bioactive glass, silica, calcium phosphate ceramics and hydroxyapatite nanoparticles are class of nanoparticles which are highly common in bone regeneration, other classes are polymeric nanofibers and nanofiber/nanoparticle composite with strong mechanical and desirable chemical properties for bone tissue engineering. scaffolds of above mentioned materials and their interaction with Osteoblasts or differentiation of stem cells to bone cells in context of mentioned matteirals are hot topics in this field.

Hydroxyapatite crystal maybe can attract osteoclasts (100 micro meter) attached that is associated to bone remodeling then form bone protein such as osteopectin or osteocalcin to attract osteoblast (30 micro meter) for bone regeneration. So collocated scaffold property or pore size to filter different cells for osteoid regeneration and attachment is very important.