carbon electrode was not affected by interfering species. Thus, Ga/CNT is a promising cysteine sensor.
The Preparation, Characterization, and Electrooxidation of Colloidal Palladium Modified Poly(Methacrylic Acid) Hydrogel as Formic Acid Fuel Cell Anode Catalyst
(Wiley, 2022) Kivrak, Hilal; Khalid, Sarwar; Caglar, Aykut; Alpaslan, Duygu; Selcuk, Kadir; Dudu, Tuba Ersen; Aktas, Nahit
At present, poly(methacrylic acid) (MA), poly(MA) hydrogel, and Pd-doped poly(MA) hydrogel modified electrodes are constructed on graphite pencil (G). The Pd precursor is coated on the poly(MA)/G electrodes surface using the electrodeposition method. These electrodes are characterized by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy, and scanning electron microscopy-energy dispersive X-ray. Poly(MA) hydrogel and Pd-doped poly(MA) hydrogel are successfully prepared by the polymerization and further electrodeposition. Formic acid electro-oxidation (FAEO) activities are examined with cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS). Poly(MA)/G and Pd doped poly(MA) electrodes exhibit promising electro-catalytic activity with 60 mA current density, greater than literature values. Pd-doped poly(MA) hydrogel electrodes are promising electrodes for FAEO.
Selective Electrochemical Determination of L-Cysteine by a Cobalt Carbon Nanotube (cnt)-Modified Glassy Carbon Electrode (Gce)
(Taylor & Francis inc, 2024) Kivrak, Hilal; Selcuk, Kadir; Caglar, Aykut; Aktas, Nahit
L-Cysteine is a semi-essential and proteinogenic amino acid, with the formula HO2CCH (NH2) CH2SH. L-cysteine is mostly found in protein-rich foods. In this study, catalysts consisting of cobalt (Co) supported on carbon nanotubes (CNTs) were prepared using the sodium borohydride (NaBH4) reduction method. These catalysts were characterized by means of energy-dispersive x-ray (EDX) with scanning electron microscopy (SEM), temperature-programmed reduction (TPR), and temperature-programmed oxidation (TPO) techniques. Characterization results confirmed the successful preparation of the desired catalyst. After preparing the Co/CNT catalysts, a highly efficient and sensitive electrochemical sensor was developed using a glassy carbon electrode (GCE) modified with the Co/CNT catalysts. The electrochemical behavior of the bare GCE and Co/CNT-modified GCE electrodes was investigated using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS) in 0.1 M phosphate buffer solution (PBS) + L-cysteine. Electrochemical results showed that the Co/CNT-modified GCE electrode exhibited high sensitivity and selectivity compared to the bare GCE, with sensitivity of 0.0046 mu A/mu M, limit of detection of 0.2 mu M, and limit of quantification of 0.6 mu M. Furthermore, this electrode showed higher sensitivity values than those reported in the literature. Further interference studies were performed using CV and EIS to investigate interfering species in the serum environment, such as D-glucose, uric acid, L-tyrosine, and L-tryptophan. In conclusion, the results suggest that the Co/CNT-modified GCE electrode is a promising catalyst for the sensitive detection of L-cysteine.