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Öğe A new electrochemical impedance biosensor based on aromatic thiol for alpha-1 antitrypsin determination(Tubitak Scientific & Technological Research Council Turkey, 2021) Yagar, Huelya; Ozcan, Hakki Mevluet; Mehmet, OsmanAlpha-1 antitrypsin (A1AT) is one of the acute phase proteins which are synthesized in the liver. A1AT inhibits the activity of many proteases, but its main task is to protect the lungs from the attack of neutrophil elastase. In an autosomal hereditary disease known as alpha-1 antitrypsin deficiency, the A1AT level in blood serum decreases, increasing the risk of developing emphysema, liver apoptosis, and liver cancer. Thus, the detection of A1AT concentration in blood serum is very important. In this study, an impedimetric biosensor was developed, forming an SAM (self-assembled monolayer) with 4-mercaptophenylacetic acid (4MPA) on the surface of the gold electrode. An A1AT biosensor was constructed using immobilization of an A1AT-specific antibody (anti-A1AT) after activating the carboxyl groups of 4MPA with EDC/NHS. Each immobilization stage was characterized by using electrochemical impedance spectroscopy, cyclic voltammetry, and scanning electron microscopy with energy dispersive X-ray spectroscopy. With the designed biosensor, precise and highly reproducible results were obtained for A1AT concentrations in the range of 100-600 mu g/mL. A1AT detection was also successfully carried out in artificial serum solutions spiked with A1AT.Öğe A new multienzyme-type biosensor for triglyceride determination(Taylor & Francis Inc, 2016) Yucel, Alp; Ozcan, Hakki Mevluet; Sagiroglu, AytenAn amperometric multienzyme biosensor for determination of triglycerides (TGs) was constructed by mounting three gelatin membrane-bound enzymes on a glassy carbon electrode (working electrode), then connecting it to electrometer along with an Ag/AgCl reference electrode and a Pt auxiliary electrode. Characterization and optimization of the multienzyme biosensor, which is prepared with glycerol kinase (GK) (E.C.2.7.1.30), glycerol-3-phosphate oxidase (GPO) (EC 1.1.3.21), and lipase (EC 3.1.1.3), were studied. In the optimization studies for the bioactive layer components of the prepared biosensor, the optimum amounts of gelatin, bovine serum albumin (BSA), and glutaraldehyde was calculated as 1mg/cm(2), 1mg/cm(2), and 2.5%, respectively. Optimum pH and temperature of the reaction of biosensor were determined as 7.0 and 40 degrees C, respectively. Linear range of triolein for the biosensor was found from the calibration curve between several substrate concentration and Current. After optimization and characterization of the biosensor, its operationability in triglycerides was also tested.