Detection of Histamine and Serotonin as Chronic Stress Biomarkers Using Graphyne-based Sensor: A DFT Study

Abstract

Chronic stress is a leading cause of mental illnesses that is interceded by neuroinflammation and poses one of the most critical public health challenges globally therefore, a theragnostic strategy is needed for effective diagnosis of stress. Neuroinflammation induces an increase in histamine and a decrease in serotonin levels in blood during chronic stress. The sensitivity of pristine and alkali metal (IA = Li, Na, and K) doped C24H12 toward histamine and serotonin are probed herein at DFT/ωB97XD/6- 31+G (d, p) level of theory in the water phase. The -NH2 group of histamine and -OH group of serotonin are coordinated with pristine and metal-doped C24H12 nanosheets. The adsorption of histamine and serotonin is an exothermic process and physi-chemisorbed as their adsorption energies range from -40 to -60 kJ/mole per atom for all complexes except His@C24H12, His@KC24H12, and Ser@C24H12. Considerable, charge transfer from biomarkers to the C24H12 except for Ser@C24H12 is revealed via NBO analysis and confirmed by.MEP, UV-visible, and IR spectroscopic analyses. Upon the adsorption of the biomarkers, the λmax of pristine C24H12 remains unchanged but, in metal-doped C24H12, a bathochromic effect is observed. The significant shift in vibrational frequencies of -NH and -OH stretch occurred due to charge transfer toward C24H12. Furthermore, the band gap of the pristine C24H12 is 6.86 eV which remains constant even after histamine and serotonin adsorption. However, the doping of alkali metals leads toward a significant decrease of the band gap of about 4.60 eV revealing that doping facilitated the charge transfer from biomarkers to graphyne for effective sensing. The QTAIM and IRI studies show the presence of non-covalent interactions among the biomarkers and C24H12. Finally, a shorter recovery time (fast desorption) is found in vacuum ultraviolet light, indicating the pristine and metal-doped C24H12 nanosheets as a reusable or non-disposable sensor. Therefore, it concludes that metal-doped C24H12 nanosheets are more sensitive toward histamine and serotonin adsorption than pristine C24H12.