A microfluidic biosensor for online and sensitive detection of Salmonella typhimurium using fluorescence labeling and smartphone video processing

• Published in: Biosensors & bioelectronics Vol. 140; p. 111333
• Main Authors: Wang, Siyuan, Zheng, Lingyan, Cai, Gaozhe, Liu, Ning, Liao, Ming, Li, Yanbin, Zhang, Xibin, Lin, Jianhan
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 01-09-2019
• Subjects: Bacterial Load - instrumentation; Biosensing Techniques - instrumentation; Equipment Design; Fluorescence; Fluorescence labeling; Food Contamination - analysis; Food Microbiology; Food Safety; Humans; Immunomagnetic Separation; Lab-On-A-Chip Devices; Limit of Detection; Magnetic separation; Microfluidic biosensor; Mobile Applications; Salmonella Infections - microbiology; Salmonella typhimurium; Salmonella typhimurium - isolation & purification; Smartphone - instrumentation; Smartphone video processing; Microfluidic biosensor; Smartphone video processing; Magnetic separation; Salmonella typhimurium; Fluorescence labeling
• ISSN: 0956-5663; 1873-4235
• DOI: 10.1016/j.bios.2019.111333

Early screening of foodborne pathogens is a key to ensure food safety. In this study, we developed a microfluidic biosensor for online and sensitive detection of Salmonella based on immunomagnetic separation, fluorescence labeling and smartphone video processing. First, the immune magnetic nanoparticles were used to specifically separate and efficiently concentrate the target bacteria and the magnetic bacteria were formed. Then, the magnetic bacteria were labeled with the immune fluorescent microspheres and the fluorescent bacteria were formed. Finally, the fluorescent bacteria were continuously injected into the microfluidic chip on the smartphone-based fluorescent microscopic system, and the fluorescent spots were online counted using the smartphone App based on inter-frame difference algorithm to obtain the amount of the target bacteria. Under the optimal conditions, this proposed biosensor was able to quantitatively detect Salmonella typhimurium ranging from 1.4 × 102 to 1.4 × 106 CFU/mL, and its lower detection limit was 58 CFU/mL. This biosensor could be extended for detection of multiple foodborne pathogens using different fluorescent materials.
•Smartphone video processing was first time used to count fluorescent bacteria.•A facile microscopic system was developed to amplify fluorescent signals.•This biosensor was able to detect Salmonella as low as 58 CFU/mL in 2 h.•The mean recovery of Salmonella in spiked apple juice was ∼93%.