Development of All-Solid-State Antidiabetic Drug Metformin-Selective Microsensor and Its Electrochemical Applications

WOS: 000514639500001In this study, all-solid-state type potentiometric PVC membrane selective microsensor was developed for Metformin (MET) which is an antidiabetic drug active substance. Metformin-tetraphenylborate (MET-TPB) ion-pair was used as an ionophore in the structure of the sensor membrane. It was determined that the sensor membrane at the ratio of 69 % o-nitrophenyl octyl ether, 27 % polyvinyl chloride and 4 % MET-TPB performed the best potentiometric performance. in a wide concentration range (1x10(-5)-1x10(-1) mol/L), the slope, detection limit, response time, pH range, and life-time of the sensor were determined as 55.9 +/- 1.6 mV (R-2=0.996), 3.35x10(-6) mol/L, 8-10 s, pH: 3-8, and similar to 10 weeks, respectively. the voltammetric performances of the sensor were also investigated. the prepared microsensor was successfully utilized for the determination of Metformin in a pharmaceutical drug sample by potentiometry and voltammetry. It was observed that the obtained results were in agreement with the results obtained by the UV spectroscopy method at 95 % confidence level

Cold substrate method to prepare plasmonic Ag nanoparticle: deposition, characterization, application in solar cell

Tomakin, Murat/0000-0003-1887-848XWOS: 000518475700001In this study, the surface plasmon effects of the Ag nanoparticle were investigated depending on the substrate temperature and coating time. Deposition procedure for the Ag coating was the vacuum deposition at low substrate temperature (< 300 K) instead of the commonly used the vacuum deposition at high substrate temperatures. the Ag thin films were deposited on n-type Si, glass and solar cell with safety glass substrates. the structural and optical characteristics of the Ag thin films prepared on Si and glass substrates were investigated. the Ag thin films had a polycrystalline structure with cubic phase. the (111) preferred orientation for 300 K substrate temperature was changed to (200) after 200 K substrate temperature. Homogeneous nano-sized Ag particles on Si were obtained at the 150-200 K temperature range. Optical measurements were performed for the Ag thin films prepared on glass substrates. According to reflectance measurements, plasmon resonance effect of the Ag nanoparticles was observed around 435-540 nm. the Ag nanoparticles prepared on solar cell at low substrate temperature increased the solar cell efficiency for all coating time because the nanoparticle size and shape were not changed significantly with the coating time. However, the Ag thin films prepared at high substrate temperature decreased device efficiency with the increasing coating time

Centri-voltammetric detection of epinephrine

Varol, Tugba Oren/0000-0003-3680-5743; anik, ulku/0000-0002-3607-7208;WOS: 000385380800006The present study demonstrates a novel approach that has been proposed for epinephrine detection by using centri-voltammetry. the principle of the method is based on the accumulation of an analyte, here epinephrine, onto an electrode surface via centrifugal force. After the accumulation of epinephrine, a direct voltammetric scan was performed in a specially fabricated centri-voltammetric cell. A remarkable increase in the oxidation peak current of epinephrine was observed in the case of centrifuge application. Experimental parameters like the centrifugation speed and centrifugation time were optimized and then the analytical characteristics were examined. Two linear ranges were obtained between 0.2-20 mu M and 50-500 mu M for epinephrine and limit of detection (LOD) values were also calculated for both linear ranges to be 0.013 mu M and 0.043 mu M, respectively. As a practical application, the developed method was applied to epinephrine detection in adrenaline ampoule samples

A biochar-modified carbon paste electrode

WOS: 000403692800014The present work examined the use of biochar derived from tea waste as a novel electrode material. For the fabrication of the biochar electrode, suitable amounts of biochar and graphite were mixed with mineral oil for the first time. The electrochemical performance of the biochar-modified carbon paste electrode (BCPE) was measured by various cyclic voltammetric reactions for several redox systems. The factors affecting the electrode kinetics of BCPE surfaces were examined and optimized. The BCPE was applied as transducer in a glucose biosensor. The results reflect the effective properties of composite electrodes and the electrochemical properties of biochar showing that the BCPE could be used for various electrochemical applications.Recep Tayyip Erdogan University, Scientific Research Projects Coordinator Unit (BAP) [RTEU - 2014.29.109.04.01, RTEU - 2015.53008.109.07.01]We gratefully acknowledge the financial support for chemical analyses provided by Recep Tayyip Erdogan University, Scientific Research Projects Coordinator Unit (BAP) (Project No: RTEU - 2014.29.109.04.01 and RTEU - 2015.53008.109.07.01)

Synthesis and characterization of activated carbon produced from waste human hair mass using chemical activation

WOS: 000553643500008In this study, hair waste was converted into active carbon for the first time and its characteristics were analyzed. As chemical activation tool, zinc chloride (ZnCl2) was impregnated and then carbonized under different temperatures (250-300 degrees C). Scanning Electron Microscope (SEM) images showed an increase in the pore density, radius and volume of pores. X-ray diffraction analysis (XRD) showed that the samples had an amorphous structure. in Fourier-transform infrared (FT-IR) spectroscope analysis, C=C and N-H vibrations observed in 1515-1520 cm(-1)wave number of protein molecules were found to disappear with the increase in temperature. With Raman spectroscopy, the behaviors of D peak at 1344 cm(-1)wave number and G peak at 1566 cm(-1)wave number expressing structure layout in carbonized structures were analyzed depending on the temperatures. Between these intensities, (I-D/I-G) the rate was found to differ in direct proportion to temperature. XRD spectrums showed that the samples are converted into a more irregular crystal structure. All these results implied that the waste hair mass could be used as an adsorbant material

Synthesis of new carbon material produced from human hair and its evaluation as electrochemical supercapacitor

Aslan, Sema/0000-0001-9796-7311WOS: 000548157000001In this study, carbon material similar to graphene structure (GLS) was prepared from graphite and the carbonization of Turkish human hair fibers (HHC) and utilized for the modification of electrode to evaluate the supercapacitance performance. Electrochemical characterization of the HHC-based GLS (HHC-GLS) modified electrodes have been carried out with cyclic voltammetry and electrochemical impedance spectroscopy. the morphology and chemical composition of the resultant GLSs were characterized by scanning electron microscopy, X-Ray diffraction spectroscopy, Raman and Fourier Transform infrared spectroscopy analysis. HHC-GLS displayed a good electrochemical activity than the graphite sourced graphene and possess very similar morphological properties with commercial graphene. Carbonization of the waste hair was carried out at 280 degrees C to improve the pore structure as the first step of GLS synthesis. HHC-GLS modified electrode exhibited the best electrochemical activity and utilized as a charge storage device. the best specific capacitance value was found to be 139.00 F g(-1)in 6.00 M KOH((aq))at a scan rate of 100.00 mV s(-1)and good stability over 500 cycles. Whereas an energy density of 19.3 Wh kg(-1)and power density of 6.95 kW kg(-1)were obtained from the electrode when operated in the voltage range from -1.00 to 0.00 V. This work offers a new approach to human hair waste management in terms of promising green energy applications. This study was patented by the Turkish Patent and Trademark Office (Turkish Patent Institute Application Number: (2019/22841))

Electrochemical Evaluation of Titanium (IV) Oxide/Polyacrylonitrile Electrospun Discharged Battery Coals as Supercapacitor Electrodes

KOCAK, Cagdas/0000-0003-2195-7218WOS: 000564583100001The TiO(2)nanoparticles are electrospun with polyacrylonitrile (PAN) polymer solution onto the discharged battery coal (DBC) electrode and the results are evaluated as a supercapacitor. the morphology and chemical composition of the synthesized TiO(2)nanoparticles and PAN+TiO(2)nanocomposite fibers were characterized by Scanning electron microscopy, thermogravimetry and FTIR analysis. Supercapacitor measurements and electrochemical characterizations of the electrodes examined by cyclic voltammetry and electrochemical impedance spectroscopy. Electrochemical measurements showed that the best current value was obtained from PAN and TiO(2)coated DBC. the performances of both PAN and PAN+TiO(2)coated DBC electrodes were investigated as supercapacitors. PAN+TiO2/DBC showed the best specific capacitance value of 156.00 F g(-1)and PAN/DBC showed 74.93 F g(-1). in addition, PAN+TiO2/DBC exhibited reliable stability performance over 2000.00 cycles

An Electrochemical Immuno-cytosensor Modified with Nanofibers for the Determination of a Carcinoembryonic Antigen

In this study, La0.25Fe0.75FeO3 (PNp)perovskite nanoparticle was synthesized using the sol-gel method. PNp-coated polyacrylonitrile (PAN) nanofibers were prepared by electrospinning on the pencil graphite electrode (PGE) surface. In another step, carcinoembryonic antigen (CEA) was loaded with CEA antibodies (Anti-CEA) as a biomarker receptor. Finally, PGE/PAN@PNp/Anti-CEA was used for CEA detection. Optimization steps and cell culture steps were performed using differential pulse voltammetry (DPV). The use of this composite system is a novel immunosensor development approach for label-free detection of CEA. Under optimum conditions, detection limit (LOD) of PGE/PAN@PNp/Anti-CEA immunosensor LOD 1.48 ng/mL, limit of quantification (LOQ) = 4.94 ng/mL, reproducibility 1.46% (n = 5) and R2 = 0.9984 for antigen concentration within a linear working range of 0.1-10 ng/mL. Also, immunosensor recovery in real serum samples containing dopamine and ascorbic acid was found as 98.94 +/- 7.43. It has great potential in clinical screening of different cancer biomarkers. The number of cells attached to the PGE/PAN@PNp/Anti-CEA/BSA(bovine serum)/CEA surface decreased in RT-4(bladder cancer), MDA-MB-231 (triple-negative breast adenocarcinoma cell line), and T98G cells (glioblastoma multiforme cell line), which are known as CEA-negative cell lines, whereas the number of MCF-7 cells (estrogen-sensitive human breast cancer cell line, known to be CEA positive) attached to the PGE/PAN@PNp/Anti-CEA/BSA/CEA surface increased, indicating higher affinity to the immunosensor surface. As a result, while MCF-7, which is CEA positive, can be determined best when using an immune-cytosensor, the cell that can be best determined with cytosensors was found to be RT-4.Scientific and Techno-logical Research Council of Turkiye (TUBIdot;TAK); Recep Tayyip Erdogan University Development FoundationOpen access funding provided by the Scientific and Techno-logical Research Council of Turkiye (TUB ; Idot;TAK).This article was supported by Recep Tayyip Erdogan University Development Foundation