Nonfouling and ratiometric electrochemical detection of prostate specific antigen in whole serum

An efficient strategy for the establishment of ratiometric antifouling electrochemical biosensors was proposed based on the designed functional peptides and synthesized graphene oxide-nile blue A (GO-NB) nanocomposites. The peptide was designed to be of antifouling and recognizing functions, and the two branches of the peptide were labelled with the electrochemical probe ferrocene (Fc). The electrode was modified with synthesized GO-NB nanocomposites, and then followed by the electrodeposition of gold nanoparticles and the immobilization of Fc labelled peptides. NB was used as an internal probe to generate reference electrochemical signal, while the electrochemical sensing signal was generated by the Fc, and thus the ratiometric electrochemical sensing system was constructed. In this sensing system, the variances associated with electrochemical signal drift and the electrode-to-electrode difference, etc., can be calibrated with the reference signal of NB to generate stable ratiometric signal (Fc/NB). The electrochemical biosensor displayed a linear range from 5.0 pg mL^-1 to 100 ng mL^-1, with the limit of detection of 1.26 pg mL^-1. The integration of the ratiometric signal with the antifouling strategy can be readily expanded to the development of highly stable and accurate electrochemical sensing systems to be performed in complex biological systems.