Au@4-MBA@Ag NPs labeled SERS lateral flow immunoassay for ultrasensitive and quantitative detection of Salmonella enteritidis

Salmonella enteritidis (S. enteritidis) is a common zoonotic pathogen which can cause acute gastroenteritis characterized with fever, diarrhea and vomiting, posing a serious threat to public health. Rapid and accurate detection of S. enteritidis is in great demand for food safety and timely diseases treatment. In the present study, a surface-enhanced Raman scattering lateral flow immunoassay sensor (SERS-LFIA) was developed for the rapid, ultrasensitive and quantitative detection of S. enteritidis using Au-core Ag-shell nanoparticles sandwiched with Raman molecules. S. enteritidis could be quantitatively detected by SERS-LFIA at concentrations ranging from 1 x 103 to 1 x 107 CFU mL-1, with limits of detection (LOD) of 1 x 105 CFU mL-1 and 1.36 x 102 CFU mL-1 based on naked eye observation and SERS signal analysis, respectively. No cross-reaction was observed from other serotypes of Salmonella and other common pathogens. The coefficient of variation for both the intra- and interbatch repetitive tests were less than 10%. The recovery rates of spiking feces and eggshells were between 94.8% and 104.7%. Thus, this SERS-LFIA is able to quantitatively detect S. enteritidis in 20 min with high sensitivity, specificity, repeatability, and could be a promising method for the early detection of S. enteritidis in various clinical samples.