Trypsin Electrochemical Biosensor Based on the Chiral Recognition Capability of Gold Nanoparticles/Bovine Serum Albumin

Trypsin (TRY) is an essential digestive enzyme, and its concentration level is regarded as a reliable indicator of pancreatic diseases. In this work, a highly sensitive and stable TRY electrochemical biosensor has been developed by taking advantage of the regulatable chiral recognition capability of gold nanoparticles/bovine serum albumin (AuNPs/BSA). Bovine serum albumin (BSA) is a protein with intrinsic chirality, which can be utilized to coat gold nanoparticles (AuNPs) through Au–S bonds and form AuNPs/BSA. Notably, the chiral recognition capability of AuNPs induced by d-Cysteine toward tyrosine (Tyr) enantiomers is opposite to that of BSA. For AuNPs/BSA, the chiral recognition capability is dominated by BSA adsorbed on the surface of AuNPs. By introducing varying concentrations of TRY, the structural integrity of BSA on the surface of AuNPs/BSA is gradually disrupted, resulting in a reversal of its chiral discrimination capability toward Tyr enantiomers, thereby enabling precise regulation of the chiral recognition capability of AuNPs/BSA relying on the specific hydrolysis of TRY. Therefore, the concentration of TRY can be sensitively detected by measuring the different recognition efficiencies of AuNPs/BSA/TRY toward Tyr enantiomers, namely, the peak current ratio of l-tyrosine to d-tyrosine (IL/ID) in differential pulse voltammetry. Additionally, the integration of dual electrochemical signals is conducive to enhancing the stability of the TRY detection results, manifesting the considerable application potential of the TRY electrochemical biosensor in biological analysis and medical diagnostics.