Biosensor for Monitoring Uric Acid in Wound and Its Proximity: A Potential Wound Diagnostic Tool

This work reports a bi-enzymatic biosensor for monitoring uric acid (UA) in biofluids extracted from wound, perilesional skin and healthy skin. The biosensor is composed of uricase (UOx) as a biocatalyst for UA oxidation, horseradish peroxidase (HRP) for electron transfer and a nanocomposite of multi-walled carbon nanotubes (MWCNTs) and Au nanoparticles (AuNPs) as the substrate. The bi-enzymatic approach provided a two-fold enhancement in current response, while the nanocomposite facilitated higher enzyme loading and fast electron transfer enabling a 2-fold increase in current response. The biosensor was able to measure UA levels in human wound exudate and in biofluids extracted from perilesional and healthy skin. The biosensor exhibited a lowest detectable concentration of 9.91 μM with a sensitivity of 2.5 nA μM−1. The UA levels in wound exudate and biofluid extract from perilesional skin were 3.7 and 1.2 times higher than in healthy skin. This result opened a potential way to use the biofluid in wound proximity as a biomarker for prolonged measurements, preventing electrode occlusion and sensor fouling by the wound debris. The electrode fouling studies demonstrated that the electrode with adsorbed wound exudate had 1.5 times reduction in current compared to electrode adsorbed with biofluid extract from perilesional skin.