Uric Acid Colorimetric Detection Involving Mno2 Nanosheets and O-Phenylenediamine

Abstract

Serum uric acid (UA) content is an important reference indicator for diagnosing diseases. In the present work, MnO2 nanosheets (MnO2 NSs) were synthesized, as well as an enzyme-free colorimetric method for sensitive determination of UA was developed. It was based on the strong oxidation capacity of MnO2 NSs, which could oxidize colorless o-phenylenediamine (OPD) to generate yellow product diaminophenazine (oxOPD) with an absorption peak at 420 nm. However, the addition of UA caused the structure of MnO2 NSs to be destroyed and reduced to Mn2+, in turn causing a decrease in the efficiency of oxidation and absorbance intensity. Further investigation indicated that the decrease in absorbance increased with the increase of UA concentration. Under the optimized conditions of pH 7.4, temperature 60°C, incubation time 50 min, and MnO2 NSs 20 μM, the proposed method displayed a detection limit of 0.87 μM and a linear response range of 1.0 to 90 μM, making its detection of UA simple, fast, and sensitive. Furthermore, the achieved good recovery (95.3% ~ 102.8%) in serum samples confirmed the potential of the developed method for practical applications.

Keywords: Colorimetry, Determination, uric acid, MnO2 nanosheets