Browsing by Author "Er, Omer Faruk"

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A Comprehensive Study of Hydrogen Production From Ammonia Borane Via Pdcoag/Ac Nanoparticles and Anodic Current in Alkaline Medium: Experimental Design With Response Surface Methodology
(Higher Education Press, 2020) Celik Kazici, Hilal; Yilmaz, Sakir; Sahan, Tekin; Yildiz, Fikret; Er, Omer Faruk; Kivrak, Hilal
In this paper, the optimization of hydrogen (H-2) production by ammonia borane (NH3BH3) over PdCoAg/AC was investigated using the response surface methodology. Besides, the electro-oxidation of NH3BH3 was determined and optimized using the same method to measure its potential use in the direct ammonium boran fuel cells. Moreover, the ternary alloyed catalyst was synthesized using the chemical reduction method. The synergistic effect between Pd, Co and Ag plays an important role in enhancement of NH3BH3 hydrolysis. In addition, the support effect could also efficiently improve the catalytic performance. Furthermore, the effects of NH3BH3 concentration (0.1-50 mmol/5 mL), catalyst amount (1-30 mg) and temperature (20 degrees C-50 degrees C) on the rate of H-2 production and the effects of temperature (20 degrees C-50 degrees C), NH3BH3 concentration (0.05-1 mol/L) and catalyst amount (0.5-5 mu L) on the electro-oxidation reaction of NH3BH3 were investigated using the central composite design experimental design. The implementation of the response surface methodology resulted in the formulation of four models out of which the quadratic model was adjudged to efficiently appropriate the experimental data. A further statistical analysis of the quadratic model demonstrated the significance of the model with a p-value far less than 0.05 for each model and coefficient of determination (R-2) of 0.85 and 0.95 for H-2 production rate and NH3BH3 electrroxidation peak current, respectively.
Design of 2-(4 Based Remarkable Organic Catalyst Towards Hydrazine Electrooxidation
(Elsevier Science Sa, 2021) Er, Omer Faruk; Ulas, Berdan; Ozok, Omruye; Kivrak, Arif; Kivrak, Hilal
Herein, 2-(4-(2-pentyllbenzo[ b]thiophen-3-yl)benzylidene)malononitrile (6B) is synthesized by using coupling reactions, electrophilic cyclization reactions, and condensation reactions. Then, these materials are employed as anode catalysts for hydrazine electrooxidation reactions with electrochemical methods such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in 1 M KOH + 0.5 M N2H4 solution on different benzothiophene derivates. 6B catalyst exhibits the best catalytic activity in hydrazine electrooxidation reaction with 3.22 mA cm(-2) (16.72 mA mg(-1) 6B) value. Thus, for the electrodes obtained from 6B, the electrode preparation stage is optimized by the response surface methodology (RSM) and the hydrazine electrooxidation current under optimum conditions is found as 4.95 mA cm(-2). EIS results reveal that 6B modified electrode has the lowest charge transfer resistance. In conclusion, 6B catalyst could be used as anode catalysts in hydrazine fuel cells instead of expensive catalysts such as Pt, Pd, and Au.
Disentangling the Enhanced Catalytic Activity on Ga Modified Ru Surfaces for Sodium Borohydride Electrooxidation
(Elsevier, 2021) Ulas, Berdan; Alpaslan, Duygu; Yilmaz, Yonca; Dudu, Tuba Ersen; Er, Omer Faruk; Kivrak, Hilal
Herein, multi walled carbon nanotube (MWCNT) supported RuGa nanocatalysts (RuGa/MWCNTs) are synthesized at varying atomic molar ratio via sodium borohydride (SBH) reduction method toward SBH electrooxidation (SBHE) and SBH hydrolysis (RSBH). From the X-ray diffraction (XRD) results, Ru and Ga metals are found to be in the alloy form and the average crystal size is determined as 2.77 nm. The distribution of RuGa particles on MWCNT is confirmed using SEM-EDX. These nanocatalysts were employed for RSBH and further measurements were performed to investigate their SBHE activity. For RSBH for RuGa/MWCNT nanocatalysts, one could note that Ga addition to Ru enhanced the initial rate, H-2 generation rate, and turnover frequency values and Ru99Ga1/MWCNT has the highest initial rate, H-2 generation rate, and turnover frequency value. According to the cyclic voltammetry (CV) results of the prepared RuGa/MWCNT nanocatalysts, Ru99Ga1/ MWCNT show the highest electrocatalytic activity for SBHE and this result is in line with the results of electrochemical impedance spectroscopy (EIS). In addition, chronoamperometric curves indicate that Ru99Ga1/MWCNT possesses long term stability compared to these of other nanocatalysts. Catalytic RSBH results of Ru99Ga1/MWCNT show that this nanocatalyst is more active than others. As a result, it is clear that RuGa/ MWCNT is a promising nanocatalyst for fuel cells.
The Effect of Different Carbon-Based Cdte Alloys for Efficient Photocatalytic Glucose Electrooxidation
(Elsevier Science Sa, 2022) Caglar, Aykut; Er, Omer Faruk; Aktas, Nahit; Kivrak, Hilal
The activated carbon (AC), graphene (G), reduced graphene oxide (rGO), carbon nanotube (CNT) supported CdTe photocatalysts at (50-50) atomic molar are synthesized by the sodium borohydride (SBH) method and characterized by the XRD, Micro-Raman, TEM-EDS, XPS, and TPx (TPR, TPO, and TPD) analyses. The CV, CA, and EIS electrochemical analyses are performed to investigate the catalytic activities of catalysts for photocatalytic glucose electrooxidation. Characterization analyses reveal that their electronic structures and surface properties change when carbon materials are doped with metal. The photocatalytic glucose electrooxidation results indicate that the 0.1 % CdTe(50-50)/CNT catalyst exhibited better photocatalytic activity, stability, and resistance than other catalysts both at dark (1.9 mA/cm2) and under UV illumination (2.57 mA/cm2). Therefore, the CNT-supported CdTe catalyst can be said a promising catalyst for direct glucose fuel cells.
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.
Enhanced Electrochemical Glucose Oxidation in Alkaline Solution Over Indium Decorated Carbon Supported Palladium Nanoparticles
(Elsevier Science Sa, 2020) Er, Omer Faruk; Caglar, Aykut; Kivrak, Hilal
At present, carbon nanotube (CNT) supported In modified Pd catalysts are prepared at varying Pd:In ratios via NaBH4 reduction method to investigate the synergetic effect of Pd and In monometallic catalysts through glucose electrooxidation. These catalysts are characterized by advanced surface analytical techniques, namely, inductively coupled plasma-mass spectrometry (ICP-MS) with Agilent 7800 ICP-MS, N-2 adsorption-desorption measurements (BET) with Micromeritics 3Flex equipment Tristar II 3020 equipped, PANalytical Empyrean device-ray diffractometer (XRD), Hitachi HighTech HT7700 high resolution-transmission electron microscope (HR-TEM), and scanning electron microscope (SEM). Electrochemical measurements are performed by using cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) by CHI660E potentiostat in a three electrode system. The characterization results show that all catalysts are successfully synthesized at desired molar composition. For PdIn (90:10)/CNT catalyst, the crystal size obtained from HR-TEM is 2.36 nm and BET surface area is 212.28 cm(2)g(-1).5% PdIn(90:10)/CNT catalyst exhibits the best catalytic activity, lowest charge transfer resistance (Rct), and a long term stability compared to Pd, In, other Pd:In bimetallic catalysts. EIS and CA results are in a good agreement with CV results.
Glucose Electrooxidation Modelling Studies on Carbon Nanotube Supported Pd Catalyst With Response Surface Methodology and Density Functional Theory
(Pergamon-elsevier Science Ltd, 2022) Kaya, Sefika; Ulas, Berdan; Duzenli, Derya; Onal, Isik; Er, Omer Faruk; Yilmaz, Yonca; Kivrak, Hilal
In this study, carbon nanotube supported Pd catalysts (Pd/CNT) are synthesized at different weight percentages by the sodium borohydride (NaBH4) reduction method to investigate catalytic performance of glucose electrooxidation reaction. 0.5% Pd/CNT, 3% Pd/CNT, and 7% Pd/CNT catalysts are characterized by using X-ray diffraction (XRD), electron microscopy with energy dispersive X-ray (SEM-EDX), and N2 adsorption-desorption measurements. The average particle size and surface area of 3% Pd/CNT catalyst are determined as 46.33 nm and 129.48 m2/g, respectively. Characterization results indicate that Pd/CNT catalysts are successfully prepared by NaBH4 reduction method. Cyclic voltammetry measurements are performed to investigate the effect of Pd loading for the glucose electrooxidation. CV results reveal that 3% Pd/CNT catalyst exhibits best glucose electrooxidation activity. Following this, experimental optimization is performed to obtain maximum glucose electrooxidation activity via response surface methodology (RSM). Estimated and experimental specific activities at optimum experimental conditions are assigned as 6.186 and 5.832 mA/cm2, respectively. To understand the glucose electrooxidation activity on the surface of Pd/CNT, surface modeling is also performed with density functional theory (DFT) method to investigate adsorption of glucose molecule on CNT supported Pd surface. The DFT results emphasize that the addition of Pd atom to the CNT structure significantly improves the catalytic performance in glucose electrooxidation.
Highly Active Carbon Nanotube Supported Iridium, Copper, Ruthenium Catalysts for Glucose Electrooxidation
(Wiley, 2021) Er, Omer Faruk; Kivrak, Hilal
Herein, carbon nanotube (CNT) supported ruthenium (Ru), iridium (Ir), and copper (Cu) catalysts at 0.1 to 20 wt% metal loading are prepared by the NaBH4 reduction method for glucose electrooxidation reaction (GER). These catalysts are successfully characterized by X-ray diffraction, scanning electron microscope, and N-2 adsorption-desorption measurements. Voltammetric measurements of these catalysts are taken using cyclic voltammetry and chronoamperometry techniques. The crystallite sizes of these catalysts are calculated as 2.53 nm for Ru/CNT, 2.94 nm for Ir/CNT, and 13.06 nm for Cu/CNT by using Scherrer equation. For GER, 10% Ru/CNT, 0.1% Ir/CNT, and 0.5% Cu/CNT catalysts have high current densities as 1.86 mA cm(-2) (160.6 mA mg(-1) Ru), 3.03 mA cm(-2) (23 857.2 mA mg(-1) Ir), and 1.12 mA cm(-2) (1768.8 mA mg(-1) Cu), respectively. These catalysts have also good stability. Results reveal that 10% Ru/CNT, 0.1% Ir/CNT, and 0.5% Cu/CNT catalysts are promising catalysts as direct glucose fuel cell anode catalysts.
Highly Active Rupd Bimetallic Catalysts for Sodium Borohydride Electrooxidation and Hydrolysis
(Springer, 2022) Kaya, Sefika; Yilmaz, Yonca; Er, Omer Faruk; Alpaslan, Duygu; Ulas, Berdan; Dudu, Tuba Ersen; Kivrak, Hilal
In the present study, bimetallic RuPd/carbon nanotube (RuPd/CNT) electrocatalysts were synthesized at different molar ratios by sodium borohydride (NaBH4) reduction. These catalysts were characterized with advanced surface characterization techniques such as x-ray diffraction (XRD), scanning electron microscopy with energy dispersive x-ray (SEM-EDX), and x-ray photoelectron spectroscopy (XPS). The activities of these catalysts towards electrooxidation of NaBH4 and hydrogen production from hydrolysis/methanolysis of NaBH4 were investigated. According to XRD results, the particle sizes of Ru/CNT and Ru60Pd40/CNT catalysts were calculated as 3.16 and 3.05 nm, respectively. The distribution and elemental composition of Ru and Pd nanoparticles on CNT were obtained by SEM-EDX analysis. The XPS method was used to determine the oxidation states of Ru and Pd on the CNT surface. The electrochemical activities of these catalysts were determined by cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) measurements. The results show that the Ru60Pd40/CNT catalyst has the highest current mass activity with 2161.94 mA/mg Ru (12.72 mA/cm(2)) current density. Consequently, the RuPd/CNT catalyst is a promising anode catalyst for direct borohydride fuel cells (DBFC) with good stability and high activity.
Hydrazine Electrooxidation Activities of Novel Carbon Nanotube Supported Tin Modified Palladium Nanocatalysts
(Elsevier, 2022) Er, Omer Faruk; Cavak, Ali; Aldemir, Adnan; Kivrak, Hilal
At present, monometallic Sn/MWCNT nanocatalyst and bimetallic PdSn/MWCNT nanocatalysts are synthesized by the NaBH4 reduction method to investigate their activities in hydrazine electrooxidation (HEO) reaction. 5% Pd80Sn20/MWCNT nanocatalysts are characterized via N-2 adsorption desorption, X-ray diffractometer (XRD), and transmission electron microscopy (TEM). Electrochemical activities and charge transfer resistances (Rct) of all prepared nanocatalysts are studied via cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Results reveal that Sn addition to Pd improves HEO activities. In addition, 5% Pd80Sn20/MWCNT nanocatalyst shows the highest activity with 13.70 mA cm(-2) (4029.58 mA mg(-1) PdSn) current density value in HEO. Furthermore, 5% Pd80Sn20/MWCNT nanocatalyst displays the lowest charge transfer resistance. Results reveal PdSn/MWCNT nanocatalysts with high current values than literature reported values are promising nanocatalysts for hydrazine fuel cells.
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 5-(2 [B] Thiophen-3 Based Ovarian Cancer Carbohydrate Antigen 125 Electrochemical Sensor
(Elsevier Science Sa, 2022) Er, Omer Faruk; Kivrak, Hilal; Ozok, Omruye; Kivrak, Arif
Herein, an electrochemical sensor based 5-(2-phenylbenzo [b] thiophen-3-yl)furan-2-carbaldehyde (PTFC) was developed for the detection of cancer antigen 125 (CA125). Measurements were obtained via cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV), and square wave voltammetry (SWV) techniques to investigate features of the electrochemical sensor such as concentration effect of CA125, incubation time, scan rate, limit of quantification (LOQ), limit of detection (LOD), and interference effect of structures found in serum. The sensor was found to have a fairly wide linear range as 0.01-100 ng mL(-1) and 100-1000 ng mL(-1). LOQ and LOD values were determined as 0.024015 ng mL(-1) and 0.008005 ng mL(-1) (S/N = 3), respectively. These results showed that the PTFC-based electrode could be a promising electrode for the detection of CA125.
Novel Benzothiophene Based Catalyst With Enhanced Activity for Glucose Electrooxidation
(Pergamon-elsevier Science Ltd, 2020) Ozok, Omruye; Kavak, Emrah; Er, Omer Faruk; Kivrak, Hilal; Kivrak, Arif
Thiophene based heterocyclic compounds plays important roles in organic chemistry due to their unexpected properties. Herein, novel benzothiophene derivatives (6A-F) are synthesized via Sonogashira coupling, iodocyclization reaction, Suzuki-Miyaura coupling and condensation reactions. After characterization of design molecules, their glucose electrooxidation activities are investigated. Electrochemical measurements are performed by cyclic voltammetry, chrono amperometry, and electrochemical impedance spectroscopy in 1 M KOH +0.5 M C6H12O6 solution. This results show that the highest performance organic-based catalysts is obtained as 0.729 mA/cm(2) (3.345 mA/mg) for the 2-(4-(2-pentylbenzo [b] thiophen-3-yl)benzylidene)malononitrile (6B). Furthermore, 6B catalyst is shown long term stability, the best current density value (1.151 mA cm(-2)), and the best transfer resistance load between organic-based catalysts. As a result, it is clear that these benzothiophene derivatives are promising organic based catalyst, an alternative to the expensive Pd and Pt based metal catalyst, for direct glucose fuel cell anode. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
Novel Cacao Oil-Based Organo-Hydrogels To Detect Carcinoma Antigen 125 in Serum Medium; Synthesis, Characterization, and Electrochemical Measurements
(Elsevier Science Sa, 2022) Er, Omer Faruk; Alpaslan, Duygu; Dudu, Tuba Ersen; Aktas, Nahit; Kivrak, Hilal
In present study, cacao oil-based organo-hydrogels (OHCOs) are synthesized to detect carcinoma antigen 125 (CA-125) in serum medium with electrochemical methods such as cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV). OHCOs are prepared by the free radical polymerization reaction with agar, glycerol, and distinct ratios of cacao oil with glutaraldehyde (GA) crosslinker or methylene bisacrylamide (MBA) crosslinker. OHCOs are characterized via Fourier Transform Infrared Spec-troscopy (FT-IR), in different solvent environments and pHs. Electrochemical measurements are performed on OHCOs at the presence and absence of CA-125 antigen in serum medium. For the electrochemical sensor, two distinct linear ranges are determined as 0.00083-41.5 U/mL and 83.0-2075 U/mL. LOD and LOQ values are found as 0.34 mu U/mL and 1.01 mu U/mL, respectively. These results clearly show that OHCOs is a promising sensor material for the determination of CA-125 in human serum, sensitively.
A Novel Carbohydrate Antigen 125 Electrochemical Sensor Based on Sweet Almond Oil Organo-Hydrogels
(Elsevier Science Sa, 2023) Er, Omer Faruk; Alpaslan, Duygu; Dudu, Tuba Ersen; Aktas, Nahit; Celik, Sebahattin; Kivrak, Hilal
Ovarian cancer is a gynecological disease causing many deaths among women around the world. Carbohydrate antigen 125 (CA-125) is a single biomarker known to be a tumor marker of ovarian cancer. CA-125 is widely used to monitor the treatment process, recurrences, and for the detection of ovarian cancer. Herein, organo-hydrogels were prepared in order to detect CA-125 sensitively in serum medium with electrochemical methods. Organo-hydrogels were obtained by the free radical polymerization reaction using agar and glycerol with varying pro-portions of sweet almond oil using methylene bisacrylamide (MBA) or glutaraldehyde (GA) crosslinkers. Elec-trochemical measurements were performed with cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV) on organo-hydrogel sweet almond oil (OHSAO) prepared in the presence and absence of CA-125. As a result of these measurements, two distinct linear ranges of 1-50 ng/mL and 100-1000 ng/mL were obtained. In addition, LOD and LOQ values for the sensor were calculated as 0.41 mu U/mL and 1.24 mu U/mL, respectively. In conclusion, the OHSAO-based electrochemical sensor is a promising electrode for CA-125 detection.
Novel Carbon Nanotube Supported Co@ag@pd Formic Acid Electrooxidation Catalysts Prepared Via Sodium Borohydride Sequential Reduction Method
(Elsevier Science Sa, 2020) Er, Omer Faruk; Caglar, Aykut; Ulas, Berdan; Kivrak, Hilal; Kivrak, Arif
At present, monometallic Pd/CNT, bimetallic Pd50Ag50/CNT, Pd50Co50/CNT, Ag50Pd50/CNT catalysts are prepared by NaBH4 co-reduction method. Ag@Pd/CNT catalysts at varying Ag:Pd ratios and Co@Ag@Pd/CNT catalysts at varying Co:Ag:Pd atomic ratios are prepared via NaBH4 sequential reduction method. These catalysts are characterized with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The characterization results show that all catalysts are successfully synthesized at desired molar composition. Furthermore, Ag and Co addition change electronic state of catalyst. Formic acid electrooxidation measurements of these catalysts are performed by cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) to investigate the effect of Ag and Co addition through the formic acid electrooxidation activity. Considering the bimetallic catalysts, Ag-50@Pd-50/CNT exhibits better catalytic activity than the one of other bimetallic catalysts. It is clear that the addition of Ag to Pd improves electrocatalytic activity due to synergetic effects. Furthermore, Co-0.072@Ag-19(.98)@Pd-79(.98)/CNT has the best activity, lowest charge transfer resistance (Rct), and a long term stability. EIS and CA results are in a good agreement with CV results. Co-0.072@Ag-19.98@Pd79.98/CNT is a promising catalyst for Direct formic acid fuel cells.
A Novel Electrochemical Sensor for Monitoring Ovarian Cancer Tumor Protein Ca 125 on Benzothiophene Derivative Based Electrodes
(Elsevier Science Sa, 2022) Er, Omer Faruk; Kivrak, Hilal; Ozok, Omruye; Celik, Sebahattin; Kivrak, Arif
COVID-19 crisis affects ovarium cancer patients seriously. Thus, it is vital to diagnose ovarium cancer, one of the most common types of cancer diagnosed and the causes of death of women around the world, at early stages. Herein, 5-(2-phenylbenzo[b]thiophen-3-yl) thiophene-2-carbaldehyde (PTTC)-based sensor is designed to detect CA-125 more precisely and rapidly via electrochemical methods. PTTC, novel benzothiophene derivative, is synthesized by electrophilic cyclization reactions and Pd-catalyst coupling reactions. Then, PTTC is dispersed homogeneously in Nafion solution, and an ink is obtained. This ink is transferred onto the glassy carbon electrode and CA-125 is incubated on this electrode. Cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy measurements are employed to determine sensitivity and reliability of CA-125 on PTTC based GCE electrode. The effect of CA 125 concentration, incubation time, scan rate studies are performed by CV to determine the optimum conditions. Optimum conditions are found as 3 mu L PTTC loading, 5000 ng/mL CA125 antigen concentration and 30 min incubation time. Linear range of the PTTC based GCE electrode prepared at optimum conditions are obtained by DPV as 1-100 ng/ml.Limit of detection and limit of quantification values were obtained as 0.0096 ng/mL and 0.0288 ng/mL, respectively. Interference and artificial serum results reveal that this electrode is a promising electrode for CA125 antigen determination for the ovarium cancer. PTTC is a novel and unique material for the detection of ovarium cancer antigen CA-125 and promising for CA-125 antigen detection.
One-Step Electrochemical Sensing of Ca-125 Using Onion Oil-Based Novel Organohydrogels as the Matrices
(Amer Chemical Soc, 2024) Er, Omer Faruk; Kivrak, Hilal; Alpaslan, Duygu; Dudu, Tuba Ersen
To reduce the high mortality rates caused by ovarian cancer, creating high-sensitivity, quick, basic, and inexpensive methods for following cancer antigen 125 (CA-125) levels in blood tests is of extraordinary significance. CA-125 is known as the exclusive glycoprotein employed in clinical examinations to monitor and diagnose ovarian cancer and detect its relapses as a tumor marker. Elevated concentrations of this antigen are linked to the occurrence of ovarian cancer. Herein, we designed organohydrogels (ONOHs) for identifying the level of CA-125 antigen at fast and high sensitivity with electrochemical strategies in a serum medium. The ONOH structures are synthesized with glycerol, agar, and glutaraldehyde and at distinct ratios of onion oil, and then, the ONOHs are characterized with Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). Electrochemical measurements are performed by cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS) in the absence and presence of CA-125 on the designed ONOHs. For the prepared ONOH-3 electrode, two distinct linear ranges are determined as 0.41-8.3 and 8.3-249.0 U/mL. The limit of quantitation and limit of detection values are calculated as 2.415 and 0.805 mu U/mL, respectively, (S/N = 3). These results prove that the developed electrode material has high sensitivity, stability, and selectivity for the detection of the CA-125 antigen. In addition, this study can be reasonable for the practical detection of CA125 in serum, permitting early cancer diagnostics and convenient treatment.
Optimization of Electrode Preperation Conditions for Enhanced Glucose Electrooxidation on Pt/Cnt by Response Surface Methodology
(Springer, 2022) Kaya, Sefika; Ulas, Berdan; Er, Omer Faruk; Kivrak, Hilal; Yilmaz, Yonca
In this study, glucose electrooxidation activities of carbon nanotube (CNT)-supported Pt catalysts synthesized at various weight percentages and optimum electrode preparation conditions are investigated. For glucose electrooxidation on Pt/CNT, electrode preparation parameters such as amount of catalyst ink (V-c), ultrasonication duration of the catalyst ink (d(u)), and drying duration of the electrode (d(d)) were optimized to obtain maximum specific activity. The catalysts (Pt/CNT) are characterized via N-2 adsorption-desorption, X-ray diffraction, and electron microscopy with energy dispersive X-ray advanced surface analysis techniques. Specific activity for glucose electrooxidation catalyst performance are determined by using cyclic voltammetry (CV) and chronoamperometry (CA) measurements. According to CV measurements, the best electrocatalytic activity obtained is 3.4352 mA/cm(2) with 7% Pt/CNT catalyst. Experimental conditions are optimized via response surface methodology (RSM) for maximizing glucose electrooxidation activity. The predicted specific activity and the actual specific activity are determined to be 5.931 mA/cm(2) and 5.421 mA/cm(2) under optimum conditions such as 7.36 mu L (V-c), 49.54 min (d(d)), and 2.45 min (d(u)).
Remarkable Bismuth-Gold Alloy Decorated on Mwcnt for Glucose Electrooxidation: the Effect of Bismuth Promotion and Optimization Via Response Surface Methodology
(Tubitak Scientific & Technological Research Council Turkey, 2021) Er, Omer Faruk; Ulas, Berdan; Demir Kivrak, Hilal
In this study, the carbon nanotube supported gold, bismuth, and gold-bismuth (Au/MWCNT, Bi/MWCNT, and Au-Bi/ MWCNT) nanocatalysts were prepared with NaBH4 reduction method at varying molar atomic ratio for glucose electrooxidation (GAEO). The synthesized nanocatalysts at different Au: Bi atomic ratios are characterized via x-ray diffraction (XRD), transmission electron microscopy (TEM), and N-2 adsorption-desorption. For the performance of AuBi/MWCNT for GAEO, electrochemical measurements are performed by using different electrochemical techniques namely cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS). Monometallic Au/MWCNT exhibits higher activity than Bi/MWCNT with 256.57 mA/mg (0.936 mA/cm(2)) current density. According to CV results, Au80Bi20/MWCNT nanocatalyst has the highest GAEO activity with the mass activity of 320.15 mA/mg (1.133 mA/cm(2)). For Au80Bi (20)/MWCNT, central composite design (CCD) is utilized for optimum conditions of the electrode preparation. Au80Bi20/MWCNT nanocatalysts are promising anode nanocatalysts for direct glucose fuel cells (DGFCs).