Core-shell Au@Ag NPs-based SERS-LFIA for the simultaneous quantitation of PEDV and PoRVA on site.

Porcine epidemic diarrhea virus (PEDV) and porcine group A rotavirus (PoRVA) are predominant pathogens responsible for infectious diarrhea in porcine. Co-infections of PEDV and PoRVA have become a common situation in porcine farms in recent years, which increases the severity of the diarrhea disease and makes the accurate diagnosis more difficult. Rapid quantitation of PEDV and PoRVA is of great significance for the guarantee of disease control. In this study, a 4-mercaptobenzoic acid (MBA) modified core-shell Au@Ag nanoparticles (Au@MBA@Ag NPs) based lateral flow immunochromatography (LFIA) with dual-signal modes of visual observation and surface-enhanced Raman scattering (SERS) signal analysis was developed for the rapid and sensitive detection of PEDV and PoRVA. The established SERS-LFIA was capable of simultaneous quantitation of PEDV and PoRVA in porcine fecal samples within 20 min, with visual limits of detection (LODs) of 6.25 × 10 TCID/mL and 7.42 × 10 copies/μL for PEDV and PoRVA, respectively. The LODs based on Raman signals were as low as 8.01 × 10 TCID/mL and 3.19 × 10 copies/μL for PEDV and PoRVA, respectively, which were more than two orders of magnitude lower than the conventional colloidal gold (AuNPs) based colorimetric immunochromatography. Additionally, the SERS-LFIA exhibited no cross-reactivity with other prevalent pathogens and was highly repeatability, with a coefficient of variation (CV) of less than 15 %. When detecting clinical samples, the overall compliance of the SERS-LFIA with RT-PCR results was 93.3 %. Thus, the developed SERS-LFIA showed great potential for field applications on the rapid diagnosis of PEDV and PoRVA infection.