Uricase Modified Au/Ni/PANI Microrockets to Reduce Uric Acid Level

Herein, we describe a uricase immobilized Au/Ni/PANI microrocket for the motion-based potential hyperuricemia therapy platform. This study has aimed to investigate the use of uricase immobilized magnetically guided microrockets to lower the uric acid level. The outermost Au layer of the microrocket facilitates the immobilization of the uricase enzyme, while the Ni layer allows controlling the motion of the microrocket via an external magnetic field. The innermost layer of PANI was integrated to prevent Ni from leaking. Optimum parameters for enzymatic reactions were determined, and optimum pH for free and immobilized uricase was found to be as 8.5, while optimum temperature was 35 °C for both uricase preparations. Also, the kinetic parameters of both free and immobilized uricase were evaluated. Km value for free uricase was found to be as 0.1212 mM, while immobilized uricase demonstrated lower Km value of 0.017 mM. Vmax of free and immobilized uricase was found to be as 0.8613 µmol/min and 0.02685 µmol/min, respectively. The immobilization process caused uricase to exhibit advanced stability for medium pH, resistance against protease enzymes, improved storage stability, and reusability. It was also observed that the substrate affinity for uric acid increased significantly after immobilization. As a model experiment, activity experiments were performed in an artificial serum medium to demonstrate the potential of the proposed system for future in vivo use. Artificial tests indicated that uricase-modified microrockets showed higher enzymatic activity than that of free counterpart and enzyme-free control studies.Graphical Abstract