A novel electrocatalytic nanocomposite of reduced graphene oxide/silver nanocube hybrid decorated imprinted polymer for ultra-trace sensing of temozolomide

Abstract

A new nanocomposite of reduced graphene oxide/silver nanocube hybrid decorated molecularly imprinted polymer at the surface of a screen-printed carbon electrode was developed for the electroanalysis of an anticancerous drug, temozolomide, at the ultra-trace level. For this, a hybrid of reduced graphene oxide/silver nanocubes was successfully obtained through the simultaneous reduction of Ag⁺ and graphene oxide via simple one-pot green synthesis. Among the various shapes of nanomaterials used in imprinted polymer synthesis, silver nanocubes, as evident from SEM, TEM and, X-ray diffraction methods, have been found to render high surface to volume ratios and a higher electrocatalytic activity. Herein, the synergistic electrocatalytic effect of reduced graphene oxide and silver nanocubes was utilized for decreasing the analyte oxidation overpotential, without any interfacial barrier in between the imprinted film and the electrode surface, owing to the porous texture of the coating. Consequently, approximately 3-fold differential pulse anodic stripping current and ∼5-fold electron transfer rate kinetics were obtained on the reduced graphene oxide/silver nanocube hybrid compared with the simple graphene oxide decorated sensor. The covalent Ag–S links, in between the imprinted film and the silver nanocube decorated screen-printed carbon electrode, were crucial for imparting higher stability to the coating of the film. A perfect linearity in the current–concentration profile was observed, in the range 1.09–144.21 ng mL⁻¹, with the detection limits of 0.16 (aqueous), 0.24 (blood plasma), 0.31 (pharmaceutics), and 0.42 (urine) ng mL⁻¹ (S/N = 3). The proposed sensor was found to be useful in aqueous and real samples (human blood plasma, human urine, and pharmaceutics), without any matrix effect, cross-reactivity, or false-positives.