Copolymerization of zwitterionic sulfobetaine and hydrophobic acrylamide based antifouling electrochemical biosensors for detection of CA125 in clinical serum samples

It is crucial to construct antifouling electrochemical biosensors with long-term stability and high sensitivity for the detection of biomarkers in complex biological environments to prevent the unspecific adsorption of proteins and other biomolecules. Herein, a glassy carbon electrode electropolymerization with polyaniline (PANI/GCE) was further modified with a copolymerization (PSN) of zwitterionic sulfobetaine methacrylate (SBMA) and hydrophobic N-isopropyl acrylamide (NIPAM) by simple hydrophobic interaction to construct an antifouling biosensor. PSN forms a stable self-assembled monolayer on the PANI/GCE surface and exhibits good antifouling performance in serum due to the advantages of hydrophobic anchoring and the antifouling performance of zwitterionic polymers. Ascribe to the large specific surface area and excellent conductivity, the present biosensor can detect CA125 in undiluted samples in the range of 0.01-1000 U mL-1 with a limit of detection of 2.7 mU mL-1 (3 sigma/k). Both with good biocompatibility and biological stability, PSN modified sensing surface realizes a long-term antifouling for 15 days in a buffer solution. The present work provides a simple strategy for the direct analysis of CA125 in human serum without a complicated construction of biosensors, indicating the potential application in clinical diagnosis.