Functional DNA-peptide conjugates with enhanced antifouling capabilities for electrochemical detection of proteins in complex human serum

Electrochemical biosensors with high sensitivity and cost-effectiveness, are considered as a promising alternative to existing clinical diagnostic techniques, but their practical assaying application in complex biological samples was significantly limited by the severe biofouling. Herein, an electrochemical biosensing platform with enhanced antifouling abilities was constructed based on a designed DNA-peptide conjugate, which was synthesized with an anchoring DNA and a difunctional (antifouling and recognizing) peptide. The DNA-peptide conjugates were easily immobilized onto an electrode, which was modified with poly(3,4-ethylenedioxythiophene) (PEDOT) and gold nanoparticles (AuNPs), through the interaction between the anchoring DNA and AuNPs, and the recognizing peptide was specific for the binding of target human immunoglobulin G (IgG). As both the anchoring DNA and the difunctional peptide possessed antifouling abilities, the IgG biosensor based on the DNA-peptide conjugates exhibited enhanced antifouling properties, and it was capable of detecting IgG directly in real human serum, with a wide linear range from 0.1 ng·mL−1-10 μg·mL−1 and a low limit of detection (0.037 ng·mL−1). The strategy of developing biosensors with functional DNA-peptide conjugates as antifouling materials offered an effective and simple way to achieve low fouling protein detection in complex human serum.