A label-free electrochemical biosensing strategy based on gold nanoparticle involved layer-by-layer self assembly for the detection of protein is proposed using platelet derived growth factor-BB dimer (PDGF-BB) as the model analyte. Utilizing the strong sulfur-Au affinity, ethanthiol and capture probe modified gold nanoparticles are self-assembled onto the surface of gold electrode successively. The aptamer probe for target protein hybridizes with the capture probe and the biosensor is fabricated. By measuring ac current voltammetry, the target protein can be sensitively detected in a linear dynamic range from 1-1000 ng/mL with a low detection limit of 0.5 ng/mL. Making use of self-assembled gold nanoparticles layer, a large amount of capture probes can be modified onto the gold electrode, supporting the high sensitivity of the proposed strategy. In addition, good reproducibility, high selectivity and stability are achieved. In particular, the biosensor can be easily regenerated by melting in hot water, making it reusable.
Polymer-based multiferroic nanocomposites via directed block copolymer self-assembly