Mineralized biomimetic collagen/alginate/silica composite scaffolds fabricated by a low-temperature bio-plotting process for hard tissue regeneration: fabrication, characterisation and in vitro cellular activities

Abstract

The natural biopolymers, collagen and alginate, have been widely used in various tissue regeneration procedures. However, their low mechanical and osteoinductive properties represent major limitations of their usage as bone tissue regenerative scaffolds. To overcome these deficiencies, biomimetic composite scaffolds were prepared using a mixture of collagen and alginate as a matrix material, and various silica weight fractions as a coating agent. The composite scaffolds were highly porous (porosity > 78%) and consisted of interconnected pores, with a mesh-like structure (strut diameter: 342-389 mm; average pore size: 468-481 mm). After incubation in a simulated body fluid, various levels of bone-like hydroxyapatite (HA) on the surface of the composite scaffolds developed in proportion to the increase in the silica content coating the scaffolds, indicating that the composite scaffolds have osteoinductive properties. The composite scaffolds were characterised in terms of various physical properties (water absorption, biodegradation and mechanical properties, etc.) and biological activities (cell viability, live/ dead cells, DAPI/phalloidin analysis, osteogenic gene expression, etc.) using pre-osteoblasts (MC3T3-E1).The mechanical improvement (compressive modulus) of a composite scaffold in compressive mode was $2.4-fold in the dry state compared to the collagen/alginate scaffold. Cell proliferation on the composite scaffold was significantly improved by $1.3-fold compared to the mineralised collagen/ alginate scaffold (control). Osteocalcin levels of the composite scaffold after 28 days in cell culture were significantly enhanced by 3.2-fold compared with the control scaffold. These results suggest that mineralised biomimetic composite scaffolds have potential for use in hard tissue regeneration.

A space network structure constructed by tetraneedlelike ZnO whiskers supporting boron nitride nanosheets to enhance comprehensive properties of poly(L-lacti acid) scaffolds

“…It indicated that the addition of BNNSs and T-ZnO w into PLLA scaffolds was beneficial to hBMSCs proliferation and differentiation, which played a critical role in new bone formation and growth. One possible reason for the improved cell proliferation and differentiation was that the addition of BNNSs into scaffold was beneficial for the expression of several essential cell adhesion proteins (such as fibronectin or vitronectin) during cell culture, which promoted cell adhesion and further increased cell proliferation and differentiation 69 70 . A recent study had shown that BN could result in an increase in the Runx2 gene expression level, indicating the increased osteogenic differentiation 67 .…”

Alginate/Nanohydroxyapatite Scaffolds with Designed Core/Shell Structures Fabricated by 3D Plotting and in Situ Mineralization for Bone Tissue Engineering

“…The mixed alginate/ HAP scaffolds had lower water adsorption capability compared to pure alginate and mineralized alginate scaffolds because the HAP particles mixed into the alginate paste occupied some space within the matrix and therefore decreased the ability for water adsorption. 38 The plotted alginate and mineralized scaffolds presented here have significantly higher mechanical strength than those fabricated with low concentrated alginate by either 3D plotting or conventional methods. 24 There are many studies demonstrating the influence of surface properties of scaffolds on cell attachment and shape, 43−46 especially chemical composition and morphology.…”

3D Bioprinting for Musculoskeletal Applications

“…In the literature, naturally-derived biomaterials such as alginate [10,11], collagen [11], gelatine and fibrin [12], have successfully promoted cell adhesion, proliferation and osteochondral differentiation with both cell-free and cell-laden printing approaches. However, natural materials were the most common materials used for cell-laden printing (70% of total reported in literature, Fig 3B) for musculoskeletal applications.…”