Tailoring hierarchical meso–macroporous 3D scaffolds: from nano to macro

Abstract

Bone tissue regeneration requires the use of 3D scaffolds which mimic the architecture of the natural extracellular matrix, creating an adequate microenvironment for bone cell growth. Such 3D scaffolds need surface properties suitable to biological recognition in the early stage of cell adhesion, necessary to assure complete cell colonization, retained cell functionality, and subsequently bone regeneration. Herein, hierarchical 3D scaffolds based on new hydroxyapatite/mesoporous glass nanocomposite bioceramic (MGHA) exhibiting different scales of porosity have been synthesized. These possess: (i) highly ordered mesopores with diameters of 10 nm; (ii) macropores with diameters in the 30-80 µm range with interconnections of 1-10 µm; and (iii) large macropores of ca. 500 µm. To improve their surface properties, 3D scaffolds were modified through direct functionalization with amine propyl groups, which notably improves preosteoblast adhesion, proliferation (2.3 fold), differentiation (4.8 fold) and further cell colonization of these scaffolds. The observed enhancement can be related to these amine groups which favour early adhesion, e.g., based on nonspecific protein adsorption as was demonstrated by ellipsometry. These results suggest that the combination of hierarchical structure design and amine surface modification of hydroxypatite/mesoporous nanocomposite scaffolds, yields a double increase in cell proliferation, as well as quadruple increase in cell differentiation, demonstrating the potential of these nanocomposite materials for bone tissue regeneration purposes.

Synthesis and characterization of sol–gel derived calcium hydroxyapatite thin films spin-coated on silicon substrate

“…The CHA coatings should have a high degree of crystallinity, correct stoichiometry and very good adhesion to the substrate [1,12,13]. Cell colonization and bone growth occur when pores are larger than 50-300 µm [2,11,[14][15][16][17].…”

Response of osteoblasts and preosteoblasts to calcium deficient and Si substituted hydroxyapatites treated at different temperatures

“…Under in vitro conditions, the adsorption of these proteins from culture medium determines the early non-specific stage of cell adhesion, facilitating cell spreading on the scaffolds through the formation of a conditioning protein layer that promotes cell adhesion, differentiation and extracellular matrix production [40,41]. and SiHA-1250 adsorb lower amounts of proteins compared with the scaffolds treated at 700ºC.…”

Preventing bacterial adhesion on scaffolds for bone tissue engineering

“…One of the advantages of RC is the possibility to integrate nanostructural features into micro-macrostructure matrices to fine-tune cellular responses. Thus, the use of sol-gel process combined with RC technique, where the sol can be directly printed before gelation in a one-pot procedure, permits the design of hierarchical 3D meso-macroporous [98] . Hence, the versatility of RC allowed the addition of biodegradable polymers into the slurries avoiding high temperature processing and improving its mechanical properties.…”