Hybrids of Silica/Poly(caprolactone coglycidoxypropyl trimethoxysilane) as Biomaterials

Bioactive glasses stimulate bone regeneration but are brittle. Biomaterials are needed that share load with bone, promote bone regeneration, and biodegrade at controlled rates. Sol-gel hybrids can achieve this through their intimate inorganic and organic conetworks, depending on the organic polymer used. Polycaprolactone degrades slowly but lacks functional groups for the critical step of covalent coupling to the silica conetwork. Here, we synthesized a novel copolymer of caprolactone and glycidoxypropyl trimethoxysilane through one-pot ring opening polymerization (ROP). Hybrids with different organic content were fabricated using such a copolymer for the first time. The copolymer can directly bond to a silica network due its trimethoxysilane groups, which can hydrolyze, leaving silanol groups that undergo polycondensation with silanol groups of the silica network. The number of repeating units of caprolactone and glycidoxypropyl trimethoxysilane functional groups were controlled via ROP. The mechanical properties of the hybrids were tuned by weight percent and the number of repeating units of caprolactone independently, producing a homogeneous material with high strength (64 MPa) and strain to failure (20%) that deformed in a unique linear elastic manner until failure. MC3T3-E1 preosteoblast cells adhered to the hybrids. Introducing such a copolymer created a new way to fabricate covalently bonded polycaprolactone/silica hybrids for future bone repair.