Sensing behavior of pristine and doped C70 fullerenes to mercaptopurine drug: a DFT/TDDFT investigation

Abstract

The electronic sensitivity and reactivity of a pristine, Al, and Si-doped C70 fullerene with MP drug were investigated using density functional theory. With adsorption energy of approximately − 6.06 kcal/mol, MP drug was found to be adsorbed physically on pristine C70 through its N-head and to exert no effects on the electrical conductivity of this fullerene. Substituting Al and Si atoms for C atoms in C70 significantly elevates the reactivity of C70 fullerene, respectively at predicted adsorption energies of approximately − 43.06 and − 35.01 kcal/mol. MP drug does significantly affect the energy difference between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), i.e., Eg, and work function of Si and Al-doped C70 fullerene. Significant HOMO destabilization in Si–C70 through MP drug adsorption increases the electrical conductivity of Si–C70 while generating electrical signals and reduces its Eg from 2.13 to 0.79 eV. These signals are associated with the presence of MP drug in the environment. Therefore, Si-doped C70 is found to constitute a promising electronic MP drug sensor. MP drug adsorption increases electron emission from the surface of this sensor and significantly reduces its work function. In contrast to the cases of pristine fullerene, Al, and Si–C70 fullerene doped forms, significant effects of MP drug adsorption on the Fermi levels and work function of Si–C70 make it an Φ-type candidate for MP drug sensors. According to the time-dependent density functional theory, there is a large peak at 1029.65 nm in the steadiest MP/Si–C70 complex.