Capture, sterilization and determination platform of foodborne pathogen based on Halbach ring-mediated magnetic filter

Herein, an ingenious Halbach ring-mediated magnetic filter (HRMF) for capture, sterilization, and detection of foodborne pathogenic bacteria is developed. A composite material with magnetic nanoparticles (MNP) as the core and coated with polydopamine (PDA) and polyethylenimine (PEI) is synthesized, namely MNP@PDA@PEI. Under a Halbach ring, MNP@PDA@PEI can form chains to generate HRMF. Due to the positively charged of PEI, the HRMF could capture the negatively charged bacteria from solution via electrostatic adsorption. Within the HRMF, sterilization performance could be achieved due to the photothermal effect of MNP@PDA@PEI after 5 min of near-infrared light irradiation. More importantly, the number of bacteria could be calculated by bioluminescence method for measuring ATP, which are released from bacteria after photothermal sterilization. Listeria monocytogenes is chosen as a typical bacterium to evaluate the function of HRMF. The time of whole process has been greatly reduced to 38 min. The capture efficiency is 98.63%, and sterilization rate can achieve 99.96% in real samples. The limit of detection is 10.04 CFU/mL, representing a 10-fold decrease compared with bioluminescence method alone. The proposed platform might open a new way for on-site real-time detection of foodborne pathogens, and hold potential to nondestructive sterilization in the food processing industry.