An aptamer-based "Gate-lock-key" strategy for metal-organic framework nanozyme-catalyzed colorimetric detection of multidrug-resistant bacteria.

An aptamer-gated metal-organic framework-based biosensing platform for highly sensitive detection of multidrug-resistant bacteria (MDRB) has been developed. This biosensing platform utilizes aptamers as specific "gated" switches, which are integrated with the UiO-66-NH₂ MOFs to construct a "gated" sensing system loaded with 3,3',5,5'-tetramethylbenzidine (TMB). The entry of target bacteria induces specific dissociation of sDNA/Apt, forming an aptamer-bacteria complex on the UiO-66-NH₂ surface while releasing TMB into the solution. Subsequently, the PCN-224-Mn nanozyme catalyzes the oxidation of TMB, generating a colorimetric signal. This biosensing platform demonstrates a broad linear range for detecting New Delhi metallo-β-lactamase-1 Klebsiella pneumoniae (NDM-1 KP) and multidrug-resistant Acinetobacter baumannii (MDR-AB), achieving ultra-high sensitivity with detection limits of 5 CFU/mL and 7 CFU/mL, respectively. The practical performance of this biosensing platform was evaluated through spiked recovery experiments. Its excellent recovery demonstrates that the method maintains high reliability and stability even when applied to complex real-world samples, providing an effective technical solution for addressing challenges in microbial detection in practical scenarios.