Fabrication and biological application of nano-hydroxyapatite (nHA)/alginate (ALG) hydrogel as scaffolds

Abstract

We have fabricated tubular hydrogel scaffolds of nano-hydroxyapatite (nHA)/alginate (ALG) via a layer-by-layer (LbL) technique. Using Ca 2+ as a crosslinker, nHA was assembled with ALG to form a hydrogel network. The inner diameter of scaffolds could be controlled from 0.5 mm to 7 mm by varying the assembled layer numbers of nHA/ALG pairs. By changing the nHA concentration, we can also control the crosslinking degree of the hydrogel network, and further change the mechanical properties, swelling behavior, permeability and diffusivity of the scaffolds. The elastic modulus of the hydrogel scaffolds was regulated from 0.98 AE 0.05 MPa to 2.78 AE 0.08 MPa as the concentration of nHA was changed from 50 mg mL À1 to 300 mg mL À1 , which reached the requirements of avascular soft tissue. The diffusion coefficient was tuned from 23.84 Â 10 À7 cm 2 s À1 to 9.92 Â 10 À7 cm 2 s À1 for controlled mass transport in the hydrogel network. Moreover, human embryo skin fibroblast (ESF) culture experiments prove that nHA can improve cellular adhesion on the hydrogel surface. These results thus suggest that the assembled nHA/ALG hydrogel scaffolds are an attractive biomaterial for great potential application in soft tissue engineering.

Alginate-nanohydroxyapatite hydrogel system: Optimizing the formulation for enhanced bone regeneration

“…Water-swelling characteristics of composites play an important role in the absorption of body fluids and transfer of cell nutrients and metabolites [39,40]. The interactions of carboxyl (-COOH) and hydroxyl (-OH) groups of the polymeric network with water molecules, leads to their diffusion into the hydrogel driven by the osmotic pressure [17]. However, the water-swelling content of composites decreased with the inclusion of nanoHA, with a significant impact when nanoHA was added at 70%.…”

“…NanoHA is commonly used in bone tissue regeneration due to its chemical similarity to the inorganic component of the bone matrix and its inherent characteristics such as biocompatibility, osteoinduction, osteocondutive and osteointegration [4,15,16]. Although in some studies nanoHA was already used to reinforce Alg matrixes [14,[17][18][19][20], no studies have yet addressed the systematic influence of nanoHA on alginate-based hydrogel systems, neither the effect of distinct nanoHA amounts on its physic-chemical properties and biological response. This is of the utmost relevance, since the amount of nanoHA within the composition of polymer-based hydrogels is crucial to design an efficient composite for bone tissue regeneration.…”

Molecular Assembly of Polysaccharide‐Based Microcapsules and Their Biomedical Applications

“…The typical Ca‐ALG gelling process can be induced by Ca 2+ ‐mediated G‐block stacking of ALG (egg‐box calcium‐linked junctions). ALG and Ca 2+ can be assembled alternatively on a tube‐like template to make a hydrogel scaffold 35. In our study, porous CaCO 3 is used as an effective “casting” template 36.…”

Conformal polymer coatings for pancreatic islets transplantation

“…In order to visualize polymer coatings by fluorescence microscopy, alginate was modified as reported elsewhere (Du et al, 2011;Strand et al, 2003). Briefly, 20 mg of diclorotriazinil aminofluorescein (5-DTAF) were added to 10 mL of alginate solution (1.0%, w/v) and pH was adjusted to 11 using 1 M NaOH.…”