Bio-inspired synthesis of a hierarchical self-assembled zinc phosphate nanostructure in the presence of cowpea mosaic virus: in vitro cell cycle, proliferation and prospects for tissue regeneration.

Self-assembly is an important auto-organization process used in designing structural biomaterials which have the potential capability to heal tissues after traumatic injury. Although various materials having the ability to heal after injury are available, there is still a substantial need to develop new improved materials. To address this issue, we have developed hierarchical three-dimensional (3D) self-assembled zinc phosphate (Zn3 (PO4 )2 ) in the presence of cowpea mosaic virus (CPMV). Zn3 (PO4 )2 nanoparticles are self-assembled into nanosheets with a high degree of isotropy and then self-organized into a 3D structure that can enhance surface interactions with biological entities. The self-assembled structure is formed through the auto-organization of nanoparticles of size ∼50 nm under the influence of CPMV. The cellular response of self-assembled Zn3 (PO4 )2 and cell-particle adhesion behavior have been investigated through in vitro studies using modeled osteoblast-like MG63 cells. Self-assembled Zn3 (PO4 )2 resulted in proliferation of MG63 cells of up to 310% within 7 days of incubation. A 15% higher proliferation was obtained than with commercially available hydroxyapatite (HAp). Immunofluorescent analysis of MG63 cells after co-culturing with self-assembled Zn3 (PO4 )2 confirmed the healthy cytoskeletal organization and dense proliferation of MG63 cells. Further, Zn3 (PO4 )2 exhibited ∼28% cell-cycle progression in S phase, which is higher than obtained with commercially available HAp. Overall, these results demonstrate the multiple functions of hierarchical self-assembled Zn3 (PO4 )2 in the regeneration of bone tissue without defects and increasing the formation of cellular networks, and suggest its use in bone tissue engineering.