Fabrication And Evaluation Of Low-substituted Hydroxypropyl Cellulose/Soy Protein Isolate Composite Hydrogel And Composite Sponges

Low-substituted hydroxypropyl cellulose(L-HPC)has good mechanical properties,thermal plasticity,biocompatibility and biodegradability.It has been widely used in the field of medicine,food,thermoplastic film,pharmaceutical tablets and sustained-release preparation processing,while rarely appear as tissue engineering scaffolds.The solubility of L-HPC in alkaline is higher than cellulose and water soluble hydroxyethyl cellulose(HEC).The mechanical strength of HPC materials is similar to the cellulose materials,and the mechanical strength and water-resistance of HPC materials is higher than that of HEC materials.Because of the steric hindrance of hydroxypropyl,the molecular structure of HPC is more homogeneous than HEC.The free hydroxyl group can be chemically modified as reaction group.Soy protein isolate(SPI)is a plant protein from soy protein.It could be easily biodegraded.The molecular chain contains some active groups such as amino and carboxyl groups,which can be used for chemical reactions.Therefore,we prepared the three-dimensional structure composite materials with L-HPC and SPI as the main raw materials.The structure and physicochemical properties of the L-HPC/SPIC composites were characeterized by methods of polymer chemistry and physics.The cytocompatibility,biocompatibility and hemocompatibility of the composites were investigated by in vitro and in vivo experiments.The main content of this thesis are as following:(1)Fabrication and evaluation of low-substituted hydroxypropyl cellulose/soyb protein isolate composite hydrogel:Using L-HPC and SPI as raw materials,epoxy chloropropane(ECH)as cross-linking agent,a series of L-HPC/SPI composite hydrogel(EHSG-n,n is the SPI percent in the total mass of material content)were prepared by gelation at room temperature.The structure,physical and chemical properties of EHSGs were characterized by Fourier transform infrared spectroscopy(FTIR),X-ray diffraction(XRD),scanning electron microscopy(SEM)and thermosgravimetric analysis(TGA).The results showed there was interaction between L-HPC and SPI,and the content of SPI affected the physicochemical properties of the composite hydrogel.The cytocompatibility and hemocompatibility of the composite hydrogel were evaluated by in vitro cell culture and blood contacting experiments.The results indicated that the composite hydrogel had no cytotoxicity,and SPI improved the adhesion and proliferation of cells.The hemocompatibility experiments displayed that the composite hydrogels had certain anti-clotting properties and hemocompatibility.The results of in vivo implantation experiment indicated that the composite hydrogels had good water resistance,compressive strength and histocompatibility without obvious inflammatory response.(2)Fabrication and evaluation of low-substituted hydroxypropyl cellulose/soy protein composite sponges:Using L-HPC and SPI as raw materials,epoxy chloropropane(ECH)as cross-linking agent,a series of L-HPC/SPI composite hydrogel(EHSG-n,n is the SPI percent in the total mass of material content)was prepared by fast freezing and freeze-drying before gelation.The physical and chemical properties of the sponges were investigated by FTIR,XRD,SEM,water absorption ratio measurement,TGA and compressive testing.The results showed there was interaction between L-HPC and SPI.Because L-HPC is cellulose ether with active hydroxyl groups,the extended side chains reduced the regularity of the molecules,increased the activity of the molecular chain which facilitated the cross-linking with SPI.SPI significantly improved the pore structure and hydrophilicity.As a result,the EHSSs had good strength in wet state.The cytocompatibility and hemocompatibility of the composite sponges were evaluated by in vitro cell culture and blood contacting experiments.The results showed that the composite sponges had good cytocompatibility,especially the EHSS-30,EHSS-50 and EHSS-70.A certain SPI could promote the adhesion,growth,and proliferation of cells and enhance the cytocompatibility of composite sponges.The hemocompatibility experiments displayed that EHSS-n composite sponges had good hemocompatibility and anti-platelet adhesion function.The results of in vivo implantation indicated that composite sponges displayed good biocompatibility and SPI could accelerate the degradation speed of the composite sponges.In a conclusion,the structurally stable low-substituted hydroxypropyl cellulose/soy protein composites could be fabricated by chemical crosslinking of L-HPC and SPI,which combined the characteristics such as mechanical strength,biological safety,biocompatibility and biodegradability of the neat L-HPC and SPI.This work widens the application of HPC and SPI in biomedical materials,for example,using as scaffolds or implanted materials.