Atomic scale modelling of the adhesion of hydroxy-apatite to bio-active glasses
Lead Research Organisation:
University College London
Department Name: Chemistry
Abstract
The bioactivity of materials used as bone replacements, or for bone repair, stems from the formation of a hydroxy-apatite layer on the surface of the biomaterial Bioglass is one of a number of bioactive glasses that have been found readily to bond to bone and soft tissue, and is used by doctors and dentists to repair bones, joints and teeth. The aim of the research is to employ state-of-the-art computer simulation techniques to investigate key aspects of the structure/chemistry relationships of the interactions between bio-active glasses and the major natural rnammalian bone and teeth enamel constituent, hydroxyapatte, with a strong emphasis on the investigation df the major factors determining the nature of the interface: firstly the epiitaxial relationship between the bio. active glass surface and the apatite material, i.e. () structure of the interface, (in) strength of bonding, (ii) composition of the bio-active glass, and (iv) orientation of the apatite crystal. Secondly, we will investigate the nucleation of apatite at the bio-active glass surface, i.e. () nucleation sites, (i) the dynamics of the glass surface, and (o) the intergrowth of the apatite with the partially dissolving glass.Hence, we intend to concentrate on the following issues:Development of models for the interactions between bio-active glasses and hy droxy-apatite; Investigation of glass surface modifications, e.g. cation composition, surface hydration; Modelling the effect of orientation of the apatite crystallite to the glass surface on the strength of adhesion; Nucleation of the apatite at the bio-active glass surface in simulated body fluid.The outcome of the project will be an improved and detailed understanding of the interaction of hydroxy-apattifte with realistic bio-active glasses, which is highly(1) Development of models for the interactions between bio-active glasses and hydroxy-apatite;(2) Investigation of glass surface modifications, e.g. cation composition, surface hydration;(3) Modelling the effect of orientation of the apatite crystallite to the glass surface on the strength of adhesion;(4) Nucleation of the apatite at the bio-active glass surface in simulated body fluid.The outcome of the project will be an improved and detailed understanding of the interaction of hydroxy-apatite with realistic bio-active glasses, which is highly relevant to bio-medical applications of bio-active glasses as surgical implant materials.
Organisations
Publications
Almora-Barrios N
(2011)
Density Functional Theory Calculations and Molecular Dynamics Simulations of the Interaction of Bio-molecules with Hydroxyapatite Surfaces in an Aqueous Environment
in MRS Proceedings
Almora-Barrios N
(2010)
A density functional theory study of the interaction of collagen peptides with hydroxyapatite surfaces.
in Langmuir : the ACS journal of surfaces and colloids
Almora-Barrios N
(2010)
Modelling the interaction of a Hyp-Pro-Gly peptide with hydroxyapatite surfaces in aqueous environment
in CrystEngComm
Collier TA
(2015)
Preferential sites for intramolecular glucosepane cross-link formation in type I collagen: A thermodynamic study.
in Matrix biology : journal of the International Society for Matrix Biology
De Leeuw N
(2010)
Computer simulations of structures and properties of the biomaterial hydroxyapatite
in Journal of Materials Chemistry
Hernandez S
(2015)
Effect of Chondroitin 4-Sulfate on the Growth and Morphology of Calcium Oxalate Monohydrate: A Molecular Dynamics Study
in Crystal Growth & Design
Lemaire T
(2015)
Bone water at the nanoscale: a molecular dynamics study.
in Computer methods in biomechanics and biomedical engineering
Mkhonto D
(2008)
The effect of surface silanol groups on the deposition of apatite onto silica surfaces: a computer simulation study.
in Journal of materials science. Materials in medicine
Pham T
(2015)
Properties of water confined in hydroxyapatite nanopores as derived from molecular dynamics simulations
in Theoretical Chemistry Accounts
Rabone JA
(2006)
Interatomic potential models for natural apatite crystals: incorporating strontium and the lanthanides.
in Journal of computational chemistry
| Description | The bioactivity of materials used as bone replacements, or for bone repair, stems from the formation of a hydroxy-apatite layer on the surface of the biomaterial. Bioglass is one of a number of bioactive glasses that have been found readily to bond to bone and soft tissue, and is used by doctors and dentists to repair bones, joints and teeth. The aim of the research was to employ state-of-the-art computer simulation techniques to, first, investigate key aspects of the structure/chemistry relationships of the bio-glasses themselves, which are only bio-active in a very small compositional range. Secondly, we have studied the interaction of the major natural mammalian bone and teeth enamel constituent, hydroxy apatite with the surfaces of a number of silicate structures as model glass surface, with a strong emphasis on the investigation of the major factors determining the nature of the interface: firstly the epitaxial relationship between the silicate surface and the apatite material, i.e. (i) structure of the interface, (in) strength of bonding, (ii) composition of the glass surface (charges versus hydrated), and (iv) orientation of the apatite crystal. Finally, we have investigated the nucleation of apatite at the bio-active glass surface, concentrating on the different nucleation sites at the glass surfaces and the intergrowth of the apatite with the partially dissolving glass. Over the course of this project we have achieved the following: (i) We have developed a new potential model for Molecular Dynamics (MD) simulations of bio-glasses, including silicate and phosphate network-forming groups and Ca and Na cations. We have also derived a new full-charge potential model for the hydroxyapatite material, which is fully compatible with the new glass potential and the combination has been applied to the nucleation of hydroxyapatite at the glass surface; (ii) Using both ab initio and classical MD simulations, we have identified the major ring and chain structures in phosphor-silicate glasses of different compositions and quantitatively linked the molecular structure of the glass to its bio-activity. (iii) Finally, we have carried out detailed atomic-level investigations of the interface between silicate surfaces and the hydroxyapatite mineral, identifying the relative importance of a number of factors to the adhesion of the apatite to the substrate surface: The (de)hydration of the substrate surface primarily affects the strength of interaction (the presence of surface hydroxy groups weakens the interaction), followed by the geometry of the substrate surface and, finally, the epitaxy of the apatite film with respect to the surface. The outcome of the project is, first, an improved understanding of the effect of glass composition on the atomic-level structure of the silicate and phosphor-silicate glasses, which links the structure to the bio-activity of the glasses. Second, the project has led to detailed insight into the major factors affecting the adhesion of the apatite mineral to the substrate surface, which are both highly relevant to bio-medical applications of bio-active glasses as surgical implant materials. A comprehensive final report was submitted to the EPSRC upon completion of the grant. |
| Exploitation Route | Could be used by tissue engineers to improve adhesion of bio-compatible coatings on implant materials |
| Sectors | Healthcare |
| Description | Peer-reviewed publications, presentations at conferences |
| First Year Of Impact | 2008 |
| Sector | Healthcare |
| Impact Types | Societal |
| Description | Royal Society Wolfson Research Merit Award |
| Amount | £87,500 (GBP) |
| Organisation | The Royal Society |
| Sector | Charity/Non Profit |
| Country | United Kingdom |
| Start | 07/2009 |
| End | 07/2014 |