Electrochemical immunosensor based on magnetite nanoparticles incorporated electrospun polyacrylonitrile nanofibers for Vitamin-D3 detection.

In the present study, magnetite nanoparticles (Fe3O4 NPs) incorporated polyacrylonitrile nanofibers (PANnFs) having diameter of 350-500 nm, were electrospun and directly collected onto indium tin oxide (ITO) coated glass substrate. X-ray diffraction pattern of Fe3O4‑PANnFs confirmed the existence of Fe3O4 NPs within the PANnFs. Nafion was used to make Fe3O4‑PANnFs more adhesive to the ITO surface. Partial hydrolyzation of Fe3O4‑PANnFs/ITO electrode was done using NaOH solution for the partial conversion of nitrile group (C≡N) into carboxyl and amine groups that was confirmed by Fourier transform infrared spectroscopy study. The hydrolyzed Fe3O4‑PANnFs/ITO electrode was used as an immobilization matrix for monoclonal antibody specific to Vitamin-D3 (Anti‑VD) via 1‑ethyl‑3‑(3‑dimethylaminopropyl) carbodiimide and N‑Hydroxysuccinimide chemistry. Bovine serum albumin (BSA) was used as a blocking agent to block the non-specific sites onto Anti‑VD/Fe3O4‑PANnFs/ITO electrode surface. Fabricated BSA/Anti‑VD/Fe3O4‑PANnFs/ITO immunoelectrode showed improved biosensing parameters for Vitamin-D3 detection such as sensitivity of 0.90 μA ng-1 mL cm-2, limit of detection of 0.12 ng mL-1and detection range of 10-100 ng mL-1. The association and dissociation constants were obtained as 74.62 ng mL-1, 4.6 ng mL-1, respectively.