Hosted by: Anibal Boscoboinik

Center for Functional Nanomaterials Seminar Effect of pH on polyelectrolyte multilayer formation and growth factor release for orthopedic applications Amy M. Peterson Leonard P. Kinnicutt Assistant Professor Department of Chemical Engineering Worcester Polytechnic Institute Wednesday, May 27, 2015 10:00 a.m. Bldg. 735 â€" Conference Room A Abstract: Because of its strength, durability, and biocompatibility, titanium is a widely used material for orthopedic implants. However, its insufficient integration with the surrounding bone tissue regularly leads to implant loosening and premature implant revision. A promising solution to improve integration is to modify the implant surface chemistry and topography by coating it with a protein-eluting polyelectrolyte multilayer (PEM) coating. 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 (PLH) and poly(methacrylic acid) (PMAA) were built on the BMP-2 layer. The effect of the solutions' pH during the deposition process was investigated. High levels of BMP-2 released over several months were achieved. Approximately 2 μg/cm² of BMP-2 were initially adsorbed on the anodized titanium and a deposition pH-dependent release behavior was observed under physiological conditions. More stable coatings were assembled at pH values corresponding to the closed state of the polyelectrolyte complex. Three different diffusion regimes could be determined from the release profiles: an initial burst release, a sustained release regime and a depletion regime. Mass adsorption monitoring using quartz crystal microbalance with dissipation monitoring (QCM-D) showed that PLH was adsorbed in greater quantities than PMAA