Ultrasensitive Detection of Multidrug-Resistant Bacteria Based on Boric Acid-Functionalized Fluorescent MOF@COF

The widespread use of antibiotics has made multidrug-resistant bacteria (MDRB) one of the greatest threats toward global health. Current conventional microbial detection methods are usually time-consuming, labor-intensive, expensive, and unable to detect low concentrations of bacteria, which cause great difficulties in clinical diagnosis and treatment. Herein, we constructed a versatile biosensing platform on the basis of boric acid-functionalized porous framework composites (MOF@COF-BA), which were able to realize highly efficient and sensitive label-free MDRB detection via fluorescence. In this design, MDRB were captured using aptamer-coated nanoparticles and the fluorescent probe MOF@COF-BA was tightly anchored onto the surface of MDRB due to interactions between boric acid groups and glycolipids on bacteria cells. Benefitting from the remarkable fluorescence performance of MOF@COF-BA, rapid and specific detection of MDRB, such as methicillin-resistant Staphylococcus aureus (MRSA) and Acinetobacter baumannii (AB), was realized with a detection range of 20-10⁸ CFU/mL (for both) and limits of detection of 7 CFU/mL (MRSA) and 5 CFU/mL (AB). The feasibility of using the developed platform to selectively detect MRSA and AB from complex urine, human serum, and cerebrospinal fluid samples was also demonstrated. This work provides a promising strategy for accurate MDRB diagnosis, avoiding serious infection using rational antibiotic therapy.

Boric Acid Functional Fluorescent Covalent-Organic Framework for Sensitive and Selective Visualization of CH3Hg. ACS Appl Mater Interfaces 2023;15:9524-9532. [PMID: 36757912 DOI: 10.1021/acsami.2c23302]

Methylmercury (CH3Hg+) recognition remains a challenging and imperative task due to its high toxicity and wide existence in the ecosystem. Herein, a novel fluorescent covalent-organic framework containing a boric acid functional group (COF-BA) was prepared by a postmodification strategy for CH3Hg+ detection. COF-BA served as a sensing platform for CH3Hg+ with fluorescence static quenching accompanied by fluorescence color changing from intense blue to colorless, and the detection limit was determined as 1.68 μM in a relatively narrow concentration range. COF-BA also exhibited superior selectivity toward CH3Hg+ detection. Furthermore, the spiked and recovery test in real water samples showed its efficient detection practicality. The detection mechanism of COF-BA toward CH3Hg+ was investigated. The recognitive boric acid group in COF-BA was first replaced by CH3Hg+. Then, the quinoline structure that served to limit the rotation of the imine bond was disrupted, leading to dramatic fluorescence quenching. The boric acid functional COF fluorescent probe can be a promising sensing platform for the detection of methylmercury and also provides new ideas for the construction of new fluorescent COF materials.