Preparation And Preliminary Application Of Hydrogel Microspheres Based On Gelatin And Glycosaminoglycans

At present,the research has made a great breakthrough on microspheres.Different devices and chemical cross-linking methods can be used to prepare microspheres.However,it is challenging to prepare hydrogel microspheres with uniform particle size and biocompatibility using natural biomacromolecules as raw materials.In this study,natural biomacromolecules modified with double bonds such as methacrylated gelatin(GelMA),methacrylated hyaluronic acid(HAMA)and methacrylated heparin(HepMA)were used as matrix materials.A series of hydrogel microsphere materials with uniform particle size,good physical stability and biocompatibility were prepared by photocrosslinking method using a microfluidic device.Its potential applications in bone defect repair,adsorption of growth factors in stem cell supernatant,and cell proliferation promotion have been preliminarily evaluated.(1)In order to solve the shortcomings of the existing bone repair materials,such as complex preparation process,non-uniform particle size,poor biocompatibility and degradability,and high price,a hydrogel microsphere for repairing bone defects thereof was provided.The GH hydrogel microspheres for repairing bone defects have been prepared by using microfluidic technology and the principle of photocrosslinking with methacrylated gelatin(GelMA)and nano-hydroxyapatite(n HAP)as raw materials.Its diameter was between 300 and 500 μm,with controllable particle size,stable physical and chemical properties,rough and porous surface,and good biocompatibility,which could promote the proliferation,adhesion and differentiation of MC3T3-E1 cells.The results of alkaline phosphatase assay and alizarin red staining showed that the hydrogel microspheres added with n HAP can enhance the osteogenic differentiation ability of MC3T3-E1 cells in vitro.In addition,the results of animal experiments in vivo showed that compared with the no-implant group,the hydrogel microspheres sample group prepared by us had a significant effect on the repair of bilateral bone defects in rabbits.Therefore,the GH microspheres had an excellent ability to repair bone defects.(2)In addition,the microfluidic technology was also used to prepare HH hydrogel microspheres that adsorbed growth factors in the supernatant of stem cells using methacrylated hyaluronic acid(HAMA)and methacrylated heparin(HepMA)as raw materials.Its diameter was distributed between 100～300 μm,the particle size was uniform,the physical and chemical properties were stable,the surface was rough and porous.Also,it could be photocrosslinked and had a strong negative charge.The precursor material of HH hydrogel microspheres could achieve stable cross-linking when exposed to UV light in a microfluidic device to prepare microspheres.What’s more,the microspheres exhibited an excellent ability to adsorb growth factors.Considering that the therapeutic effect of stem cells was mainly achieved through its autocrine and paracrine various growth factors,the microspheres provided in this study solved the serious problems of stem cells,such as short survival time,decreased viability and potency over time.HAMA and HepMA were biodegradable and strongly negatively charged photocrosslinked hydrogel raw materials,which could realize the adsorption and slow release of growth factors.Through cell experiments in vitro,it was found that the hydrogel microspheres had good biocompatibility and could provide more space for cell proliferation.Moreover,it showed a better effect of promoting cell proliferation after co-culture with cells for a long time.As expected,it had broad application prospects.