A reusable electrochemical biosensing strategy based on gold nanoparticle involved layer-by-layer self-assembly for sensitive detection of single nucleotide polymorphisms is proposed in this study. Making use of the strong sulfur-Au affinity, ethanthiol and capture probe modified gold nanoparticles are self-assembled onto the surface of gold electrode successively. The target DNA hybridizes with the capture probe and ferrocene labeled signaling probe successively via sandwich hybridization reaction. By measuring ac current voltammetry, the target DNA can be sensitively detected in a linear dynamic range from 4.1-410 nM with a low detection limit of 2 nM. 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.
A ferrofluid-based homogeneous assay for highly sensitive and selective detection of single-nucleotide polymorphisms
