Undiluted human whole blood uric acid detection using a graphitized mesoporous carbon modified electrode: a potential tool for clinical point-of-care uric acid diagnosis

Abstract

Direct sensing of uric acid (UA) in an undiluted whole blood sample is reported here taking human whole blood as an analyte and a self-supporting electrolyte. Among various solid electrodes (Pt, Au, GCE, and GCE/Nafion) and carbon nanomaterials (carbon nanofibers, graphene oxide, graphite nanopowder, graphitized mesoporous carbon (GMC), single-walled carbon nanotubes, and multiwalled carbon nanotubes) tested, a GMC-modified glassy carbon electrode, designated as GCE/GMC, showed a remarkable response towards direct electrochemical oxidation of blood uric acid at ∼0.25 V vs. Ag/AgCl, unlike the poor and/or feeble current signals with the other unmodified and modified electrodes. It is plausible that the mesoporous nature of the GMC favours the formation of a blood–GMC bio-corona through internalization and provides straight access to blood-matrixed uric acid. Furthermore, the effects of the scan rate and interference with various biochemicals on the GCE/GMC were analysed. The electrochemical oxidation reaction is found to be diffusion controlled in nature and there is no interference from common biochemicals like ascorbic acid, glucose, tryptophan, H₂O₂, xanthine, hypoxanthine, cysteine, nitrate, nitrite, and sulfide in blood. Real blood UA sample analysis was demonstrated with comparable UA analysis results from the clinical measurement.