Strong plasmon coupled gold nanoantennas with closed hot-spots enabled ultrasensitive lateral flow immunoassay of porcine epidemic diarrhea virus.

Porcine epidemic diarrhea virus (PEDV) is the etiological agent of porcine epidemic diarrhea (PED), which is an acute and devastating enteric disease in suckling piglets and shows cross-species transmission ability between pigs and humans as well. The accurate and timely detection of PEDV infection is essential for the control and prevention of viral transmission and outbreaks. Here, a strong plasmon coupled gold nanoantennas have been developed by Ag induced gold nanoparticles (AuNPs) assembly for surface-enhanced Raman scattering (SERS) integrated lateral flow immunoassay (LFIA) toward rapid and ultrasensitive determination of PEDV. The nanoantennas own sub-nm interparticle gaps, where showing a 1.26 ×10-fold improvement of the electromagnetic Raman enhancement (|E|/|E|) compared with the AuNPs. The sub-nm gaps are a novel kind of closed SERS "hot spot", which can block large size molecule like antibody and BSA from entering gaps and replacing Raman dyes inside. The established gold nanoantennas based SERS-LFIA exhibited high sensitivity with limits of detection (LOD) as low as 1.0 × 10 and 1.0 TCID/mL according to naked eye observation and SERS detection, respectively. The SERS signal was linearly related to the PEDV concentration in the range of 1.0 × 10 to 1.0 × 10° TCID/mL, with a linear equation of y = 3560 x+1843 (R = 0.99916). The established assay shows excellent specificity, reproducibility, and stability. The recovery rate of standardly added clinical samples was 94.91 %-102.07 %. Therefore, the gold nanoantennas based SERS-LFIA have great potential for the rapid and sensitive determination of PEDV, which will facilitate the disease diagnosis and prevention.