Computational study on favipiravir adsorption onto undoped- and silicon-decorated C60 fullerenes

Adsorption and interaction mechanisms of fullerene-based complex systems for possible drug delivery vehicles have been at the center of increasing attention. In the scope of this work, the interaction mechanism between an important antiviral drug favipiravir and silicon-doped/undoped C60 fullerenes have been investigated using density functional theory (DFT). Calculations were carried out in both gas phase and water media to see the possible solvent effects. The effect of adsorption of the favipiravir on the SiC59 fullerene system and the nature of interaction were examined by analyzing the band shifts in the carbonyl stretching vibrations and natural bond orbital (NBO) properties of the examined complexes. Some important structural and electronic properties were reported and discussed as well. It was observed that doping the C60 fullerene nanocages with silicon atom enhanced the adsorption mechanism and calculations performed in water media gave rise to more stable complexes for silicon-doped systems compared to the results obtained for the gas phase. Results and parameters found in the present search reveal further insights into the drug delivery systems.

A DFT study on the geometry, tautomerism and noncovalent interactions of the Mepivacaine drug with the pristine SWCNT and –COOH functionalized SWCNT

The Mepivacaine drug is used as a local anesthetic in dentistry, which could exist as three different tautomers. Herein, geometry, energy behavior as well as tautomerization of these tautomers have been investigated by employing density functional theory (DFT) and considering the solvent effects with the polarizable continuum model (PCM) model. The most stable tautomer of the Mepivacaine has a carbonyl and an –NH amine groups in its structure. The frontier orbitals and the energy gap of the molecule have been computed using the natural bond orbital analysis (NBO). Also, the armchair (5,5) single wall carbon nanotube (SWCNT) was used for investigation of the noncovalent interactions of the Mepivacaine molecule with the pristine SWCNT and the –COOH functionalized SWCNT in several forms. Geometries of the possible forms have been optimized. The most stable form for noncovalent interactions of the drug with each of the pristine and functionalized SWCNTs have been determined. The intermolecular H-bonds have essential role in energy behavior of the noncovalent interactions between the Mepivacaine drug and the investigated SWCNTs.