Copper metabolism-responsive confined AIE gold nanocluster sensor enables rapid antimicrobial susceptibility testing

Antimicrobial resistance (AMR) poses a major threat to global public health, underscoring the urgent need for rapid phenotypic antimicrobial susceptibility testing (AST) to guide timely antibiotic therapy. With this in mind, we have designed a copper metabolism-responsive fluorescence sensing platform based on dendritic mesoporous silica-confined aggregation-induced emission (AIE) gold nanoclusters (DMSN@GSH-AuNCs, DA) for rapid bacterial detection and AST. In this sensing system, Cu 2 + effectively quenches the fluorescence of DA through coordination interactions, whereas bacteria can metabolically consume Cu 2+ to varying degrees, attenuating the quenching effect and generating a metabolism-dependent fluorescence signal. Compared with free AuNCs, the confined DA platform exhibits enhanced fluorescence quenching responsiveness, enabling more sensitive readout of bacterial metabolic activity. By coupling this response with antibiotic-induced metabolic inhibition, the platform allows discrimination between susceptible and resistant bacteria within 2 h. Notably, distinct signal responses were observed for representative Gram-negative and Gram-positive bacteria, indicating the broad applicability of this sensing strategy. In validation with 17 clinical Escherichia coli isolates, the method achieved high diagnostic performance, with area under the receiver operating characteristic curve (AUC) values of 0.958 and 0.950 for gentamicin and ciprofloxacin, respectively. These results demonstrate that the Cu 2+ -DA platform provides a rapid, sensitive, and operationally simple strategy for phenotypic AST and holds considerable promise for improving early antimicrobial stewardship.