Browsing by Author "Demirhan, Alper"

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Citation - WoS: 4
Citation - Scopus: 4
Low-Cost High-Resolution Potentiostat for Electrochemical Detection of Nucleic Acids and Biomolecular Interactions
(Mdpi, 2022) Demirhan, Alper; Eksin, Ece; Kilic, Yalin; Erdem, Arzum
A handheld USB-powered instrument developed for the electrochemical detection of nucleic acids and biomolecular interactions is presented. The proposed instrument is capable of scanning +/- 2.25 V while measuring currents up to +/- 10 mA, with a minimum current resolution of 6.87 pA. Therefore, it is suitable for nucleic acid sensors, which have high background currents. A low-cost microcontroller with an on-chip 16-bit analog-to-digital converter, 12-bit digital-to-analog converter, and a built-in USB controller were used to miniaturize the system. The offset voltages and gain errors of the analog peripherals were calibrated to obtain a superior performance. Thus, a similar performance to those of the market-leader potentiostats was achieved, but at a fraction of their cost and size. The performance of the application of this proposed architecture was tested successfully and was found to be similar to a leading commercial device through a clinical application in the aspects of the detection of nucleic acids, such as calf thymus ssDNA and dsDNA, and their interactions with a protein (BSA) by using single-use graphite electrodes in combination with the differential pulse voltammetry technique.
Citation - WoS: 21
Citation - Scopus: 22
Quantitative Determination of H2o2 for Detection of Alanine Aminotransferase Using Thin Film Electrodes
(Academic Press Inc Elsevier Science, 2020) Saygili, Ecem; Orakci, Beyza; Koprulu, Melisa; Demirhan, Alper; Ilhan-Ayisigi, Esra; Kilic, Yalin; Yesil-Celiktas, Ozlem
The abnormal concentrations or absence of biomolecules (e.g., proteins) in blood can further be used in diagnosis of a particular pathology at an early stage. Current studies are intensely focusing on the analysis of interaction and detection of biomolecules via point-of-care systems (POCs), allowing miniaturized and parallelized reactions, simultaneously. Recent developments have shown that the collaboration of electrochemical sensing techniques and POCs to overcome challenging problems in health-care settings provides new approaches in diagnosis and treatment of diseases. The aim of this study was to adapt the alanine aminotransferase (ALT) enzyme to the platinum (Pt) thin film electrode system and quantitatively determine the enzyme levels via enzymatically generated H2O2 with differential pulse voltammetry (DPV). A simple potentiostat architecture with expanded sweep range utilizing dual LMP91000 devices was developed and adapted to the needs of the biosensor. In order to calibrate the system, known concentrations of H2O2 were also tested. Moreover, signals associated with the other electroactive species coming from the ALT reaction were eliminated. Resulted potential range has been achieved between +500 mV and + 900 mV and the linear range was found to be 0.05 M-0.5 M for H2O2, whereas 5 UL-1 to 120 UL-1 for ALT enzyme.