Highly sensitive detection of three protein toxins via SERS-lateral flow immunoassay based on SiO₂@Au nanoparticles

We developed surface-enhanced Raman scattering-lateral flow immunoassay (SERS-LFIA) biosensor strips based on SiO₂@Au nanoparticles (NPs) for the specific and highly sensitive detection of ricin, staphylococcal enterotoxin B (SEB), and botulinum neurotoxin type A (BoNT/A). SiO₂@Au NPs were used to prepare SERS tags with useful properties, such as light weight, uniform particle size, good dispersion, and high SERS performance. The detection limit of the SERS-LFIA strips developed herein for ricin, SEB, and BoNT/A was 0.1, 0.05, and 0.1 ng/mL. Their sensitivity was 100-fold higher than that of colloidal gold-LFIA strips, and the same batch of strips had good repeatability. Moreover, the test was completed within 15 min, indicating that the strips are suitable for the rapid and on-site detection of the said toxins. The SERS-LFIA strips based on SiO₂@Au NPs developed herein for the detection of toxins are important to the prevention of bioterrorism attacks.