Peptide-activated gold nanoparticles for selective visual sensing of virus

In this study, we report peptide–gold nanoparticles (AuNP)-based visual sensor for viruses. Citrate-stabilized AuNP (20 ± 1.9 nm) were functionalized with strong sulfur–gold interface using cysteinylated virus-specific peptide. Peptide–Cys–AuNP formed complexes with the viruses which made them to aggregate. The aggregation can be observed with naked eye and also with UV–Vis spectrophotometer as a color change from bright red to purple. The test allows for fast and selective detection of specific viruses. Spectroscopic measurements showed high linear correlation (R ² = 0.995) between the changes in optical density ratio (OD₆₁₀/OD₅₂₀) with the different concentrations of virus. The new method was compared with the hemagglutinating (HA) test for Newcastle disease virus (NDV). The results indicated that peptide–Cys–AuNP was more sensitive and can visually detect minimum number of virus particles present in the biological samples. The limit of detection for the NDV was 0.125 HA units of the virus. The method allows for selective detection and quantification of the NDV, and requires no isolation of viral RNA and PCR experiments. This strategy may be utilized for detection of other important human and animal viral pathogens.