Design a novel electrocchemical sensor based on glassy carbon electrode modified with titania nanoparticles, copper oxide and reduced graphen oxide ternary nanocomposites for the electrocatalytic determination of ascorbic acid

An important factor in the fabrication of a sensitive electrochemical sensor is preparing an efficient platform to achieve a stableelectrochemical response. Among various type of the electrodes, the glassy carbon electrode (GCE) has received considerableinterest owing to their low residual current, wide potential range, ease of fabrication and simple surface regeneration. In addition,using of nanostructures has attracted huge interest in modifying the activity of electrochemical sensors [1]. Reduced graphene oxide(rGO) has become a highly expanding area in modern research due to many fantastic characteristics such as strong mechanicalstrength, large surface area, great conductivity and electrocatalytic properties [1]. Combination of the rGO with other nanomaterials such as magnetic NPs, metal oxide and etc., with inherent unique properties can result to facilitate electron transferbetween redox systems and bulk-electrode materials. Different kind of nanostructures have been used for this purpose, recentlyTiO2 nanoparticles by having good dispersing properties, large surface area, good biocompatibility have been widely applied foreither electrochemical biosensor fabrication or mechanistic studies [2]. Combination of the TiO2NPs, copper (II) oxide and reducedgraphene oxide and production of a nanocomposites would be a suitable choice to form an efficient platform in the generation of aGCE as a sensitive sensor. The main aim of this work is to present a new sensor based on TiO2@CuO-rGO modified glassy carbonelectrode (TiO2NP@CuO-rGO/GCE) for sensitive AA determination. The properties and characterization of this sensor werestudied using some common techniques and practical application of the sensor was evaluated in human blood serum samples as thereal sample.In the present work, titania nanoparticles, copper oxide and reduced graphen oxide ternary nanocomposite (TiO2NP@CuO-rGO)modified glassy carbon electrode (GCE) has been used for sensitive determination of ascorbic acid (AA). The modified glassycarbon electrode was characterized over the successive modification steps, by XRD, FT-IR spectroscopy, cyclic voltammetry (CV),electrochemical impedance spectroscopy (EIS) and scanning electron microscope imaging (SEM). Electrochemical determinationswere carried out using differential pulse voltammetry (DPV), and amount of ternary nanocomposite (TiO2NP@CuO-rGO), effectof pH and potential scan rate were optimized. The electrochemical properties of the AA was monitored by performing cyclicvoltammetry (CV) experiments. The CVs and DPVs showed one oxidation peak during the anodic potential scan. Theelectrochemical determination by differential pulse voltammetry provided linear concentration range from 10.0 pmol L−1 to 10.0μmol L−1, with detection limit of 3.0 pmol L−1. The TiO2NP@CuO-rGO/GCE sensor showed good stability, reproducibility, andrepeatability, and no interference in the electrochemical determination of AA in the presence of other compounds. The proposedmethod was successfully applied using synthetic blood serum samples, with recoveries close to 99.34%.

Keywords:

Electrochemical sensor , ascorbic acid , titania nanoparticles , copper oxide , reduced graphene oxide , TiO2NP@CuO-rGO Nano-composite