Exposed Hydroxyapatite (HA) Particles on the Surface of Photo-crosslinked Poly(ε- caprolactone)/HA Nanocomposites and Promoted MC3T3 Cell Responses

摘要

Developing a biodegradable and crosslinkable polymer scaffolds with incorporated hydroxyapatite (HA), the major inorganic component of bone mineral having excellent biocompatibility and osteoconductivity, is the crucial task in bone regeneration applications. Photo-crosslinkable poly(ε-caprolactone fumarate)s and poly(propylene fumarate) have been used to form nanocomposites with HA to achieve enhanced mechanical properties and cellular functions. However, the amount of HA that can actually be exposed on the surface of the polymer and interact with cells is still largely unknown. In this study, one amorphous and one crystalline poly(ε-caprolactone) diacrylates (PCLDAs)/HA nanocomposites have been developed and compared between their original and cut forms to investigate the amount of HA on the surface of the network systems. PCLDA530 and PCLDA2000 with nominal molecular weight of their PCL diol precursors of 530 and 2000 have been photo-crosslinked with HA compositions of 0%, 10%, 20% and 30%. The mechanical properties were greatly enhanced by HA nanoparticles. Semi-crystalline PCLDA2000/HA nanocomposites showed significantly more exposed HA on the surface after cutting while less HA is buried in amorphous PCLDA530/HA. Mouse MC3T3 cell proliferation has been enhanced strongly with increasing the HA composition via the role of bioactive HA and surface stiffness. More exposed HA on the surface of cut PCLDA2000/HA nanocomposites result in better hydrophilicity and significantly faster MC3T3 cell proliferation.