Nanogapped Fe<sub>3</sub>O<sub>4</sub>@Au Surface-Enhanced Raman Scattering Tags for the Multiplex Detection of Bacteria on an Immunochromatographic Strip
Jiaxuan Li, Ting Wu, Chaoguang Wang, Chaoguang Wang, Jian Tu, Xiangjun Song, Ying Shao, Chongwen Wang, Chongwen Wang, Kezong Qi, Rui Xiao
Abstract
Herein, we present an ultrasensitive surface-enhanced Raman scattering (SERS)-based immunochromatographic assay (ICA) for the multiplex detection of foodborne bacteria in food samples by using nanogapped Fe3O4@Au (Mag@Au) as multifunctional SERS tags. The Mag@Au tags with multiple surface hotspots were integrated into the ICA system for the first time to provide a superior SERS signal for ICA analysis, high stability for complex samples, and magnetic enrichment ability for target pathogens. Visible test lines were successfully introduced by mixing bovine serum albumin (BSA)-coated gold nanoparticles (Au@BSA) with detection antibodies, which can facilitate the accurate positioning of test zones for quantitative SERS analysis. The magnetic SERS-ICA can achieve simultaneous and quantitative detection of Salmonella typhimurium and Staphylococcus aureus in 30 min with low limits of detection of 12 and 9 cells mL–1, respectively. The proposed method further demonstrated good stability and accuracy in various food samples and thus possesses great potential for on-site and sensitive monitoring of bacteria.