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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; Çalışkan, Meltem; Bilgi Kamaç, 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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    A disposable biosensing system for analysis of CA125 in real human serum samples
    (Tubitak Scientific & Technological Research Council Turkey, 2025) Afşar, Meltem; Vural, Berfin; Bilgi Kamaç, Melike; Sezgintürk, Mustafa Kemal
    Several biomarkers have been developed to track the development of ovarian cancer and identify the illness at an early stage. A promising development for ovarian cancer is using cancer antigen 125 (CA125). The objective of this work is to identify the CA125 marker by utilizing an indium tin oxide polyethylene electrode. The advantage of the designed biosensor is that it is very cheap, disposable, practical, and easy to use. The necessary parameters for the developed biosensor have been optimized in detail. Repeatability, reproducibility, regeneration, storage, and selectivity studies have been completed to characterize the proposed biosensor. Electrochemical impedance spectroscopy and cyclic voltammetry techniques were used for all experimental investigations of the proposed biosensor. The immunosensor offers a large linear detection range (0.01-100 pg/mL). Moreover, this developed sensor has a 0.018 pg/mL limit of detection and a 0.06 pg/mL limit of quantification. The high accuracy of this biosensor was observed in five commercial human serums.
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    A label-free dual immunosensor for the simultaneous electrochemical determination of CA125 and HE4 biomarkers for the early diagnosis of ovarian cancer
    (Springer Science and Business Media Deutschland GmbH, 2023) Bilgi Kamaç, Melike; Altun, Muhammed; Yılmaz, Merve; Sezgintürk, Mustafa Kemal
    The blood levels of cancer antigen 125 (CA125) and human epididymal secretory protein 4 (HE4) are measured in the diagnosis and progression monitoring of ovarian cancer (OC), and the Risk of Ovarian Malignancy Algorithm (ROMA) score% values are calculated for cancer risk assessment. For the first time, disposable dual screen-printed carbon electrodes modified with reduced graphene oxide, polythionine, and gold nanoparticles were used to fabricate label-free electrochemical dual CA125-HE4 immunosensors for the sensitive, fast, and practical simultaneous determination of CA125 and HE4. DPV and SWV methods were used to simultaneously determine antigens in two different linear ranges (1–100 pg mL−1 and 1–50 ng mL−1). High sensitivity, low LOD, and LOQ were obtained for two linear ranges with a correlation coefficient above 0.99. The application stability of the dual CA125-HE4 immunosensors was determined as 60 days, and the storage stability was determined as 16 weeks. The dual immunosensors exhibited high selectivity in eight different antigen mixtures. The reusability of the dual immunosensors has been tested up to 9 cycles. ROMA score% values for pre-menopausal and post-menopausal status were calculated using the concentration of CA125 and HE4 in the blood serum and assessing OC risk. The disposable dual immunosensors can be used in point-of-care tests for rapid and practical simultaneous determination of CA125 and HE4 with high selectivity, sensitivity, and repeatability.
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    Point-of-care testing: a disposable label-free electrochemical CA125 and HE4 immunosensors for early detection of ovarian cancer
    (Springer, 2023) Bilgi Kamaç, Melike; Altun, Muhammed; Yılmaz, Merve; Yılmaz Aktan, Ayla; Aktan, Soner; Sezgintürk, Mustafa Kemal
    Cancer antigen 125 (CA125) and human epididymal secretory protein 4 (HE4) are critical biomarkers for ovarian cancer diagnosis and progression monitoring; therefore, sensitive determination of their levels in body fluids is crucial. In recent study, label-free CA125 and HE4 immunosensors were prepared using disposable screen-printed carbon electrodes modified with reduced graphene oxide, polythionine, and gold nanoparticles for the sensitive, fast, and practical determination of CA125 and HE4. Differential pulse voltammetry, square wave voltammetry, and electrochemical impedance spectroscopy methods were used for the electrochemical determination of antigens in four different linear ranges (1-100 pg mL− 1, 0.01-10 ng mL− 1, 10–50 ng mL− 1, and 50–500 ng mL− 1). High sensitivity, low limit of detection, and limit of quantification were obtained for each linear range with a correlation coefficient above 0.99. The application stability of CA125 and HE4 immunosensors was determined as 60 days, and the storage stability was determined as 16 weeks. Immunosensors showed high selectivity in nine different antigen mixtures. The reusability of the immunosensors has been tested up to 9 cycles. The Risk of Ovarian Malignancy Algorithm score% values were calculated using the concentration of CA125 and HE4 in the blood serum and evaluated in terms of ovarian cancer risk. For the point-of-care testing, CA125 and HE4 levels at pg mL− 1 concentration were measured in blood serum samples using the developed immunosensors and a hand-held electrochemical reader in approximately 20–30 s, and high recoveries were obtained. These disposable label-free immunosensors are user-friendly and can be used in point-of-care tests for rapid and practical detection of CA125 and HE4 with high selectivity, sensitivity, and repeatability.