Molecularly imprinted polymers-based electrochemical DNA biosensor for the determination of BRCA-1 amplified by SiO₂@Ag

A novel electrochemical DNA (E-DNA) biosensing strategy was designed and used for the detection of breast cancer susceptibility gene (BRCA-1). The biosensor was based on gold nanoparticles-reduced graphene oxide (AuNPs-GO) modified glass carbon electrode (GCE) covered with the layer of molecularly imprinted polymers (MIPs) synthesized with rhodamine B (RhB) as template, methacrylic acid (MAA) as the monomer, and Nafion as additive. The signal amplification tracing tag SiO₂@Ag NPs were prepared by covering AgNPs on the surface of SiO₂ nanoparticles in situ, and then DNA probes were modified on AgNPs by Ag-S bond, forming the composites SiO₂@Ag/DNA. In presence of target DNA (T-DNA), homogeneous hybridization was performed with SiO₂@Ag/DNA and RhB labeled DNA, and the resulting SiO₂@Ag/dsDNA/RhB was specifically recognized by MIPs via the interaction between imprinting cavities and RhB. Under optimal conditions, the proposed biosensor exhibited wide linear range from 10 fM to 100 nM, low detection limit of 2.53 fM (S/N = 3), excellent selectivity, reproducibility, stability, and feasibility in serum analysis. Overall, these findings suggest the promising prospects of the proposed biosensing strategy in clinical diagnostics.