title: Effect of Assembly pH on Polyelectrolyte Multilayer Surface Properties and BMP-2 Release.
abstract: The effect of solution pH during layer-by-layer assembly of polyelectrolyte multilayer (PEM) coatings on properties relevant to orthopedic implant success was investigated. Bone morphogenetic protein 2 (BMP-2), a potent osteoconductive growth factor, was adsorbed onto the surface of anodized titanium, and PEM coatings prepared from solutions of poly-l-histidine and poly(methacrylic acid) were built on top of the BMP-2. High levels of BMP-2 released over several months were achieved. Approximately 2 μg/cm(2) of BMP-2 were initially adsorbed on the anodized titanium and a pH-dependent release behavior was observed, with more stable coatings assembled at pH = 6-7. Three different diffusion regimes could be determined from the release profiles: an initial burst release, a sustained release regime, and a depletion regime. BMP-2 was shown to maintain bioactivity after release from a PEM and the presence of a PEM was shown to preserve BMP-2 structure. No visible change was observed in surface roughness as the assembly pH was varied, whereas the surface energy decreased for samples prepared at more basic pH. These results indicate that the initial BMP-2 layer affects PEM surface structure, but not the functional groups exposed on the surface.
authors.affiliation: Departments of †Chemical Engineering, ‡Mechanical Engineering, and §Biomedical Engineering, Worcester Polytechnic Institute , 100 Institute Road, Worcester, Massachusetts 01609, United States.
authors.forename: Claire
authors.initials: C
authors.lastname: Salvi
authors.affiliation: Departments of †Chemical Engineering, ‡Mechanical Engineering, and §Biomedical Engineering, Worcester Polytechnic Institute , 100 Institute Road, Worcester, Massachusetts 01609, United States.
authors.forename: Xuejian
authors.initials: X
authors.lastname: Lyu
authors.affiliation: Departments of †Chemical Engineering, ‡Mechanical Engineering, and §Biomedical Engineering, Worcester Polytechnic Institute , 100 Institute Road, Worcester, Massachusetts 01609, United States.
authors.forename: Amy M
authors.initials: AM
authors.lastname: Peterson
mesh_terms: D000818:Animals; D055396:Bone Morphogenetic Protein 2 / Q000008:administration & dosage / Q000737:chemistry* / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D016503:Drug Delivery Systems; D065546:Drug Liberation; D006639:Histidine / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D051379:Mice; D018625:Microscopy, Atomic Force; D032446:Myoblasts / Q000187:drug effects; D009983:Orthopedic Equipment; D000071228:Polyelectrolytes / Q000737:chemistry*; D011109:Polymethacrylic Acids / Q000737:chemistry; D019736:Prostheses and Implants / Q000592:standards; D011474:Prosthesis Design; D058525:Quartz Crystal Microbalance Techniques; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*
chemical_list: D055396:Bone Morphogenetic Protein 2; D020099:Coated Materials, Biocompatible; D000071228:Polyelectrolytes; D011109:Polymethacrylic Acids; C030613:polymethacrylic acid; D006639:Histidine; D014025:Titanium