Fluorescent-magnetic Janus nanorods for selective capture and rapid identification of foodborne bacteria

Abstract

A facile method for foodborne bacterial enrichment and direct identification from milk samples using Janus magnetic mesoporous silica nanoparticles (Janus M-MSNs) is reported. The fluorescent-magnetic nanorods are fabricated using the one-pot sol-gel process, followed by modification with Escherichia coli antibodies to form fluorescent Janus M-MSNs (Janus M-MSNs-Ab). The Janus M-MSNs-Ab combine the fast magnetic response capacity of the magnetic heads with the strong fluorescence and bacterial-targeting properties of the silica bodies, which results in selective capture and fluorescence identification of E. coli from milk samples containing mixed bacteria. After magnetic separation, complexes of the bacteria and nanoparticles are detected through direct matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS), which has a strong, anti-interference performance. Thus, the Janus M-MSNs-Ab synthesized in this study show great sensitivity and effectivity in foodborne bacterial capture and is a promising tool for rapid bacterial detection and investigation when combined with MALDI-TOF-MS.