Theoretical Investigation of Single-Atoms Encapsulated by Fullerenes (C59X: X=As, Ga, Ge) as Biosensors For Uric Acid (UA)

This work focuses on comparative investigation of three different doped surfaces on a nano-cage C₅₉As, C₅₉Ga and C₅₉Ge to understand their sensitivity and ability to adsorbed uric acid (UA). This is done using the density functional theory (DFT) computation, employing ωB97XD/def2SVP level of theory. After interaction of the surfaces with UA, FMO results reveal that UA@C₅₉As is more reactive with Eg=5.1911 eV and UA@C₅₉Ga is more stable with Eg=5.3304 eV, while UA@C₅₉Ge is relatively reactive and relatively stable with Eg=5.2145 eV. Geometric optimization analysis reveals that UA@C₅₉Ge shows the best interaction with the least adsorption distance (1.9437 Å) and UA@C₅₉Ga shows a relatively good interaction with adsorption distance (1.9674 Å) while UA@C₅₉As reveal the poorest interaction with adsorption distance of (3.6370 Å). The calculated thermodynamic parameters deduced that UA@C₅₉Ga is more stable compared to UA@C₅₉As and UA@C₅₉Ge complexes, due to the fact that the calculated values of ℇ_°+ℇ_ZPE, ℇ_°+G_corr, ℇ_°+H_corr and ℇ_°+E_tot are less negative in compound UA@C₅₉Ga. Negative E_ads values of UA@C₅₉As (−0.5968 eV), UA@C₅₉Ga (−1.8798 eV) and UA@C₅₉Ge (−1.1656 eV) were observed from adsorption studies and its sensor mechanism implying an enhanced chemical adsorption was manifested and this indicates the presence of a covalent interaction. Similarly, the result of interaction energy (E_int) reveal UA@C₅₉Ge to have an E_int of 22.3978 eV greater than UA@C₅₉Ga (21.5832 eV) and far greater than UA@C₅₉As (2.4593 eV) there by confirming UA@C₅₉Ga and UA@C₅₉Ge to be strongly interacted. However, all analysis in this work has shown that C₅₉Ge is the best promising biomarker candidate for adsorbing UA, although C₅₉Ga has also demonstrated a good UA adsorption candidate.