Assessing the Suitability of Cellulose-Nanodiamond Composite As a Multifunctional Biointerface Material for Bone Tissue Regeneration

Interfacial surface properties, both physical and chemical, are known to play a critical role in achieving long-term stability of cell-biomaterial interactions. Novel bone tissue engineering technologies, which provide a suitable interface between cells and biomaterials and mitigate aseptic osteolysis, are sought and can be developed via the incorporation of nanostructured materials. In this sense, engineered nanobased constructs provide an effective interface and suitable topography for direct interaction with cells, promoting faster osseointegration and anchoring. Therefore, herein we have investigated the surface functionalization, biocompatibility, and effect of cellulose-nanodiamond conjugates on osteoblast proliferation and differentiation. Cellulose nanocrystals (CNC) were aminated through a 3-aminopropyltriethyoxysilane (APTES) silylation, while nanodiamonds (ND) were treated with a strong acid oxidation reflux, as to produce carboxyl groups on the surface. Thereafter, the two products were covalently joined through an amide linkage, using a common bioconjugation reaction. Human fetal osteoblastic cells (hFOB) were seeded for 7 days to investigate the in vitro performance of the cellulose-nanodiamond conjugates. By employing immunocytochemistry, the bone matrix expression of osteocalcin (OC) and bone sialoprotein (BSP) was analyzed, demonstrating the viability and capacity of osteoblasts to proliferate and differentiate on the developed composite. These results suggest that cellulose-nanodiamond composites, which we call oxidized biocompatible interfacial nanocomposites (oBINC), have the potential to serve as a biointerface material for cell adhesion, proliferationand differentiation because of their osteoconductive properties and biocompatibility; furthermore, they show promising applications for bone tissue regeneration.