Development and evaluation of an up-converting phosphor technology-based lateral flow assay for rapid detection of Francisella tularensis

Francisella tularensis is a potential biowarfare/bioterrorism agent and zoonotic pathogen that causes tularemia; thus, surveillance of F. tularensis and first-level emergency response using point-of-care testing (POCT) are essential. The UPT-LF POCT assay was established to quantitatively detect F. tularensis within 15 min and the sensitivity of the assay was 10 4 CFU · mL −1 (100 CFU/test). The linear quantitative range covered five orders of magnitude and the coefficients of variation were less than 10%. Except Shigella dysenteriae , UPT-LF showed excellent specificity to four strains that are also potential biowarfare/bioterrorism agents and 13 food-borne pathogenic strains. Samples with pH 2–13, high ion strengths (≥2 mol · L −1 solution of KCl and NaCl), high viscosities (≤50 mg · mL −1 PEG20000 or ≥20% glycerol) and high concentrations of biomacromolecules (≥400 mg · mL −1 bovine serum albumin or ≥80 mg · mL −1 casein) showed little influence on the assay. For practical utilization, the tolerance limits for seven powders and eight viscera were determined and operation errors of liquid measurement demonstrated a minor influence on the strip. Ftu-UPT-LF is a candidate POCT method because of its excellent sensitivity, specificity, and stability in complex samples, as well as low operation error.