Sensing of uric acid via cascade catalysis of uricase and a biomimetic catalyst

Abstract A uric acid (UA) sensing system that exploits the cascade catalysis of a natural enzyme and a biomimetic catalyst was developed. In the cascade catalysis system, UA was oxidized by uricase (UOx) to release hydrogen peroxide (H2O2), which was further used as a substrate for the oxidation of o-phenylenediamine (OPD) by a biomimetic peroxidase-like catalyst (PMOx). OPD oxidation resulted in a change in color of the UA solution, which enabled quantification of UA through optical spectroscopy. The cascade catalysis system exhibited sensitivity for UA at concentrations greater than 0.01 mM, with linear correlation to the optical intensity. Furthermore, the cascade catalysis system exhibited high selectivity toward UA because of the inherent selectivity of UOx. The cascade catalysis system showed maximum activity at 35 °C because of the deactivation of UOx at higher temperatures, although the PMOx exhibited better catalytic activity with increasing temperature. The sensing of UA in serum samples was examined using the developed system. The sensitivity of this cascade catalysis system was comparable to that of a clinical method, with 5.45% deviation. The combinational use of a natural enzyme and a biomimetic catalyst demonstrated in this study may be further applicable for the development of other biological sensors with advantages in thermal stability and production cost.