3D Bioplotting of Gelatin/Alginate Scaffolds for Tissue Engineering:Influence of Crosslinking Degree and Pore Architecture on Physicochemical Properties

Gelatin/Alginate hydrogels were engineered for bioplotting in tissue engineering. One major drawback of hydrogel scaffolds is the lack of adequate mechanical properties. In this study, using a bioplotter, we constructed the scaffolds with different pore architectures by deposition of gelatin/alginate hydrogels layerby-layer. The scaffolds with different crosslinking degree were obtained by post-crosslinking methods. Their physicochemical properties, as well as cell viability, were assessed. Different crosslinking methods had little influence on scaffold architecture, porosity, pore size and distribution. By contrast, the water absorption ability, degradation rate and mechanical properties of the scaffolds were dramatically affected by treatment with various concentrations of crosslinking agent （glutaraldehyde）. The crosslinking process using glutaraldehyde markedly improved the stability and mechanical strength of the hydrogel scaf- folds. Besides the post-processing methods, the pore architecture can also evidently affect the mechanical properties of the scaffolds. The crosslinked gelatin/alginate scaffolds showed a good potential to encap-sulate cells or drugs.

Liquid-phase 3D bioprinting of gelatin alginate hydrogels:influence of printing parameters on hydrogel line width and layer height

Extrusion-based 3D bioprinting is a direct deposition approach used to create three-dimensional(3D)tissue scaffolds typically comprising hydrogels.Hydrogels are hydrated polymer networks that are chemically or physically cross-linked.Often,3D bioprinting is performed in air,despite the hydrated nature of hydrogels and the potential advantage of using a liquid phase to provide cross-linking and otherwise functionalize the hydrogel.In this work,we print gelatin alginate hydrogels directly into a cross-linking solution of calcium chloride and investigate the influence of nozzle diameter,distance between nozzle and surface,calcium chloride concentration,and extrusion rate on the dimensions of the printed hydrogel.The hydrogel layer height was generally found to increase with increasing extrusion rate and nozzle distance,according to the increased volume extruded and the available space,respectively.In addition,the hydrogel width was generally found to increase with decreasing nozzle distance and cross-linking concentration corresponding to confinement-induced spreading and low crosslinking regimes,respectively.Width/height ratios of^1 were generally achieved when the nozzle diameter and distance were comparable above a certain cross-linking concentration.Using these relationships,biocompatible 3D multilayer structures were successfully printed directly into calcium chloride cross-linking solution.