To alleviate side reactions identified in an N-propargyl-rhodamine lactam sensing system, we devised the novel reaction-based sensing scheme for gold species based on the alkynophilicity. A fluorescein (2-ethynyl) benzoate underwent Au (III)-promoted ester hydrolysis selectively over other metal ions with high sensitivity, which accompanies a turn- on fluorescence change in pH 7.4 HEPES buffer. The work offers a versatile reactive ...