A label-free electrochemical DNA biosensor for breast cancer marker BRCA1 based on self-assembled antifouling peptide monolayer

Electrochemical assays potentially offer a highly cheap, automated, portable and sensitive method for a great deal of disease biomarker detections, and minimization of nonspecific adsorption is a critical issue for their application in natural complex media. We present herein, the development and application of a highly sensitive and selective electrochemical DNA hybridization biosensor for breast cancer marker BRCA1, based on a zwitterionic peptide self-assembled monolayer (SAM) support serving as the low fouling substrate, the 19-mer BRCA1 related sequence-specific oligonucleotides, and the sensitively label-free sensing technique of electrochemical impedance spectroscopy (EIS). The capability of such peptide SAM in resisting nonspecific protein adsorption was surveyed using EIS, and the biosensor fabrication process and sensing performance were also investigated with X-Ray photoelectron spectroscopy (XPS) and EIS. Significantly, this developed biosensing strategy achieved a linear detection range from 1.0 fM to 10.0 pM with a limit of detection of 0.3 fM, associated with satisfactory sensing properties of facile fabrication, desired sensitivity, high selectivity, and favourable reproducibility and antifouling ability, manifesting its promising potential in practical application.