title: Calcium-binding phospholipids as a coating material for implant osteointegration.
abstract: Among the many biomolecules involved in the bone mineralization processes, anionic phospholipids play an important role because of their ability to bind calcium. In particular, phosphatidylserine is a natural component of the plasmalemma and of the matrix vesicles generated from the osteoblast membrane to create nucleation centres for calcium phosphate crystal precipitation. In the present work, we demonstrate that calcium-binding phospholipids can be used as biomimetic coating materials for improving the osteointegration of metal implants. Relatively thick phosphatidylserine-based coatings were deposited on titanium coupons by dip-coating. Upon dehydration in a simulated body fluid phospholipids were quickly crosslinked by calcium and re-arranged into a three-dimensional matrix able to induce rapid formation of a calcium phosphate mineral phase. The rate of mineralization was shown to be dependent on the adopted coating formulation. In the attempt to closely mimic the cell membrane composition, heterogeneous formulations based on the mixing of anionic phospholipids (either phosphatidylserine or phosphatidylinositol) with phosphatidylcholine and cholesterol were synthesized. However, surface plasmon resonance studies as well as scanning electron microscopy and elemental analysis demonstrated that the homogeneous phosphatidylserine coating was a more effective calcification environment than the heterogeneous formulations.
authors.affiliation: School of Pharmacy and Biomolecular Sciences, University of Brighton, Lewes Road, Brighton BN2 4GJ, UK. m.santin@brighton.ac.uk
authors.forename: Matteo
authors.initials: M
authors.lastname: Santin
authors.forename: William
authors.initials: W
authors.lastname: Rhys-Williams
authors.forename: Josephine
authors.initials: J
authors.lastname: O'Reilly
authors.forename: Martyn C
authors.initials: MC
authors.lastname: Davies
authors.forename: Kevin
authors.initials: K
authors.lastname: Shakesheff
authors.forename: William G
authors.initials: WG
authors.lastname: Love
authors.forename: Andrew W
authors.initials: AW
authors.lastname: Lloyd
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Denyer
mesh_terms: D040761:Biomimetic Materials / Q000138:chemical synthesis / Q000737:chemistry*; D001826:Body Fluids / Q000737:chemistry; D002113:Calcification, Physiologic / Q000502:physiology; D002130:Calcium Phosphates / Q000737:chemistry*; D020099:Coated Materials, Biocompatible / Q000138:chemical synthesis / Q000737:chemistry*; D003198:Computer Simulation; D008855:Microscopy, Electron, Scanning; D016348:Osseointegration / Q000502:physiology*; D010743:Phospholipids / Q000737:chemistry*; D019736:Prostheses and Implants; D020349:Surface Plasmon Resonance
chemical_list: D002130:Calcium Phosphates; D020099:Coated Materials, Biocompatible; D010743:Phospholipids