Graphene oxide-based immunobiosensor for ultrasensitive pathogen detection

In this study, we demonstrated a graphene oxide (GO)-based immunobiosensor system for pathogen detection using fluorescence quenching effect between GO and gold nanoparticles. The fluorescent GO sheets was deposited on an amino-modified glass surface by electrostatic force, and the carboxylate functional group on the GO surface was used to covalently conjugate rotavirus-antibodies to be linked on the surface. The target pathogen, rotavirus, was then incubated and bound by a specific antigen-antibody interaction. Finally, an engineered gold nanoparticle-labeled antibody probe was attached to the captured target cell which complexes enable gold nanoparticles to be close to the GO surface, thereby resulting in the quenching of GO fluorescence signal to identify the pathogen. The more Au NPs lead to drastic fluorescence reduction of GO, allowing a sensitive rotavirus detection, and the maximized GO quenching efficiency is obtained up to 85% at 10⁵ pfu/mL. The unique fluorescence emission property and facile fabrication method of GO sheets from cheap graphite resources provide great potential of GO to be applied for biosensors as well as molecular diagnostics as a novel fluorescence tag.