Plasmonic/magnetic graphene-based magnetofluoro-immunosensing platform for virus detection

Binary nanoparticles (NPs)-modified graphene has been spotlighted due to their multi-functionalities and various applications. In this study, Au and iron oxide NPs-decorated graphene was prepared as dual-functional plasmomagnetic graphene (PMGRP), which plays roles in both magnetic carrier and a plasmonic substrate, and was utilized for a magnetofluoro-immunosensing (MFIS) platform. As proof of concept study of plasmonic substrate effect, fluoro-immunosensing (FIS) for detection of influenza virus was demonstrated by using anti-hemagglutinin antibody (HA Ab)-modified PMGRP and quantum dot (QD). In the presence of the virus, the sandwich structure between PMGRP and QD was formed through HA Ab-virus conjugation, and the fluorescence of QD was depended on the virus concentration. Influenza virus A (H1N1) in deionized water was successfully detected with a detection limit of 7.27 fg/ml. When human serum was mixed into virus as a model of a biological sample, the target virus-captured PMGRP was separated from impurity by magnetic force and the MFIS was performed with QD assistance. This result shows that virus was successfully separated and detected without any interruption of impurities, thus PMGRP-based MFIS platform is a potential and promising system for detection of virus in complex biological samples.