title: Biomimetic coating of organic polymers with a protein-functionalized layer of calcium phosphate: the surface properties of the carrier influence neither the coating characteristics nor the incorporation mechanism or release kinetics of the protein.
abstract: Polymers that are used in clinical practice as bone-defect-filling materials possess many essential qualities, such as moldability, mechanical strength and biodegradability, but they are neither osteoconductive nor osteoinductive. Osteoconductivity can be conferred by coating the material with a layer of calcium phosphate, which can be rendered osteoinductive by functionalizing it with an osteogenic agent. We wished to ascertain whether the morphological and physicochemical characteristics of unfunctionalized and bovine-serum-albumin (BSA)-functionalized calcium-phosphate coatings were influenced by the surface properties of polymeric carriers. The release kinetics of the protein were also investigated. Two sponge-like materials (Helistat® and Polyactive®) and two fibrous ones (Ethisorb™ and poly[lactic-co-glycolic acid]) were tested. The coating characteristics were evaluated using state-of-the-art methodologies. The release kinetics of BSA were monitored spectrophotometrically. The characteristics of the amorphous and the crystalline phases of the coatings were not influenced by either the surface chemistry or the surface geometry of the underlying polymer. The mechanism whereby BSA was incorporated into the crystalline layer and the rate of release of the truly incorporated depot were likewise unaffected by the nature of the polymeric carrier. Our biomimetic coating technique could be applied to either spongy or fibrous bone-defect-filling organic polymers, with a view to rendering them osteoconductive and osteoinductive.
authors.affiliation: Centre of Regenerative Medicine for Skeletal Tissues, Department of Clinical Research, University of Bern, Bern, Switzerland.
authors.forename: Gang
authors.initials: G
authors.lastname: Wu
authors.forename: Yuelian
authors.initials: Y
authors.lastname: Liu
authors.forename: Tateyuki
authors.initials: T
authors.lastname: Iizuka
authors.forename: Ernst B
authors.initials: EB
authors.lastname: Hunziker
mesh_terms: D000818:Animals; D040761:Biomimetic Materials / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism; D002130:Calcium Phosphates / Q000737:chemistry*; D002417:Cattle; D020099:Coated Materials, Biocompatible / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism; D004337:Drug Carriers / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism*; D016650:Fluorescein-5-isothiocyanate / Q000032:analysis / Q000378:metabolism; D019344:Lactic Acid / Q000737:chemistry; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D011091:Polyesters / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry; D011100:Polyglycolic Acid / Q000737:chemistry; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry; D011506:Proteins / Q000008:administration & dosage* / Q000493:pharmacokinetics* / Q000502:physiology; D012710:Serum Albumin, Bovine / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000502:physiology; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties
chemical_list: D002130:Calcium Phosphates; D020099:Coated Materials, Biocompatible; D004337:Drug Carriers; D011091:Polyesters; D011108:Polymers; D011506:Proteins; C072932:polyethylene oxide-polybutylene terephthalate copolymer; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D012710:Serum Albumin, Bovine; D019344:Lactic Acid; D011092:Polyethylene Glycols; C020243:calcium phosphate; D016650:Fluorescein-5-isothiocyanate