Development Of A UPT-based Immunochromatographic Assay For Detection Of Yersinia Pestis

Objective:By making fully use of Up-converting Phosphor Technology (UPT)-based biosensor and immunochromatographic assay (ICA), UPT-ICA strip has been developed for qualitative and quantitative on-site detection of Yersinia pestis rapidly and specifically. Moreover, the UPT-ICA strips can be easily adapted for detecting other microorganisms. Methods:In this assay, 400-nm up-converting phosphor (UCP) particles were used as the reporter. A sandwich immumoassay was employed using a polyclonal antibody against F1 antigen of Y. pestis immobilized on the nitrocellulose membrane and the anti-F1 monoclonal antibody conjugated to UCP particles. The signal detection of the strips was performed by the UPT-based biosensor that can provide a 980-nm IR laser to excite the phosphor particles, then collect the visible luminescences emitted by the UCPs and finally convert them to the voltage as signal. The ratio value (V_T / V_c) is directly proportional to the numbers of Y. pestis in the sample (CFU/ml) or the concentration of Fl antigen (ng/ml).Results:We observed a good linearity between the ratio and log CFU/ml of Y. pestis above the method's detection limit, which was approximately 10~4 CFU/ml, and a significant correlation(r=0.92406, p< 0.001) between the UPT-ICA and plate counting evaluated with these 51 lung tissue homogenates. 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 lng/ml of Fl antigen and the dynamic range of the assay was l~300ng/ml. Conclusion:The UPT-ICA system presented here takes less than 30min to perform from the sample treatment to the data analysis. It is well suitable for rapid qualitative and...