Highly Sensitive Electrochemical Sensor for Anticancer Drug by a Zirconia Nanoparticle-Decorated Reduced Graphene Oxide Nanocomposite

Because of their large surface area and conductivity, some inorganic materials have emerged as good candidates for the trace-level detection of pharmaceutical drugs. In the present work, we demonstrate the detection of an anticancer drug (regorafenib, REG) by using an electrochemical sensor based on a nanocomposite material. We synthesized a zirconia-nanoparticle-decorated reduced graphene oxide composite (ZrO₂/rGO) using a one-pot hydrothermal method. Reduction of the graphene oxide supports of the Zr²⁺ ions with hydrazine hydrate helped in preventing the agglomeration of the zirconia nanoparticles and in obtaining an excellent electrocatalytic response of the nanostructure ZrO₂/rGO-based electrochemical sensor. Structural and morphological characterization of the nanostructure ZrO₂/rGO was performed using various analytical methods. A novel regorafenib (REG) electrochemical sensor was fabricated by immobilizing the as-prepared nanostructure ZrO₂/rGO on to a glassy carbon electrode (GCE). The resulting ZrO₂/rGO/GCE could be used for the rapid and selective determination of REG in the presence of ascorbic acid and uric acid. The ZrO₂/rGO/GCE showed a linear response for the REG analysis in the dynamic range 11-343 nM, with a remarkable lower detection limit and limit of quantifications of 17 and 59 nM, respectively. The newly developed sensor was used for the accurate determination of REG in both serum samples and pharmaceutical formulations, with satisfactory results.