Development Of A UPT-based Immunochromatographic Assay For Detection Of Vibrio Cholerae

Objective By making fully use of Up-Converting Phosphor Technology (UPT) and immunochromatographic assay (ICA), UPT-ICA strip has been distinguished between O1 and O139 Vibrio cholerae. Meanwhile, UPT-ICA strip has been developed for qualitative and quantitative on-site detection of Vibrio cholerae rapidly and specifically. Moreover, the UPT-ICA strips can be easily adapted for detecting other microorganisms.Methods In this assay, it used 400nm Up-Converting Phosphor (UCP) particles as the reporter and a sandwich immunoassay using the polyclonal antibodies immobilied on the nitrocellulose membrane and conjugated to UCP particles to prepara the immunochromatographic test trip. The UPT-based biosensor performed signal detection of the strips and can provide a 980nm IR-laser to excite the UCPs, then collect the visible luminescence emitted by the phosphor particles and finally convert them to the voltage as signal. The ratio value (VT/VC) is directly proportional to the numbers of Vibrio cholerae in the sample (CFU/ml).Results The UPT-ICA system has been distinguished between O1 and O139 Vibrio cholerae and showed good sensitivity and specificity and a significant correlation between the UPT-ICA and plate counting evaluated. We observed a good linearity between the ratio and log CFU/ml of O1 Vibrio cholerae above the method's detection limit, which was approximately 1.69×104CFU/ml, and the dynamic range of the assay was 105 CFU/ml～108 CFU/ml. The precision of the intra-and inter-assay is below 15%(coefficient of variation, CV). Cross-reactivity with related Gram-negative enteric bacteria is not found. Moreover, The minimal detectable concentration was 1.69×104CFU/ml of O139 Vibrio cholerae and the dynamic range of the assay was 105 CFU/ml～108 CFU/ml. Conclusion The UPT-ICA system presented here takes less than 30min to perform from the sample treatment to the data analysis. It can distinguish between 01 and 0139 Vibrio cholerae and can be used for rapid qualitative and quantitative on-site detection of 01 and 0139 Vibrio cholerae. Furthermore,it can be carried out nearly anywhere by no-technical personnel. Therefore, the UPT-ICA system is well suitable for field monitoring and epidemic of Vibrio cholera.