Simultaneous Determination of Ascorbic Acid, Dopamine, Uric Acid, and Acetaminophen on N, P-Doped Hollow Mesoporous Carbon Nanospheres

Dual heteroatom-doped carbon hollow spheres have attracted attention for their intriguing properties, including high surface areas, mesoporosity, sphere wall thicknesses, edge plane defect sites, catalytic active sites, and fast heterogeneous electron-transfer rates. Understandably, the material finds widespread attention in the field of electrochemical sensors. In this work, we have successfully synthesized nitrogen (N) and phosphorus (P) dual doped hollow mesoporous carbon spheres (NPHMCS) by a simple self-polymerization process. The effect of loading a P precursor, namely, phytic acid (PA), on the electrochemical sensing of bioanalytes is investigated in detail. The investigation revealed that 0.6 g loading of PA (NPHMCS-0.6) resulted in an enhanced surface area of 940 m2 g–1, a higher pore volume of 0.40 cm3 g–1, enriched defect sites of 0.99, pyridinic sites of 24.90%, and moderate P–C + P–N sites of 74.65%. The synergistic effect of nitrogen and phosphorous doping along with the abovementioned properties is taken advantage in the fabrication of electrochemical sensors for the simultaneous determination of ascorbic acid (AA), dopamine (DA), uric acid (UA), and acetaminophen (AC). The fabricated sensors displayed a wide linear range of sensing over a concentration from 5 to 6000 μM for AA, 0.5 to 2000 μM for DA, 0.5 to 5000 μM for UA, and 5 to 1200 μM for AC. Based on the calibration plot, the limits of detection (LOD) were calculated to be 0.032, 0.002, 0.005, and 0.020 μM for AA, DA, UA, and AC, respectively. The electroanalytical performance of the fabricated sensor was successfully validated for the analysis of target species in real samples. The developed methodology offers prospective advantages in clinical diagnostics for the simultaneous analysis of small biomolecules and drugs.