Modeling of photofunctional transition metals (Mn, Re, Ir) complexes towards the effective detection of uric acid (UA) as biomarker for kidney dysfunction

Abstract

The potential of isatinic quinolyl Schiff bases transition metal complexes as electronic biosensors for detecting kidney dysfunction biomarker (uric acid) denoted as UA was investigated from first principles computations. The adsorption of UA onto the metal centres of Ir, Mn and Re complexes of (Z)-5-bromo-3-(quinolin-8-ylimino)indolin-2-one and (Z)-5-nitro-3-(quinolin-8-ylimino)indolin-2-one, designated as L1 and L2 were studied extensively. Uric acid has been considered an essential biomarker for oxidative stress, human arthritis, cardiomyopathy, and hyperuricemia. Biomarkers perform a pivotal role in the successful diagnosis and treatment of several diseases. Dispersion-corrected DFT calculations were performed, and the results evinced that the modelled transition metal complexes are promising candidates for UA detection. It was found that UA is chemisorbed by coordinating with the metal centers and ligands at a 3.873 Å distance on average with the adsorption enthalpies being −37.11 kcal/mol, –32.95 kcal/mol, and −21.44 for UA@L2Mn, UA@L2Re and UA@L2Ir complexes respectively. While the computed adsorption enthalpies for L1 complexes were found to be −24.47 kcal/mol. –22.11 kcal/mol and –22.19 kcal/mol respectively for UA@L1Ir, UA@L1Mn and UA@L1Re complexes showing that the L2 complexes acted as better sensors for UA. The sensitivity of UA by the metal complexes was influenced by the binding conformation of UA and the adsorption sites of the ligands. Overall, the metal complexes demonstrated high sensitivity with high values of work function up to 7.13 eV being recorded and hence making suitable substrates for work-function based sensors. Good stability and excellent conductivity even with the adsorption of UA was maintained and the desorption test-based on the transition state theory was considered and the complexes showed promising results for practical implementation as UA biosensors.