Assay for uric acid level in rat striatum by a reagentless biosensor based on functionalized multi-wall carbon nanotubes with tin oxide

A novel reagentless amperometric uric acid biosensor based on functionalized multi-wall carbon nanotubes (MWCNTs) with tin oxide (SnO ₂) nanoparticles has been developed. This was successfully applied to assay uric acid levels from an in vivo microdialysis sampling. Compared with unfunctionalized or traditional carboxylic acid (-COOH)-functionalized MWCNTs, the MWCNTs-SnO₂ electrode exhibited higher electrocatalytic oxidation to uric acid. Here, MWCNTs-SnO₂ may act as an efficient promoter, and the system exhibited a linear dependence on the uric acid concentration over the range from 1.0 × 10^-7 to 5.0 × 10^-4 mol L^-1. In addition, there was little ascorbic acid interference. The high sensitivity of the MWCNTs-SnO₂ modified enzyme electrode enabled the monitoring of trace levels of uric acid in dialysate samples in rat striatum.