Biomimetic Mineralization Guided One-Pot Preparation of Gold Clusters Anchored Two-Dimensional MnO₂ Nanosheets for Fluorometric/Magnetic Bimodal Sensing

Abstract

A novel fluorometric/magnetic bimodal sensor is reported based on gold nanoclusters (Au NCs)-anchored two-dimensional (2D) MnO₂ nanosheets (Au NCs-MnO₂) that are synthesized through a one-pot biomimetic mineralization process. Bovine serum albumin (BSA) was used as the template to guide the formation and assembly of the Au NCs-MnO₂ under physiological conditions and without use of any strong oxidizing agent and toxic surfactants as well as organic solvent. The fluorescence of Au NCs was first quenched by MnO₂ nanosheets, while upon H₂O₂ introduction, the MnO₂ nanosheets can be sensitively and selectively reduced to Mn²⁺ with enhanced magnetic resonance (MR) signal and rapid recovery of Au NCs fluorescence simultaneously. This dual-modal strategy can overcome the weakness of a single-fluorescence detection mode. A linear range of 0.06-2 μM toward H₂O₂ was obtained for the fluorescence mode, whereas the MR mode also allowed detection of H₂O₂ at a concentration that ranged from 0.01 to 0.2 mM. Benefiting from the BSA molecule residual on the product surface, the as-prepared Au NCs-MnO₂ displays low cytotoxicity and good biocompatibility. Importantly, the successful application of Au NCs-MnO₂ for analysis of H₂O₂ in biological samples and cells indicates that the integration of Au NCs fluorescence with Mn²⁺ MR response provides a promising bimodal sensing platform for H₂O₂ in vivo monitoring.