Versatile MOF@COF catalyzed and magnetically multivalent aptamer assisted biosensing platform for rapid and ultrasensitive dual-mode detection of multidrug-resistant bacteria

Given the frequent occurrence of multidrug-resistant bacteria (MDRB), which pose a severe threat towards public hygiene, it is important to construct facile and sensitive strategies for the detection of MDRB. We developed a fluorescent/colorimetric dual-mode biosensing platform for the analysis of MDRB by integrating the remarkable peroxidase-like activity of boric acid-decorated fluorescent framework hybrid (MOF@COF) nanozyme and enhanced bacterial affinity of DNA programmable multivalent aptamer scaffold. The efficiency and sensitivity of the proposed analysis approach were dramatically increased due to richer aptamers and high-performance MOF@COF nanozyme. Compared with commonly used single recognition methods, multivalent aptamers and bacteria-affinity boric acid groups on the nanozyme surface could identify multiple sites of MDRBs to improve site utilization for ultrasensitive biosensing. The platform realized selective detection of Acinetobacter baumannii (AB) and Pseudomonas aeruginosa (PA) in two modes with consistent results. In colorimetry and fluorescence modes, the linear ranges of AB were 102-108 and 10-108 CFU/mL with corresponding detection limits of 12 and 2 CFU/mL, and the linear ranges of PA were 102-108 and 10-108 CFU/mL with corresponding detection limits of 10 and 3 CFU/mL, respectively. More importantly, the biosensing platform could be applied for MDRB quantification in biological specimens, including human serum, cerebrospinal fluid, and urine with remarkable recoveries (96.8-105.0%) in both modes, indicating the bright prospect of the biosensing platform for MDRB determination in clinical diagnosis.