Plastic antibody for the electrochemical detection of bacterial surface proteins

This work presents a novel molecularly imprinted polymer (MIP) for the indirect detection of bacteria, by targeting an outer membrane protein on a disposable device. Protein A (PA) was selected for this purpose, as a representative protein of the outer surface of Staphylococcus aureus. The imprinted polymer was assembled directly on a film of single walled carbon nanotubes (SWCNTs), placed on screen-printed electrodes (SPEs). The MIP material was produced by electropolymerizing 3-aminophenol in the presence of the protein template (PA) using cyclic voltammetry (CV). The proteins entrapped at the polymeric backbone were digested by the action of proteolytic activity of proteinase K and then washed away to create vacant sites. The performance of the corresponding imprinted and non-imprinted electrodes was evaluated by EIS and the effect of several variables, such as monomer and template concentrations, or thickness of imprinting surface, was controlled and optimized by the number of CV cycles. The detection limit of the MIP-based sensors was 0.60 nM in MES buffer. High repeatability and good selectivity were observed in the presence of a model protein BSA. The sensor performance was also tested to check the effect of inorganic ions in tap water. The detection limit observed was 16.83 nM, with a recovery factor of 91.1 + 6.6%. The sensor described in this work is a potential tool for screening PA on-site, due to the simplicity of fabrication, disposability, short response time, low cost, good sensitivity and selectivity. (C) 2016 Elsevier B.V. All rights reserved.