A rational explanation of the vancomycin release from SBA-15 and its derivative by molecular modelling

SBA-15 was investigated for the controlled release of vancomycin. The kinetic of release drastically changed after functionalizing the mesoporous material with octyltrimethoxysilane (C8) chains. That way, the kinetic constant of release decreased from 0.890 min−1/2, for pure SBA-15, to 0.068 min−1/2, for C8-SBA-15. This variation was explained by using, for the first time, molecular modelling and docking. The studies showed the low compatibility between the electrostatic potentials of a pure silica mesoporous model and the vancomycin molecule, because both are essentially negative. However, a model including C8 alkyl chains exhibited a stronger interaction with the drug by weakening the negative surface charge of SBA-15. Furthermore, docking showed that the drug molecules were not able to penetrate into the channels, except the small positive head of vancomycin that interacts with the matrix partially blocking the pores. A strong correlation between the theoretical calculations and the experimental data was established; showing the potentiality of molecular modelling in the design of controlled release devices based in SBA-15 and analogous systems.