Highly sensitive and rapid technology of surface enhanced Raman scattering (SERS) was applied to create aptasensors for influenza virus detection. SERS achieves 10^7 times signal amplification, yielding excellent sensitivity, whereas aptamers to hemagglutinin provide specific recognition of the influenza virus. Aptamer RHA0385 was demonstrated to have essentially broad strain-specificity toward both recombinant hemagglutinins and the whole viruses. To achieve high sensitivity, a sandwich of primary aptamers, influenza virus and secondary aptamers was assembled. Primary aptamers were attached to metal particles of a SERS substrate, and influenza viruses were captured and bound with secondary aptamers labeled with Raman-active molecules. The signal was affected by the concentration of both primary and secondary aptamers. The limit of detection was as low as 10^(-4) hemagglutination units per probe as tested for the H3N2 virus (A/England/42/72). Aptamerbased sensors provided recognition of various influenza viral strains, including H1, H3, and H5 hemagglutinin subtypes. Therefore, the aptasensors could be applied for fast and low-cost strain-independent determination of influenza viruses.
