Syringe-driven biosensing of Salmonella typhimurium using nuclear track membrane filtration and nanozyme signal amplification

A syringe-driven colorimetric biosensor was constructed for simple detection of Salmonella typhimurium (S. ty) based on nuclear track membrane filtration and nanozyme signal amplification. First, immune [email protected] nanozymes (IGPNs) and large-volume sample in centrifugal tube were blow-mixed by push-and-pull of syringe. After S. ty-IGPN conjugates and free IGPNs was pulled into syringe, the syringe was connected with a uniform-size nuclear track membrane (NTM) and the mixture was pushed to flow through, resulting in selective trap of larger-size conjugates and effective remove of smaller-size IGPNs. Then, conjugates on the NTM were washed and H2O2-TMB was pulled to immerse the NTM. The catalysate was finally photographed and measured through smartphone App for detemination of S. ty. This biosensor enabled simple and in-field bacterial detection as low as 12 CFU/mL in 15 min. Compared with common sandwich-structured biosensors using paired antibodies, this biosensor with easier extension, lower cost and shorter time only required one antibody to functionalize nanozymes.