Optoelectronic fowl adenovirus detection based on local electric field enhancement on graphene quantum dots and gold nanobundle hybrid.

An optoelectronic sensor is a rapid diagnostic tool that allows for an accurate, reliable, field-portable, low-cost device for practical applications. In this study, template-free In situ gold nanobundles (Au NBs) were fabricated on an electrode for optoelectronic sensing of fowl adenoviruses (FAdVs). Au NB film was fabricated on carbon electrodes working area using L(+) ascorbic acid, gold chroloauric acid and poly-l-lysine (PLL) through modified layer-by-layer (LbL) method. A scanning electron microscopic (SEM) image of the Au NBs revealed a NB-shaped Au structure with many kinks on its surface, which allow local electric field enhancement through light-matter interaction with graphene quantum dots (GQDs). Here, GQDs were synthesized through an autoclave-assisted method. Characterization experiments revealed blue-emissive, well-dispersed GQDs that were 2-3nm in size with the fluorescence emission peak of GQDs located at 405nm. Both Au NBs and GQDs were conjugated with target FAdVs specific antibodies that bring them close to each other with the addition of target FAdVs through antibody-antigen interaction. At close proximity, light-matter interaction between Au NBs and QDs produces a local electric signal enhancement under Ultraviolet-visible (UV-visible) light irradiation that allows the detection of very low concentrations of target virus even in complex biological media. A proposed optoelectronic sensor showed a linear relationship between the target FAdVs and the electric signal up to 10 Plaque forming unit (PFU)/mL with a limit of detection (LOD) of 8.75 PFU/mL. The proposed sensing strategy was 100 times more sensitive than conventional ELISA method.