Biomimetic patterning of polymer hydrogels with hydroxyapatite nanoparticles

We report here an in situ process to produce nano-composite polymer hydrogels having surfaces patterned with hydroxyapatite (HA) nanoparticles (100 nm). Poly (vinyl alcohol) (PVA) has been used as a hydrogel forming medium. A three step process, comprising precipitation of HA nanoparticles in presence of PVA molecules and freeze thawing of obtained PVA-HA emulsion, followed by critical point drying, has been devised to produce three dimensional nanocomposite hydrogels. Interaction of Ca2+ with oxygen atoms of PVA and the hydrogen bonding characteristic of the polymer have been exploited to have controlled size distribution of HA in a continuous and macroporous network of PVA. A systematic variation in the polymer concentration could be correlated with microstructural features of the hydrogel.