Amino−Polysiloxane Hybrid Materials for Bone Reconstruction

Organic−inorganic hybrid materials containing amino functional groups were prepared as monoliths and their in vitro bioactivity and degradation were investigated using a simulated body fluid (SBF). The amino−polyorganosiloxane hybrids were obtained via sol−gel starting from N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (DAMO). With the addition of γ-methacryloxypropyl-trimethoxysilane (MPS), hydrolytically stable and flexible polyorganosiloxane networks were obtained. To induce bioactivity, we added calcium to the hybrids as a calcium salt during the synthesis. A nanocrystalline apatite-like phase was formed on the hybrid surfaces after being soaked in SBF. The bioactivity and degradability of calcium-containing hybrids increased as the DAMO:MPS molar ratio increased, because the molar ratio affects both the functional groups and the charge of the hybrid surfaces, as well as the rate of Ca2+ release to the SBF solution. Zeta-potential (ζ) measurements revealed that at physiological pH, the net surface charge of the bioactive hybrids was negative because of a Si−O- group density higher than that of protonated amino groups (NH3+ and NH2+). These new materials are a promising alternative in bone tissue regeneration because of their tailored in vitro bioactivity and degradability and the presence of amino groups that are able to interact with biological entities.