Nano Research & Applications

Magnetic micro-particle immune separation combined with enzyme linked immunosorbent assay for quick detection of Salmonella typhimurium in raw eggs

An immunomagnetic separation (IMS) method was developed for separating Salmonella typhimurium bacteria from large-volume samples of raw eggs. An egg was homogenized with a blender. The homogenized egg material was diluted with DI water to make a 200 mL sample mixture. Anti-Salmonella typhimurium antibody coated magnetic micro particles (MMP) were used to trap the Salmonella bacteria in the sample mixture. The Salmonella-trapped MMP were separated from the egg sample matrices by using a large magnet. An enzyme-linked immunosorbent assay method was adopted and revised for detecting the bacteria trapped onto the MMP. A horseradish peroxidase (HRP) labeled anti-Salmonella typhimurium antibody was used to label the trapped bacteria, and a SureblueTM solution was used as a substrate. The color compound resulted from HRP-catalyzed reaction was detected with UV/Vis absorption spectrometry using a 1 cm sample cell. This simple method can detect 1.4*107 Salmonella typhimurium cells in one raw egg (7.0*104 Salmonella typhimurium cells/mL in a sample mixture) without any preenrichment. The results presented in this paper demonstrate the feasibility of using IMS for separating bacteria from large volume complex samples, which could be adopted for detecting bacteria in other type samples in food safety inspection.

Author(s):

Cole Guyer, Shiquan Tao and Maya Alex

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