Gold-platinum bimetallic nanoparticles coated 3-(aminopropyl) triethoxysilane (APTES) based electrochemical immunosensor for vitamin D estimation

We have developed a gold-platinum nanoparticles (Au-Pt NPs) supported on 3-(aminopropyl)triethoxysilane (APTES) modified fluorine tin oxide (FTO) glass electrode as a biosensing platform for the detection of 25-hydroxy vitamin D-3 (25(OH)D-3). The Au-Pt NPs were electro-deposited onto the APTES modified FTO electrode using chronoamperometry at a constant potential of -0.2 V for 350 s. The antibody against vitamin D-3 (Ab-25(OH)D-3) was immobilized covalently via glutaraldehyde cross linking chemistry. The successful immobilization of the matrix was confirmed through characterization techniques like FE-SEM, FT-IR, XRD, XPS, contact angle measurement, electrochemical characterizations such as cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). The DPV technique was employed for the detection of 25(OH)D-3 using ferricyanide/ferrocyanide solution [Fe (CN)(6)](3-/4-) as a redox mediator. The immunosensor presented a detection limit of 0.49 pg/mL with a quick response time of 12 min and an acceptable stability of 10 days, if stored at 4 degrees C. The proposed immunosenor is highly selective and sensitive for 25(OH)D-3 and could be employed for the real-time quantification of vitamin D.