Molecular dynamics simulations study of the structure and dynamics of nimodipine confined in an ordered mesoporous silica matrix

Abstract

The structural and dynamical properties of nimodipine (a drug from the family of derivatives of 1,4-dihydropyridine) confined in silica matrix were studied by means of molecular dynamics simulations as a function of pore filling. Nimodipine molecules are connected with the silica surface via different types of hydrogen bonds, which have different average lifetimes (from 20 to 80 ps). The interaction with the silica surface inhibits the translational diffusion, while for molecules situated in the center of the channel translational diffusion is clearly observed, even if slow. The silica surface and the presence of additional layers of molecules in the pore also influence significantly the internal mobility, as determined by the reorientation of the methyl groups and the molecular chains. As the different degree of pore filling cannot be easily explored experimentally, molecular dynamics simulations gave unique access to the analysis of how the structure and dynamics of confined nimodipine depend on this parameter.