The integration of peptoid and phosphorothioate aptamer into electrochemical biosensors for the robust antifouling detection of prostate-specific antigen in human serum.

Electrochemical biosensors for biomarker detection in complex biological media often suffer from performance degradation. Two main causes are non-specific adsorption of biomolecules and enzymolysis of immobilized biomolecules. Consequently, the development of robust antifouling electrochemical biosensors represents an imperative research task. We herein report the design of an electrochemical antifouling biosensor for the detection of prostate-specific antigen (PSA) in complex biofluids based on the peptoid and phosphorothioate aptamer (PS-Apt). The peptoid was designed to be hydrophilic and neutral in total charge, and it was adopted as the antifouling material, while the PS-Apt was used as the biorecognition element. Both the peptoid and the PS-Apt resist degradation by natural enzymes in biofluids such as serum. This ensures the operational stability of the biosensor. The developed biosensor exhibited high sensitivity for PSA detection, with a broad linear range from 1.0 pg/mL to 0.1 μg/mL and a low limit of detection of 0.27 pg/mL. Furthermore, the biosensor demonstrated close agreement with the standard enzyme-linked immunosorbent assay for the quantification of PSA in clinical samples, without suffering from significant biofouling in human serum. This work presents a promising design strategy for robust antifouling biosensors aimed at biomarker monitoring in complex biofluids.