(540b) Polyelectrolyte Complex for pH-Controlled Release of Proteins From Surfaces

Titanium is a popular choice for implant material given its strength, durability, and biocompatibility; however, strong interfaces between unmodified titanium and the surrounding tissue are not achieved, resulting in stress shielding and implant loosening. Many surface parameters have been investigated for improving biointerfaces. Topographical features play a significant role in cell shape and behavior. Additionally, growth factors play key roles in regulating osteoblast behavior and osteoid and bone formation. One option for improving achieving better adhesion is coating the titanium surface with a protein-eluting polyelectrolyte complex. Morphogenetic proteins such as BMP-2 have been shown to cause cell migration, expression of different genes, and development of different tissues. A biocompatible polyelectrolyte coating was prepared and was shown to be effective for sustained release of microgram-levels of charged species under physiological conditions. This complex demonstrated pH-dependent release, with maximum release at pH = 5-6, but low levels of sustained release under physiological conditions. Smaller initial burst release and higher amounts of sustained release were observed when a lower molecular weight polyanion was used.