Opto-electrochemical functionality of Ru(II)-reinforced graphene oxide nanosheets for immunosensing of dengue virus non-structural 1 protein

Transforming the structural and functional properties of carbon nanostructures are highly beneficial for healthcare diagnostics. This research demonstrates the functionalization o f opto-electrochemically active ruthenium bipyridine complex (Ru(II)) on the surface o f graphene oxide (GO), enabling a dual-functional immunoprobe for the detection o f non-structural 1 (NS1) protein, a dengue biomarker. Structural investigations reveals that Ru(II) has intermolecular bonding with functional groups o f GO. Ultraviolet photo-electron spectral readouts display the changes in the work function and ionization energy o f GO, supporting the functionalization of Ru(II). Bio-affinity layers o f protein-G (Pro-G) at GO-Ru(II) electrode interface promotes the localization o f monoclonal antibodies (mAb) selective for binding the epitopes of NS1 antigen. The chronoamperometric and fluorescence quenching-based immunoassays showed a linear response with a lowest detection limit o f 0.38 and 0.48 ng/mL, respectively. Under optimal condition, the developed immunosensor studied to have retained stability/sensitivity toward NS1 without impact from interferents. The dual functional immuno-bioprobe translated from GO-Ru(II) conjugated nanostructures offers new insights for further studies in on-site diagnosis.