Ultrasensitive detection of norovirus using a magnetofluoroimmunoassay based on synergic properties of gold/magnetic nanoparticle hybrid nanocomposites and quantum dots

Norovirus is the cause of the contagious disease gastroenteritis, and the infection is easy to spread because of the high infectivity of this virus. When the virus infects elderly people and young children, it may progress to severe disease. To prevent this hygienic threat, the development of highly sensitive and rapid detection methods is urgently needed. In this study, we developed a localized surface plasmon resonance (LSPR)-amplified magnetofluoroimmunoassay that can be used to detect norovirus even in biocomplex media without decreasing the fluorescence response. A multi-functional gold nanoparticle (AuNP) and magnetic nanoparticle (MNP) hybrid nanocomposite was synthesized. The AuNP/MNP hybrid nanocomposites and CdSeS quantum dots (QDs) were conjugated by the anti-norovirus genogroup II antibody (Ab). This hybrid nanocomposite made it possible to separate the target virus from impurities by a magnetic field and induced a high LSPR effect. Target virus was added to the Ab-conjugated AuNP/MNP composite and Ab-CdSeS QDs, and then Au/MNPs-Ab-virus-Ab-CdSeS QDs were separated by using an external magnetic field. The target norovirus-like particles can be detected in the range of 1 pg/ml to 5 ng/ml with a limit of detection (LOD) of 0.48 pg/ml in feces. This detection method was applied to clinical samples of feces containing norovirus from patients, and the LOD was 84 copies of RNA/ml without being affected by the impurities contained in the feces solution. This novel sensing system is suitable for norovirus detection in feces samples and for on-site detection.