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

Although Au nanozymes hold great promise as glucose oxidase (GOx) mimics, their catalytic activity and pH dependence remain significant challenges. Herein, we synthesize Fe single atom 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 charge transfer from Au to Fe single atom facilitates O₂ 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.