RNase H2 triggered visual loop-mediated isothermal amplification combining smartphone assisted all-in-one aptamer magnetic enrichment device for ultrasensitive culture-independent detection of Salmonella Typhimurium in chicken meat

Pre-enrichment cultural continues to remain time-consuming and labor-intensive in the detection of low-concentration bacteria in meat samples. Culture-independent detection method is urgently needed in POCT technology. In order to be able to proceed with culture-independent pre-enrichment for low-concentration pathogen detection, a RNase H2 enzyme triggered all-in-one device-based visual Loop-mediated Isothermal Amplification detection method was developed, combining with Salmonella Typhimurium specific Aptamer Magnetic Enrichment steps, termed as the AME-LAMP method. In order to better enable the AME-LAMP method to perform on-site culture-independent detection, a palm-held all-in-one device (PAD) was designed and manufactured. Further, a self-developed smart phone fluorescence analysis app could complete end-point detection, thus eliminating miscalculation. RNase H2 Enzyme triggered AME-LAMP method could detect Salmonella as low as 5.5 CFU/mL while conventional LAMP only detected 550 CFU/mL. By verifying the detection performance of AME-LAMP methods in chicken meat samples, AME-LAMP shows the potential to achieve ultrasensitive Salmonella detection by comparing with ISO isolation method and normal LAMP. With the assistance of smart phone-based PAD, it can be reliably applied for the on-site culture-independent detection of Salmonella Typhimurium.