Simultaneous and Ratiometric Electrochemical Determination of Uric Acid and Hypoxanthine Based on In Situ Carbonized Polydopamine Graphene Paper

Highlevels of uric acid (UA) and xanthine (XA) in the human bodycan lead to various illnesses, highlighting the crucial need to detectUA and XA levels in the body. In this work, a ratiometric electrochemicaldetection platform was constructed for the simultaneous determinationof UA and XA. Polydopamine (PDA) was initially modified in situ ongraphene paper (Gp) and carbonized to fabricate the cPDA-Gp electrode.Methylene blue (MB) is coupled to cPDA-Gp as an internal referenceand is designated as MB/cPDA-Gp. The electrochemical behavior of UAand XA on MB/cPDA-Gp was studied by cyclic voltammetry and differentialpulse voltammetry. There were distinct anodic peaks on the electrodethat corresponded to the oxidation of UA and XA in the concentrationranges of 0.6-350 and 2-160 mu M, with detectionlimits of 0.2 and 0.67 mu M, respectively (S/N = 3). For simultaneousdetection of changes in UA and XA concentrations, the response rangewas 1-300 mu M, with detection limits of 0.34 and 0.67 mu M (S/N = 3), respectively. The sensing platform has been successfullyutilized to detect UA and XA in real samples with satisfactory results,indicating that it can be a reliable sensor for detecting these analytes.