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

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.