Single atom-bridged Au nanozymes boost glucose oxidase-like activity in acidic media

Abstract

Au nanozymes hold great promise as glucose oxidase (GOx) mimics; however, their catalytic activity and pH dependence remain significant challenges. Herein, we synthesize Fe single atom (SA)-bridged Au nanozymes (Au NPs /FeNC) with dual catalytic sites, achieving a 3.7-fold enhancement in GOx-like activity under acidic media compared to Au NPs /NC. Experimental and theoretical analyses reveal that Au-to-Fe charge transfer facilitates O 2 adsorption at Fe sites, synergistically boosting glucose oxidation. Unlike previously reported Au-H intermediates formed under alkaline conditions, in situ monitoring identifies the formation of Au-Fe-OO intermediates in Au NPs /FeNC, which facilitate the dehydrogenation of glucose and enhance the catalytic efficiency in acidic environments. Benefiting from optimal GOx-and peroxidase-like activities at pH 4.0, an Au NPs /FeNC-based glucose cascade system is constructed with exceptional properties. As a proof of concept, this system is integrated into a portable, gel-based sensor for real-time and visual determination of organophosphorus pesticides. This study provides valuable insights into the rational design of high-performance nanozymes featuring dual catalytic sites for advanced sensing applications.