Electrochemical properties of Rubpy-reduced graphene oxide synergized by ultrasonication for label-free quercetin sensing

Tuning the interfacial properties of oxygenated graphene and reduced graphene oxide (rGO) with optical/electrochemically active molecules are highly useful for sensor studies. Herein, we demonstrate the ultrasonochemical mediated simultaneous reduction of oxygenated graphene and adsorption of ruthenium bipyridine complex (Rubpy) on the planes of rGO nanosheets. Different weight percentage ratio of Rubpy was decorated on the planes of rGO by simple alteration in the sonication parameters. Intercalation of Rubpy complex influences the electron cloud of inherent graphitic carbon network and intermolecular oxygenated functional moieties on the rGO matrix. Activation of C[dbnd]N network derived from bipyridine ligands of organometallic coordination compound, Rubpy, on the rGO planes enable an amplified electron mobility at the interface of electrode beneficial for electrocatalytic analysis. rGO-Rubpy modified electrode enabled direct electrochemical redox reaction of quercetin, exhibiting a linear detection range of 0.05–50 µM, with a lowest detection limit of 0.002 µM. Demonstrated label-free sensor platform display selectivity toward quercetin even in the presence of interferents and sensitivity in the real sample, promising for complementary analytical application.