title: DFT modeling of 45S5 and 77S soda-lime phospho-silicate glass surfaces: clues on different bioactivity mechanism.
abstract: The reactivity of bioglasses, which is related to the dissolution of cations and orthosilicate groups in the physiological fluid, strongly depends on the key structural features present at the glass surfaces. On the basis of the composition and the synthetic routes employed to make the glass, surfaces with very different characteristics and thus presenting different mechanisms of dissolution can be observed. In this paper, the surface structures of two very different bioglass compositions, namely 45S5 (46.1 SiO2, 24.4 Na2O, 26.9 CaO, and 2.6 P2O5 mol %) and 77S (80.0 SiO2, 16.0 CaO, and 4.0 P2O5 mol %), have been investigated by means of periodic DFT calculations based on a PBE functional and localized Gaussian basis set as encoded in the CRYSTAL code. Our calculations show that the two glass surfaces differ by the relative amount of key structural sites such as NBOs, exposed ions, orthosilicate units, and small rings. We have demonstrated how the number of these sites affects the surface stability and reactivity (bioactivity).
authors.affiliation: Dipartimento di Chimica and NIS-Nanostructured Interfaces and Surfaces-Centre of Excellence, Università degli Studi di Torino, Torino, Italy.
authors.forename: Enrico
authors.initials: E
authors.lastname: Berardo
authors.forename: Alfonso
authors.initials: A
authors.lastname: Pedone
authors.forename: Piero
authors.initials: P
authors.lastname: Ugliengo
authors.forename: Marta
authors.initials: M
authors.lastname: Corno
mesh_terms: D017610:Calcium Compounds / Q000737:chemistry*; D005898:Glass / Q000737:chemistry*; D008958:Models, Molecular; D010087:Oxides / Q000737:chemistry*; D017553:Phosphorus Compounds / Q000737:chemistry*; D011789:Quantum Theory; D017640:Silicates / Q000737:chemistry*; D017670:Sodium Compounds / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D017610:Calcium Compounds; D010087:Oxides; D017553:Phosphorus Compounds; D017640:Silicates; D017670:Sodium Compounds; C096707:sodium oxide; C012500:phosphorus pentoxide; C016538:lime