Study On The Preparation And Properties Of Macroporous Composite Hydrogels Based On Emulsion Template

Hydrogel is one of most promising materials to mimic extracellular matrix due to its hydrophilic cross-linking network and aqueous environment to support cell growth.The porous structure of the hydrogel is also important.The three-dimension highly interconnected pores could significantly affect the cell adhesion,proliferation,migration,secretion and tissue ingrowth.Emulsion templating technique is an important tool for the preparation of ordered highly porous materials in biomedical field.In this dissertation,we prepared porous hydrogels with interconnected open-porous structure based on emulsion templates stabilized by different stabilizers.The main research contents and results are as follows:Cellulose nanocrystals(CNCs)have extensive applications in building advanced materials due to its great cell affinity and mechanical strength,but it is difficult to stabilize emulsions because of its high hydrophilicity.A quadruple hydrogen bonding moiety 2-ureido-4[1H]-pyrimidone(UPy)was successfully grafted onto the surface of CNCs via free radical polymerization.Oil-in-water emusion was prepared by UPy modified CNCs(CNC-UPy)via one-step emulsification,macroporous composite hydrogel was obtained after the polymerization of the aqueous phase containing acrylamide and gelatin mathacrylate(GelMA).Differents methods were applied for the characterization of physical and chemical properties.The results indicated that the swelling ratio,pore size and mechanical strength of macroporous hydrogels and size of emulsion droplets' size could be controlled by the concentration of CNCUPy.In vitro cell experiments showed that these highly porous gels were biocompatible to support the adhesion and growth of mouse bone mesenchymal stem cells(BMSCs).Furthermore,a noval air-in-water emulsion,which stabilized by gelatin mathacrylate(GelMA),was used as templates to prepare macroporous hydrogels.Firstly,we added carbon nanotubes(CNTs)in to GelMA emulsion,the results showed that CNTs could absorb GelMA onto surface and promoted the stabilization of the hybrid emulsion as a co-stabilizer.The resulting macroporous hydrogel had great interconnective pores structure and swelling properties,proved the GelMA hybrid air-in-water emulsion templating method was possessed of stronger applicability and generality.Then the Laponite clay was introduced into the air-in-water emulsion stabilized by GelMA to promote osteogenic differentiation.The physicochemical properties of the emulsion and gel were also investigated.The results showed that the addition of clay particles promotes the stability of the emulsions,the emulsion size decreased and mechanical strength of hydrogel increased with clay content increasing.Furthermore,in vitro BMSCs culture assays indicated that the macroporous scaffolds had great cell adhesion,and the addition of clay greatly facilitated the secretion of ALP,which indicated the promising capability of osteogenic differentiation in the absence of any osteoinductive factors.