Ultrasensitive electrochemical immunosensor based on horseradish peroxidase (HRP)-loaded silica-poly(acrylic acid) brushes for protein biomarker detection

摘要

We report an ultrasensitive electrochemical immunosensor designed for the detection of protein bio-markers using horseradish peroxidase (HRP)-loaded silica-poly(acrylic acid) brushes (SiO2-SPAABs) as labels. HRP could be efficiently and stably accommodated in the three-dimensional architecture of the SiO2-SPAABs and the SiO2-SPAABs-HRP exhibited high catalytic performance towards o-phenylenediamine (OPD) oxidation in the presence of H2O2, which resulted in significant differential pulse voltammetric (DPV) response change and color change. Using human IgG (HIgG) as a model analyte, a sandwich-type immunosensor was constructed. In particular, graphene oxide (GO) and SiO2-SPAABs-HRP were used to immobilize capture antibody (Ab(1)) and bind a layer of detection antibody (Ab(2)), respectively. The current biosensor exhibited a good linear response of HIgG from 100 pg/mL to 100 mu g/mL with a detection limit of 50 pg/mL (S/N= 5). The sensitivity was 6.70-fold higher than the conventional enzyme-linked immunosorbent assays. The immunosensor results were validated through the detection of HIgG in serum samples. (C) 2015 Elsevier B.V. All rights reserved.