Automatic and sensitive detection of West Nile virus non-structural protein 1 with a portable SERS–LFIA detector

A portable surface-enhanced Raman scattering (SERS)–lateral flow immunoassay (LFIA) detector has been developed for the automatic and highly sensitive detection of West Nile virus (WNV) non-structural protein 1 (NS1) and actual WNV samples. Au@Ag nanoparticles (Au@Ag NPs) labeled with double-layer Raman molecules were used as SERS tags to prepare WNV-specific SERS–LFIA strips. On this platform, the WNV-specific antigen NS1 protein was quantitatively and sensitively detected. The detection limit for the WNV NS1 protein was 0.1 ng/mL, which was 100-fold more sensitive than visual signals. The detection limit for inactivated WNV virions was 0.2 × 10² copies/μL. The sensitivity of the SERS–LFIA detector was comparable to that of the fluorescence quantitative reverse transcription-polymerase chain reaction assay. The prepared SERS–LFIA strips exhibited high sensitivity and good specificity for WNV. Thus, the strips developed herein have clinical application value. Moreover, the portable SERS–LFIA detector enabled automatic and rapid detection of the SERS–LFIA strips. The platform established herein is expected to make a substantial contribution to the diagnosis and control of outbreaks of emerging infectious diseases, including WNV.