Redox hydrogel based immunosensing platform for the label-free detection of a cancer biomarker

Abstract

A redox hydrogel was prepared from the ferrocene (Fc) modified amino acid, phenylalanine (Phe, F), and utilized to construct an immunosensing platform for the label-free detection of a cancer biomarker prostate specific antigen (PSA). The synthesized hydrogel contains a large number of Fc moieties, which imparts the hydrogel with redox properties. The hydrogel modified electrode displays a pair of reversible redox peaks, indicating the facile electron transfer of Fc in the hydrogel at the electrode surface. After the immobilization of the anti-PSA antibody onto the hydrogel modified electrode surface and the capture of PSA molecules, the redox current at the electrode was suppressed significantly due to the blocking of the electron transfer at the electrode surface by the formed immuno-complex. The current change was proportional to the concentration of PSA detected in the range from 1 pg mL⁻¹ to 10 ng mL⁻¹ with a detection limit of 0.5 pg mL⁻¹. The proposed immunosensor is simple with a low cost and high sensitivity, which could find wide clinical applications.