Highly tuned cobalt-doped MnO2 nanozyme as remarkably efficient uricase mimic

• Published in: Applied nanoscience 2020-01, Vol.10 (1), p.317-328
• Main Authors: Parmekar, Mira V., Salker, A. V.
• Format: Article
• Language: English
• Subjects: Arthritis; Chemistry and Materials Science; Degradation; Enzymes; Manganese dioxide; Materials Science; Membrane Biology; Metabolic disorders; Morphology; Nanochemistry; Nanoparticles; Nanotechnology; Nanotechnology and Microengineering; Original Article; Oxidase; Rheumatism; Singlet oxygen; Uric acid
• ISSN: 2190-5509; 2190-5517
• DOI: 10.1007/s13204-019-01118-x

Gouty arthritis is a commonly occurring metabolic disorder in adult humans. It is caused by accumulation of uric acid (UA) in the joints owing to lack of any enzyme like uricase, which can metabolise excess UA in the human body. In this work, we propose a solution for the same. After testing the oxidase-like activity of Co-doped MnO 2 using 3,3′,5,5′-tetramethylbenzidine (TMB), as less as 50 μg mL −1 of this catalyst was found to readily oxidise and completely degrade a 50 μM uric acid solution at 37 °C within 4 h (pH 7.4). The rate of the reaction found to be 1.208 × 10 −4  s −1 at this temperature. The result clearly indicates better activity of these nanoparticles over bacterial uricase enzyme as the activation energy of the reaction decreased from the reported value of 53 to 43 kJ mol −1 in this work. This is by far the lowest reported E act by any enzyme mimic for uricase. Composed of two bio-relevant metals namely Mn and Co, the nanozyme is economical as well as safe to use for treatment of gout. The nanozyme could be successfully recycled four times with no loss in the oxidase-like activity and proved to be quite stable in the employed conditions as the metal content and morphology were retained even after reuse. Generation of in situ singlet oxygen/superperoxide radical-type species was another striking feature of the employed nanozyme. LC–MS data of the degraded products further gave insights on the pathway followed for degradation over the nanozyme. Overall, a bio-relevant as well as cost effective alternate for the treatment of gout envisaged in the current study.