Controlled Drug Release from Ureasil−Polyether Hybrid Materials

Flexible, transparent, and insoluble urea-cross-linked polyether−siloxane hybrids presenting a tunable drug delivery pattern were prepared using the sol−gel method from PEO (poly(ethylene oxide)) and PPO (poly(propylene oxide)) functionalized at both chain ends with triethoxysilane. Different polyether chain lengths were used to control the urea/siloxane (named ureasil) node density, flexibility, and swellability of the hybrid network. We herein demonstrate that the drug release from swellable hydrophilic ureasil−PEO hybrids can be sustained for some days, whereas that from the unswellable ureasil−PPO hybrids can be sustained for some weeks. This outstanding feature conjugated with the biomedically safe formulation of the ureasil cross-linked polyether-siloxane hybrid widens their scope of application to include the domain of soft and implantable drug delivery devices.