Peptide-engineered catalytic and antifouling interface for reliable electrochemical analysis in undiluted biological samples

Catalytic signal amplification can improve the sensitivity of electrochemical analysis, but its analytical reliability is frequently compromised in complex biological matrices because nonspecific adsorption hinders mass transport, blocks electron-transfer pathways, and attenuates signal output. Integrating signal amplification with effective antifouling regulation within a single analytical interface is therefore important for maintaining quantitative performance in untreated biological samples. Here, we address the challenge of reconciling catalytic amplification with matrix tolerance for reliable electrochemical analysis in undiluted biological samples.

A peptide-engineered analytical interface was constructed by integrating a peptide-templated Au/PNF nanozyme with an antifouling and MMP-2-responsive peptide layer. Self-assembled hIAPP_20-29 nanofibers directed Au nanoparticle nucleation to generate a peroxidase-like nanozyme capable of H₂O₂-dependent electrochemical signal amplification. The multifunctional peptide suppressed nonspecific adsorption while preserving target accessibility. The resulting platform enabled MMP-2 determination over 0.5-100 ng mL^-1 with a calculated detection limit of 37 pg mL^-1. In undiluted human serum, the antifouling interface provided improved recovery and precision compared with the corresponding non-antifouling interface. It also markedly reduced matrix-induced signal suppression after exposure to FBS and whole blood, demonstrating improved matrix tolerance and more stable analytical performance under severe biological interference.

This work integrates catalytic amplification and antifouling regulation within a peptide-engineered electrochemical interface and experimentally distinguishes catalytic, interfacial, and matrix-tolerance contributions. The strategy maintains analytical reliability in undiluted serum while preserving catalytic signal generation, providing a general design concept for electrochemical analysis in complex biological matrices where signal amplification alone is insufficient.