Nanogapped Fe₃O₄@Au Surface-Enhanced Raman Scattering Tags for the Multiplex Detection of Bacteria on an Immunochromatographic Strip

Abstract

Herein, we present an ultrasensitive surfaceenhanced Raman scattering (SERS)-based immunochromatographic assay (ICA) for the multiplex detection of foodborne bacteria in food samples by using nanogapped Fe 3 O 4 @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.

Introduction of a multilayered fluorescent nanofilm into lateral flow immunoassay for ultrasensitive detection of Salmonella typhimurium in food samples

“…Our proposed GO/DQD-based LFIA is essentially an immunoassay that is based on antibody–antigen interactions. In accordance with previous reports, 39,40 we applied an effective anti- S. typhi monoclonal antibody (Abcam, catalog no. ab8274) to construct the GO/DQD-LFIA method for S. typhi detection.…”

Universal and ultrasensitive detection of foodborne bacteria on a lateral flow assay strip by using wheat germ agglutinin-modified magnetic SERS nanotags

“…The mixture of Fe 3 O 4 -20/3 nm Au seed NPs and DTNB was vigorously sonicated for 1 h to form DTNB-modified Fe 3 O 4 –Au seed NPs. 38 Afterward, 1 mL of Fe 3 O 4 –Au seed/DTNB was added into 40 mL of deionized water containing 2 mg mL −1 PVP, 0.5 mg mL −1 hydroxylamine hydrochloride, and 200 μL of 1% HAuCl 4 ·4H 2 O. The mixture was sonicated vigorously for 5 min to form the nanogapped Au shell outside of the Fe 3 O 4 core.…”

Nanomaterial interfaces designed with different biorecognition elements for biosensing of key foodborne pathogens

“…Li, Wi et al. (2022), reported a high‐powered SERS‐ICA (immunochromatographic assay) method using multifunctional gold‐coated Fe 3 O 4 magnetic (Mag@Au) tags to achieve the sensitive (12 and 9 cells mL −1 ), rapid (30 min) and stable detection of both S. typhimurium and S. aureus in actual food samples. The use of Mag@Au tag in biosensor design has been reported as not only enhanced the SERS activity but also enabled the multiplex detection of ICA method, as well as the capturing of target bacteria, thereby ensuring high stability of the method in complex untreated samples.…”