Colorimetric insights: Harnessing silver-doped graphitic carbon nitride for uric acid detection

Abstract

Uric acid serves as a vital diagnostic marker for various diseases like arthritis, gout, leukemia, etc. Accurate quantification is critical for effective diagnosis, monitoring, and management of various pathological conditions. Herein, we report the synthesis and characterization of two-dimensional silver-doped graphitic carbon nitride (Ag@g-C₃N₄) as a non-enzymatic colorimetric sensing platform for uric acid. The synthesis was confirmed through various spectroscopic techniques. Fourier-transform infrared spectroscopy (FTIR) showed the characteristic peaks for graphitic carbon nitride (g-C₃N₄) and Ag@g-C₃N₄ nanocomposite, whereas scanning electron microscopy (SEM) displayed the nanoporous morphology of the material. Energy-dispersive X-ray (EDX) and elemental mapping confirmed the presence of various constituent elements and their homogenous distribution respectively. The as-synthesized nanocomposite was used as a new colorimetric sensing platform for uric acid sensing employing 3,3′,5,5′-tetramethylbenzidine (TMB) as an indicating material. This fabricated sensing platform detected uric acid with excellent sensitivity (LOD, 0.12 µM), a wide linear range (1–81 µM) with R² = 0.998, and good selectivity. The proposed sensor worked best at 4 mg of the nanocomposite, pH 6, TMB 15 mM, and 20 mM of H₂O₂, with a response time of 150 seconds. Furthermore, the proposed sensor successfully detected uric acid in real urine sample solutions with good sensitivity and selectivity.