Study On Fabrication And Properties Of Bioglass Composite Hydrogels

Bioglass,or bioactive glass,is a type of biomaterial in regenerative medicine,which gave birth to the field of bioactive inorganic material.Bioglass can enhance the deposition of bone-like apatite in the body fluid and stimulate positive cell behaviors,and it has achieved a wide range of clinic applications.However,bioglass particles tend to move and get lost in vivo,and bioglass bulks or scaffolds are impractical in some clinical situations.Those facts limited the further application of bioglass beyond hard tissue repair.Hydrogel possesses a high water-content that similar to body tissues,which contribute to its biocompatibility.The hydrogel can even achieve injectability and in situ gelation by regulating the gelling process.Thus,the combination of bioglass and hydrogel has the potential to be a novel,bioactive and practical biomaterial.Furthermore,bioglass is capable of regulating the chemical microenvironment of fluids by releasing ionic products and generating an alkaline signal,and those features can be utilized to regulate the gelling process of hydrogels.According to above discussion,we designed and prepared bioglass composite hydrogels with the advantages from both sides.Bioglass composite hydrogels in this thesis are bioactive same as the bioglass,besides,they demonstrated new useful features,such as thermosensitivity,in situ gelation and functionalization.In the first chapter,we discussed biomaterials in regenerative medicine,then introduced the advantages and applications of bioglass as a biomaterial.After analyzed the limitation of bioglass,we proposed the topic and main content of the thesis.In the second chapter,we combined bioglass 45S5(BG)and alginate(ALG)into hydrogel beads by calcium crosslinking.BG/ALG hydrogel showed a favorable in vitro bioactivity by inducing bone-like apatite formation and stimulate cell behaviors.Furthermore,we investigated the application of BG/ALG composite hydrogel as cell carriers,and the results showed that BG/ALG enhanced the cell proliferation and osteogenic differentiation of encapsulated cells.In the third chapter,we designed a novel thermo sensitive BG/AGA-ALG(BG/AA)system by introducing agarose(AGA)into BG/ALG,which realized the in situ gelation around physiological temperature.BG could further strengthen the hydrogel networks by releasing cross-linking calcium ions.BG/AA hydrogel showed bioactivity by stimulating in vitro cell migration and in vitro angiogenesis.In the animal study,BG/AA hydrogel promoted the formation of blood vessels and epithelium in the chronic wounds,which further enhanced the chronic wound healing.In the fourth chapter,we designed an in situ gelling system that trigged by the alkaline signal from BG.The cross-link points are imine bonds that formed from the Schiff base reaction between amino and aldehyde groups,which is sensitive to the alkaline signal.Elastin-like polypeptide(ELP)was chosen to realize the design.We introduced the amino and aldehyde groups into ELP polymer chains by genetic engineering and chemical modification.The alkaline signal from BG can then trigger the gelling process of ELP networks.BG/ELP hydrogel showed thermosensitivity and in situ gelation around physiological temperature.Furthermore,we functionalized BG/ELP hydrogel with cell binding motif RGD since ELP is fully designable.BG/ELP hydrogels with RGD promoted cell adhesion and spread.In conclusion,bioglass composite hydrogels have great potential as a biomaterial in regerative medicine.