Ir–S Bonding Is Superior to Au–S Bonding for the Construction of Robust Antifouling Biosensors through Self-Assembly

Abstract

The formation of Au–S bonding is commonly used for the fabrication of biosensors through self-assembly, but the stability of the Au–S bonding is not always satisfying in complex biological systems, as they contain biothiols like glutathione that may displace the self-assembled thiolated molecules. To address this issue, we explored the utilization of iridium–thiol interaction to form highly stable Ir–S bonding through self-assembly, and an electrochemical biosensor was developed by immobilizing antifouling thiol-peptides onto an electrode modified with Ir nanoparticles. The Ir–S bond was verified to be more robust than the Au–S bond, which ensured effective peptide immobilization and reduced displacement by biothiols. Additionally, we integrated functionalized peptides specifically designed for murine double minute 2 (MDM2) biological assays, resulting in a highly stable and sensitive platform for quantifying MDM2 in biological matrices. The explored Ir–S binding offers a new avenue for the self-assembly of thiolated molecules to develop ultrarobust biosensors and bioelectronics with enhanced reliability in complex biological environments.