PtAu/C based bimetallic nanocomposites for non-enzymatic electrochemical glucose detection

Nanocomposites of Pt:Au (ratios 1:1, 1:2, 1:3 and 1:4) on activated carbon were synthesized using a novel synthetic route, leading to materials with surface enrichment of Pt(0) with high catalytic performance for the direct electro-oxidation of glucose. The overall metallic content (Pt + Au) was 20% (w/w) and the bimetallic nanoparticles were found to be uniformly distributed in the activated carbon (80%) matrix. The surface morphology and composition of the synthesized materials were characterised using scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDX), thermogravimetric analysis (TGA), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Cyclic voltammetry was employed in order to confirm the typical metallic electrochemical response of Pt, Au and Pt-Au nanomaterials. The optimum nanocomposite material (Pt₁Au₃/C) for glucose electro-oxidation exhibited a sensitive (4.7 μA mM^-1 cm ^-2, limit of detection = 2.0 μM) response to glucose over the range 0-10 mM (r² = 0.99) at E_app = 0.35 V vs Ag/AgCl under neutral conditions (phosphate buffer solution, pH 7.4). The electrocatalysts showed an excellent response to glucose in comparison to other structurally related sugars (no/negligible response by xylose, maltose, galactose and fructose) and normally co-existing electroactive species (minimal response for ascorbic acid, acetaminophen, uric acid and dopamine). Overall, the materials examined demonstrated excellent glucose sensing capability, while eliminating the pH, temperature sensitivity and lifetime issues associated with enzyme based glucose systems and demonstrate great promise in the quantification of glucose in real clinical samples.