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

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.