Quantitative assessment of uric acid in different biofluids is important as this biomolecule is utilized to diagnose most of purine metabolic disorders. Abnormal level of uric acid, known as hyperuricemia, is the primary cause of gout. Moreover, a number of other diseases, like cardiovascular, neurological, kidney stones, etc., can be linked to hyperuricemia. Selective estimation of uric acid in different biofluids is an open research problem as it has a similar oxidation potential compared to ascorbic acid. The present study involves MoS₂-modified paper substrate as a sensing platform to detect uric acid distinctively. A single-step hydrothermal method was employed to grow MoS₂ micro flower over the paper substrate. The modified paper substrate was characterized with FESEM, XRD and Raman Spectroscopy to validate the proper formation of MoS₂ microflowers. These MoS₂-modified paper sensors were further used to determine different uric acid concentrations through a non-enzymatic approach where oxidation of uric acid occurs at the surface of the sensing region. To promote the suitability of MoS₂ towards selective detection of uric acid, an extensive first principle calculation has been carried out by inserting different biomolecules i.e. uric acid, ascorbic acid, and dopamine inside the unit cell of 2H-MoS₂. The obtained electronic band gap and projected density of states analysis confirm the selectivity of the MoS₂ towards uric acid detection. The theoretical calculations were further correlated with the experimentally obtained conductivity by Van der pauw method. Different electrochemical measurements like cyclic voltammetry and differential pulse voltammetry were employed to verify the change in oxidation potential of uric acid in presence of MoS₂-modified paper substrate. These experimental findings can also be corroborated by the charge redistribution of uric aid adsorbed MoS₂ structure obtained through Löwdin population analysis. Thus, incorporating MoS₂ as sensing material helps in producing distinguishable outputs in differential pulse voltammetry experiments which can also be correlated with the ab-initio calculations.

Souvik Biswas

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