Analysis of antibiotic-resistant bacteria and β-lactamase activity using multifunctional mesoporous silica nanoparticles and mass spectrometry Yen-Peng Ho, Yu-Shuan Tsai, Yun-Ting Fu Department of Chemistry, National Dong Hwa University, Hualien, Taiwan The emergence of antibiotic-resistant bacteria has become a major concern to the public health, which is due to the misuse and over usage of antibiotics. Conventional methods such as antimicrobial susceptibility test have been used to identify antibiotic resistance of bacteria. The major drawback of these methods is time-consuming. We propose a sensitive/rapid and multi-target detection method for the determination of b-lactamase activity of antibiotic-resistant bacteria. A micro-reactor was synthesized based on a pH-sensitive fluorescent dye-doped mesoporous silica nanoparticle encapsulated with antibiotics as a substrate. When penicillin G, the antibiotics, was hydrolysed by β-lactamase present in antibiotic-resistant bacteria and converted into penicilloic acid, the acidic environment results in fluorescence quenching of the dye. 1 The dye-doped mesoporous nanoparticles not only stabilized the substrate but also acted as a microreactor, which was new approach. 2 The proposed method may detect the presence of b-lactamases of clinically relevant samples in less than 1 hour. Moreover, the detection limit of b-lactamase activity was as low as 5×10 -4 U/mL. Further, the method was coupled with mass spectrometry 3 to detect pathogens with various antibiotics resistance. The reactor was loaded with β-lactam antibiotics-penicillin G and cephalosporin antibiotics-ceftazidime as substrates. When penicillin G and ceftazidime were hydrolyzed by β-lactamase present in bacteria, the hydrolysis products were detected using mass spectrometry. This method may detect the β-lactamase activity as low as 2.5 × 10 - 5 U/mL within two hours. References 1. Peng, L.; Xiao, L.; Ding, Y.; Xiang, Y.; Tong, A. Journal of Materials Chemistry B 2018 , 6 , 3922-3926. 2. Tummala, S.; Hunag, W.-A.; Wu, B.-H.; Chang, K.-C.; Ho, Y.-P. ChemistryOpen , 2020 , 9 (10), 1074-1081. 3. Junza, A.; Montané, A.; Barbosa, J.; Minguillón, C.; Barrón, D. Journal of Chromatography A 2014, 1368 , 89-99.
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