Versatility of a localized surface plasmon resonance-based gold nanoparticle-alloyed quantum dot nanobiosensor for immunofluorescence detection of viruses

Flu infection, caused by the influenza virus, constitutes a serious threat to human lives worldwide. A rapid, sensitive and specific diagnosis is urgently needed for point-of-care treatment and to control the rapid spread of this disease. In this study, an ultrasensitive, rapid and specific localized surface plasmon resonance (LSPR)-induced immunofluorescence nanobiosensor has been developed for the influenza virus based on a gold nanoparticle (AuNP)-induced quantum dot (QD) fluorescence signal. Alloyed quaternary CdSeTeS QDs were synthesized via the hot-injection organometallic route and were subsequently capped with l-cysteine via a ligand exchange reaction. AuNPs were synthesized in HEPES buffer and thiolated with l-cysteine. The concept of the biosensor involves the conjugation of anti-neuraminidase (NA) antibody (anti-NA Ab) to thiolated AuNPs and the conjugation of anti-hemagglutinin (HA) antibody (anti-HA Ab) to alloyed quaternary l-cysteine-capped CdSeTeS QDs. Interaction of the antigens displaying on the surface of the influenza virus target with anti-NA Ab-conjugated AuNPs and anti-HA Ab-conjugated QDs induces an LSPR signal from adjacent AuNPs to trigger fluorescence-enhancement changes in the QDs in proportion to the concentration of the target virus. The detection limit for influenza H1N1 virus was 0.03 pg/mL in deionized water and 0.4 pg/mL in human serum; while, for the clinically isolated H3N2, the detection limit was 10 PFU/mL. The detection of influenza virus H1N1 was accomplished with high sensitivity. The versatility of the biosensor was demonstrated for the detection of clinically isolated influenza virus H3N2 and norovirus-like particles (NoV-LPs).