Functionalized magnetic nanoparticles enrichment and nanoelectrospray ionization coupled with a miniature mass spectrometer: A broad-spectrum rapid bacterial discrimination platform

Pathogenic infections pose a major global health risk due to their high morbidity and mortality. Rapid and accurate bacterial discrimination is currently an emerging trend in the fields of food safety, medical diagnostics, and environmental monitoring. This study introduces a comprehensive platform for the rapid and broadspectrum identification of pathogenic bacteria, integrating bacteria enrichment and online lysis, nanoelectrospray ionization (nanoESI), miniature mass spectrometry (MS) analysis, and machine learning algorithms. Capture efficiencies exceeding 95 % for various bacterial species were achieved through interactions between polyethyleneimine-functionalized magnetic nanoparticles (PEI-MNPs) and bacteria following a 10-minute incubation period. Subsequently, the bacteria similar to MNPs complexes were subjected to online lysis via a simple ultrasound-assisted electrospray solvent cracking process to release bacterial extracts. Using nanoESI and miniature MS analysis, fingerprints providing comprehensive characterization of bacterial signature information were obtained rapidly. By employing a kNN machine learning model, the platform successfully identified different bacteria species and E. coli strains with 100 % overall identification accuracy within 15 minutes. Meanwhile, E. coli and S. aureus served as model bacteria for the quantitative evaluation of the platform, which could successfully distinguish concentrations of E. coli and S. aureus at 10(4) and 10(5) cfu/mL, respectively, and their mixture samples at 10(6) cfu/mL. Its practicality was further validated through the accurate identification of bacteria in real samples, demonstrating promising potential for real-time bacterial contamination monitoring in on-site environments.