Fabrication of an efficient and sensitive colorimetric biosensor based on Uricase/ Th-MOF for uric acid sensing in biological samples.

Recently, nanomaterial-based artificial enzymes have expected abundant consideration because of cheap, accessibility, and respectable stability. In this study, we report a Th-MOF artificial peroxidase, which can oxidize 3,3,5,5-tetramethylbenzidine by hydrogen peroxide to yield a blue product. The catalytic behavior of Th-MOF tracked Michaelis-Menten equation and the affinity of this nanozyme to the substrate was higher than horseradish peroxidase as a natural enzyme. The absorbance value of oxidized TMB is linearly associated with the hydrogen peroxide concentration. Since, hydrogen peroxide is the oxidative end product of uric acid (UA) by uricase, an efficient and sensitive approach for uric acid determination was also established. Results showed that Km value of Th-MOF with TMB as a substrate is much lower than that of other mentioned catalysts. The linear regression equations for uric acid substrate was stated as A = 0.0039C + 0.0519 with a correlation coefficient of 0.9955. The linear range for uric acid was from 4.0 to 70 μM, and the LOD was measured as 1.15 μM. Furthermore the absorbance of assay reaction was approximately constant in the following four cycles, demonstrating that Th-MOF catalyst has outstanding stability. Results showed that the public interfering substances had no obvious absorbance values and it was less than 0.1. Results indicated that the recoveries for UA in serum fluids were between 93.10% and 99.04%. The relative standard deviation (RSD, n = 3) at each concentration value was less than 4.3%. UA determination in serum fluids has been confirmed through a comparison between the recommended technique and tedious clinical approaches. Good recovery and accuracy of UA measurement indicated that this established colorimetric sensing system is appropriate for UA revealing in actual experimental samples.