Rapid
and sensitive foodborne pathogen detection assay, which can
be applied in multiple fields, is essential to timely diagnosis. Herein,
we proposed a multisignal readout lateral flow immunoassay for Salmonella typhimurium (S. typhi) detection. The assay employs colorimetric-fluorescent-magnetic
nanospheres (CFMNs) as labels, which possess multifunctional target
separation and enrichment, multisignal readout, and two formats of
quantitation. The assay for S. typhi detection involves magnetic separation and chromatography. First,
the S. typhi were separated and enriched
from matrix by antibody labeled CFMNs, and then the S. typhi-containing suspension is added onto the
sample pad to flow up the test strip. The introduction of magnetic
separation enhances anti-interference ability and 10-fold sensitivity,
making the assay possible for practical application. The assay has
realized naked eye detection of 1.88 × 104 CFU/mL S. typhi, and 3.75 × 103 CFU/mL S. typhi can be detected with a magnetic assay reader,
which is 2–4 orders of magnitude lower than other label-based
LFIAs, with a quantitation range of 1.88 × 104 to
1.88 × 107 CFU/mL by measuring the fluorescence intensity
and magnetic signal. Moreover, the successful detection of S. typhi in complex matrix (tap water, milk, fetal
bovine serum, and whole blood) indicated its potential application
in real samples.