Density functional theory based-study of 5-fluorouracil adsorption on beta-cristobalite (1 1 1) hydroxylated surface: The importance of H-bonding interactions

S. SIMONETTI; A. DÍAZ COMPAÑY; M. E. PRONSATO; A. JUAN; G. BRIZUELA; A. LAM

APPLIED SURFACE SCIENCE

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2015 vol. 359 p. 474 - 479

0169-4332

Silica-based mesoporous materials have been recently proposed as an efficient support for the controlledrelease of a popular anticancer drug, 5-fluorouracil (5-FU). Although the relevance of this topic, theatomistic details about the specific surface-drug interactions and the energy of adsorption are almostunknown. In this work, theoretical calculations using the Vienna Ab-initio Simulation Package (VASP)applying Grimme's-D2 correction were performed to elucidate the drug silica interactions and the hostproperties that control 5-FU drug adsorption on beta-cristobalite (111) hydroxylated surface. This studyshows that hydrogen bonding, electron exchange, and dispersion forces are mainly involved to performthe 5-FU adsorption onto silica. This phenomenon, revealed by favorable energies, results in optimumfour adsorption geometries that can be adopted for 5-FU on the hydroxylated silica surface. Silanols areweakening in response to the molecule approach and establish H-bonds with polar groups of 5-FU drug. The final geometry of 5-FU adopted on hydroxylated silica surface is the results of H-bonding interactionswhich stabilize and fix the molecule to the surface and dispersion forces which approach it toward silica (111) plane. The level of hydroxylation of the SiO2(111) surface is reflected by the elevated number ofhydrogen bonds that play a significant role in the adsorption mechanisms.