Large scale periodic B3LYP modeling of oxides relevant as biomaterials

In this comunication the properties of amorphous silica, hydroxyapatite and the Hench’s bio- glass have been addressed by large scale B3LYP simulation. Amorphous silica is a key in- organic material with applications in many fields, such as chromatography, microelectronics, metal supported catalysis, and in biomaterials science. Moreover, amorphous silica is the ba- sic constituent of mesoporous ordered materials like MCM-41. These materials present high surface areas and high pore volumes, which make them very attractive supports for adsorp- tion or immobilization of biologically relevant molecules in confined spaces. Indeed, due to their regular pore distribution, they are excellent candidates for controlled drug delivery systems, as evidenced for the first time by the confinement of ibuprofen in MCM-41 matri- ces. Realistic models of amorphous silica surfaces with different degree of hydroxylation and MCM-41 mesorporous material will be illustrated as the result of large scale B3LYP simulation. Comparison with structural and vibrational experimental data confirms the validity of these models, which will be very useful for future computational studies involving interaction with biomolecules. Hydroxyapatite (HA, Ca10(PO4)6(OH)2) is the main constituent of the mineral phase in mammalian bones and teeth enamel and it is widely applied as an orthopaedic and dental biomaterial. The Hench Bioglass R° 45S5 (46.1% SiO2 26.9% CaO 24.4% Na2O and 2.6% P2O5 molar composition) is of great interest in medical applications since in the presence of body fluids, and depending upon the rate of ion release and resorption, it creates chemical gradients which promote the formation of a layer of biologically active bone-like hydroxyap- atite at the implantation interface. In this work, B3LYP simulations of the interaction between a miniprotein (13 aminoacids) with the most stable (001) surface of HA will be reported. The same approach was also adopted for simulating the full vibrational spectrum of an amorphous model of the Hench’s glass which allowed, for the first time, the detailed assignments of the IR experimental bands. All calculations have been possible thanks to the generous allowance of computer resources provided by the Barcelona Supercomputing Center (http://www.bsc.es/).