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    A disposable and ultrasensitive immunosensor for the detection of HE4 in human serum samples
    (Springer Int Publ Ag, 2024) Vural, Berfin; Caliskan, Meltem; Bilgi Kamac, Melike; Sezgintürk, Mustafa Kemal
    Ovarian cancer is described as excessive cell proliferation in the ovaries. It is thought that ovarian cancer and the human epididymis protein 4 (HE4) are closely linked. HE4 is approved as a critical biomarker for the diagnosis and the progression monitoring of the ovarian cancer. In this work, an impedimetric biosensor was fabricated for the analysis of HE4 by modifying the surface of disposable ITO-PET (indium tin oxide-polyethylene terephthalate) sheet with a certain dimensions by 3-Aminopropyl trimethoxy silane (3-APTES). For the interaction between the amino ends of 3-APTES and anti-HE4 antibodies glutaraldehyde was used as a cross-linker. Electrochemical impedance (EIS) and cyclic voltammetry (CV) methods were applied in all electrochemical measurements. Important optimization and characterization experiments have also been completed. Under the optimum conditions, the concentration range for HE4 was obtained between 1 pg/mL and 3000 pg/mL with an LOD and LOQ values of 0.094 pg/mL and 0.3134 pg/mL, respectively. Selectivity experiments revealed that the biosensor showed a great selectivity with its target HE4. The biosensor also showed a good reproducibility with a relative standard deviation (RSD) of slope data calculated as 2.443%. Finally, we applied the biosensor to the commercial real human serum samples for analysis of HE4 and the results of these experiments were encouraging to be used in clinical settings.
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    Öğe
    A Novel Disposable Immunosensor for Early Diagnosis of Cardiovascular Diseases
    (Wiley-V C H Verlag Gmbh, 2022) Caliskan, Meltem; Vural, Berfin; Sezgintürk, Mustafa Kemal
    Cardiovascular diseases are highly common cause of mortality and morbidity. It is envisaged that there is a relationship between cardiovascular diseases and ST2 (Suppression of Tumorigenicity 2) concentration of protein. In patients with cardiac insufficiency, the ST2 concentration was reported as higher than people without cardiac insufficiency. In this study ITO-PET sheets (indium tin oxide covered terephthalate) was used as a working electrode for the fabrication of the immunosensor for ST2 protein. In the optimization experiments, important parameters responsible for biosensor fabrication have been optimized. After determining optimal conditions, reproducibility, repeatability, regeneration possibility, and analytical properties such as storage life are determined. The immunosensor showed a linear detection range for ST2 between 1-1500 fg/mL with a LOD value of 3.98 fg/mL. We also carried out SFI (single frequency impedance) experiments to monitor the specific interaction between ST2 and anti-ST2, simultaneously. The developed immunosensor was successively applied to the determination of ST2 in commercial human serum sample.
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    Öğe
    Development of a biosensor platform based on ITO sheets modified with 3-glycidoxypropyltrimethoxysilane for early detection of TRAP1
    (Tubitak Scientific & Technological Research Council Turkey, 2020) Vural, Berfin; Caliskan, Meltem; Sezgintürk, Mustafa Kemal
    The aim of this research was to design an electrochemical immunosensor for determination of tumour necrosis factor receptor-associated protein-1(TRAP1) antigen, a heat shock protein linked to tumour necrosis factor. The indium-tin oxide covered polyethylene terephthalate (ITO-PET) electrode surface was cleaned and was prepared for the introduction of hydroxyl groups on its surface by using NH4OH/H2O2/H2O. As a silanization agent for covalent attachment of anti-TRAP1 on the surface of the ITO working electrode, 3-glycidoxypropyltrimethoxysilane (3-GOPS) was used. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to characterize the immobilization steps. A variety of parameters, 3-GOPS and anti-TRAP1 concentrations, and anti-TRAP1 and TRAP1 incubation durations were optimized. After determining the optimum conditions, characterization studies such as repeatability, reproducibility, regeneration, square wave voltammetry, and single frequency impedance were performed. The electrochemical immunosensor has presented an extremely wide determination range for TRAP1 from 0.1 pg/mL to 100 pg/mL.