Combination of dynamic magnetophoretic separation and stationary magnetic trap for highly sensitive and selective detection of Salmonella typhimurium in complex matrix

• Published in: Biosensors & bioelectronics Vol. 74; pp. 628 - 636
• Main Authors: Guo, Pei-Lin, Tang, Man, Hong, Shao-Li, Yu, Xu, Pang, Dai-Wen, Zhang, Zhi-Ling
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 15.12.2015
• Subjects: Bacterial Load - instrumentation; Biosensing Techniques - instrumentation; Combination; Complex Mixtures - analysis; Devices; Dynamical systems; Dynamics; Electrophoresis - instrumentation; Enrichment; Equipment Design; Equipment Failure Analysis; Food Analysis - instrumentation; Food Contamination - analysis; Food Microbiology - instrumentation; Immunomagnetic nanospheres (IMNs); Immunomagnetic Separation - instrumentation; Magnetic trap; Magnetophoretic separation; Milk; Pathogens; Reproducibility of Results; Salmonella; Salmonella typhimurium; Salmonella typhimurium (S. typhimurium); Salmonella typhimurium - isolation & purification; Sensitivity and Specificity; Separation; Magnetophoretic separation; Magnetic trap; Combination; Salmonella typhimurium (S. typhimurium); Immunomagnetic nanospheres (IMNs)
• ISSN: 0956-5663; 1873-4235
• DOI: 10.1016/j.bios.2015.07.019

Foodborne illnesses have always been a serious problem that threats public health, so it is necessary to develop a method that can detect the pathogens rapidly and sensitively. In this study, we designed a magnetic controlled microfluidic device which integrated the dynamic magnetophoretic separation and stationary magnetic trap together for sensitive and selective detection of Salmonella typhimurium (S. typhimurium). Coupled with immunomagnetic nanospheres (IMNs), this device could separate and enrich the target pathogens and realize the sensitive detection of target pathogens on chip. Based on the principle of sandwich immunoassays, the trapped target pathogens identified by streptavidin modified QDs (SA-QDs) were detected under an inverted fluorescence microscopy. A linear range was exhibited at the concentration from 1.0×104 to 1.0×106colony-forming units/mL (CFU/mL), the limit of detection (LOD) was as low as 5.4×103CFU/mL in milk (considering the sample volume, the absolute detection limit corresponded to 540CFU). Compared with the device with stationary magnetic trap alone, the integrated device enhanced anti-interference ability and increased detection sensitivity through dynamic magnetophoretic separation, and made the detection in complex samples more accurate. In addition, it had excellent specificity and good reproducibility. The developed system provides a rapid, sensitive and accurate approach to detect pathogens in practice samples. With the combination of the two parts, the sample can be purified before detection and the detection can be conducted on chip, so the device possesses stronger anti-interference ability and the detection results are more reliable.By controlling the flow rate of sample and buffer, the magnetophoretic separation unit can separate and enrich the target pathogens.The capture of target pathogens was conducted in the tube, we can remove the particulates in food samples before injected into the chip, avoiding the clog of channel.The on chip detection can save regents and reduce costs, and the continuous washing steps can greatly reduce the clean-up time and sample loss.