Theoretical study of cephalexin drug supported onto silica nanocarrier

A. DIAZ COMPAÑY; S. SIMONETTI

Canberra

Conferencia; International Conference on Nanoscience and Nanotechnology; 2016

Cephalexin adsorption from aqueous solutions using SBA-15 silica as adsorbent and the influence of pH solution on drug adsorption were previously experimental studied. In this paper, in order to have a better knowledge about the way the drug molecules interact with the inorganic matrix, the adsorption process was estimated by applying the computational chemistry software VASP (Vienna Ab initio simulation package). A strong correlation between the theoretical calculations and the experimental results was established, showing that the adsorbate?adsorbent interaction is pH dependent. Calculated cephalexin horizontal adsorption energy was almost 7 eV more stable than the one corresponding to vertical adsorption, and also the lowest enthalpy of contact and the maximum adsorption percent were found for the cationic cephalexin?silica system. Cephalexin adsorption through the NH3+ group is 6 eV stronger than the molecule adsorption through the COO− group. In agreement with experimental results, the theoretical predictions indicate that the electrostatic attraction between CPX ions and the surface of silica is favored at pH values between 2 and 2.56, the maximum being for cephalexin adsorption obtained at pH 2.3.