| As the most abundant biopolymer in the nature, cellulose has been used widely in various industries and fields. With good biocompatibility, cellulose has been utilized in the biomaterial field for a long time. However, the lack of cellulose enzyme in human body makes it is unable to realize cellulose's actual degradation in vivo, which restricted its application as biodegradable implantation. Hydroxyethyl cellulose (HEC) is a kind of cellulose derivative by using cellulose as raw material through alkalization and etherification process, which could be easily dissolved in water. With good properties of thickening, suspension, dispersion, emulsification, adhesion, film-forming, protection of water and colloids, HEC has been widely used in the fields of oil, paint, architecture, textile, papermaking, food, and medicine, etc. HEC itself has no acidic and basic groups as well as neurotoxicity, which could be decomposed into monosaccharide and fully absorbed by human body, showing good biocompatibility. Thus, HEC not only has some excellent properties of cellulose, but also has in vivo degradation performance that cellulose does not have, so the development of new biomaterials based on has important theoretical significance and potential applications.Soy protein isolate (SPI) is an abundant natural polymer with edibility and biodegradability. Its application in the biomaterial field has just started. SPI was derived from plants, so the transmission of animal diseases could be avoided, and its degradation products has no toxic side effects on cells but could even promote cell proliferation and tissue regeneration. Meanwhile, SPI has many biological activities, for example, can lower cholesterol and promote the differentiation and growth of osteocyte, reduce the risk of cardiovascular disease and some cancers, etc. The good degradability, biocompatibility and a variety of biological activity characteristics fix a good foundation for its application in the field of biomedical materials. In addition, with a good processing performance, SPI can be made into various materials such as films, gels, sponges and fibers by dissolving or thermoplastic processing. As a biomaterial, SPI has been used in the areas of the drug release, wound dressings and scaffold materials. Further research and development of SPI-based biomaterials can not only enrich the kinds of biomaterials, but can also greatly improve its added value, so it is worthy of in-depth and systematic study.HEC and SPI was used as the main raw materials in this thesis, which were crosslinked with epichlorohydrin (ECH) or ethylene glycol diglycidyl ether (EDGE) with epoxy groups to fabricate HEC/SPI composite films and sponges. Firstly, a series of HEC/SPI-based films were fabricated and their physical and chemical properties and biocompatibility were systematically evaluated; Secondly, a series of HEC/SPI-based sponges with porous structure and high permeability were fabricated, and their potential function as a wound dressing was revealed by animal experiment; Thirdly, the shape memory characteristics and recoverability after contacted with water of the HEC/SPI-based sponges were investigated by using as filling material for soft tissue repairing in vivo through subcutaneous filling experiment; Fourthly, a series of nerve conduits with different inner channels from the HEC/SPI-based sponges were constructed and their repair function for peripheral nerve defect was evaluated by animal experiments; Finaly, By, a series of polypyrrole-containing HEC/SPI-based sponges were prepared by in situ polymerization of pyrrole, and effects of the main factors on the conductivity of the sponges were studied. The main contents of this thesis include the following several aspects:(1) Preparation and biocompatibility evaluation of HEC/SPI composite films:A series of HEC/SPI composite films was fabricated using HEC and SPI as main raw materials and ECH as crosslinker through the process including blending, casting and drying. The structure and physical properties of the films were characterized by Fourier Transform infrared spectroscopy(FTIR), X-ray diffraction (XRD), solid-state 13C NMR,, scanning electron microscopy (SEM), UV-vis spectroscopy, water uptake ratio and moisture absorption ratio testing, in vitro degradation experiment and mechanical testing. The cytocompatibility of the films was evaluated by MTT and cell culture experiment. The hemocompatibility of the films was evaluated through platelet adhesion, plasma recalcification time and hemolysis ratio testing assays; The biodegradability and in vivo biocompatibility of the films were evaluated through implantation experiment in rats. The results indicated that the ECH-crosslinked HEC/SPI composite films exhibited controllable water uptake performance, transparency, mechanical properties, good biodegradability and biocompatibility, showing potential application as biomaterials.(2) Preparation and biocompatibility evaluation of HEC/SPI composite sponges and their applications as wound addressing:A series of HEC/SPI composite sponges was fabricated using HEC and SPI as main raw materials and EDGE as crosslinker through the process including blending, casting and freeze-drying. The structure and physical properties of the sponges were characterized by FTIR, XRD, solid-state 13C NMR, SEM, water uptake ratio and water retention ratio testing, and compression performance testing. The cytocompatibility of the sponges was evaluated by MTT and cell culture experiment. The hemocompatibility of the films was evaluated by MTT and direct cell culture experiments. The hemocompatibility of the sponges was evaluated through routine blood coagulation, whole blood incubation experiment and hemolysis ratio testing assay. The potential of the sponges as wound dressing for skin was evaluated by animal skin repairing experiment. The results showed that the EDGE-crosslinked HEC/SPI composite sponges exhibited homogenous porous structure, good water uptake and water retention performance, mechanical properties and biocompatibility as well repair performance for skin defect, whose repairing efficiency was better than that of medical gauze.(3) Preparation of HEC/SPI composite sponges with shape memory characteristics and their application as filling and implantation for soft tissue defect. Effects of the main factors such as pressure, temperature, hot-pressing and cycles on the shape memory property and recovery degree of the sponges after water-contacting were investigated. The structure and physical properties of the sponges were characterized by FTIR, XRD, SEM, and water uptake ratio testing. The cytocompatibility of the sponges was evaluated by MTT and direct cell culture experiments. The potential applications of the sponges were revealed by subcutaneous filling and implantation experiment in rats. The results showed that the deformation of composite sponges under the condition of single pressure was recoverable; The deformation degree of the sponges was very little under the condition of single temperature and created little influence on the volume of sponge. The sponges were able to recover in a certain range of temperature and pressure during the hot-pressing process. The result of subcutaneous filling and implantation experiment in rats showed that the composite sponges exhibited the filling and repairing function for soft tissue defect.(4) Construction of multi-channel nerve guide conduits from HEC/SPI composite sponges and their application for the repair and regeneration of peripheral nerve defect in rats:A series of nerve guide conduits with 1,3 and 7 inner channel were constructed from HEC/SPI composite sponges and applied to bridge and repair the sciatic nerve defect in rat model. The results from SEM observations showed that the channels were uniformly distributed with the pore structural sponges. For the nerve repair in rats, regenerative nerve formed and the nerve fiber bundles arranged relatively orderly confirmed by HE staining and fluorescence double standard observation 3 months after the nerve defect bridges were operated. From the results of toluidine blue staining assay and transmission electron microscope (TEM) observation, a large number of regenerated myelinated nerve fibers formed, and the repairing efficiency of the nerve conduits with 3 or 7 channels was superior to those with single channel. Through muscle masson trichromatic dyeing and muscle slitting and SEM observation, the results showed that the shrinked muscles got a certain degree of recovery through the catheter bridge repairing. The recovery degree of muscles in the group with 3 or 7 channels was higher than that in the group with single channel. Thus, the multi-channel HEC/SPI composite sponges exhibited certain repairing function on the defected peripheral nerve, and the repair efficiency of the nerve conduits with 3 and 7 channels was better than those with single channel.(5) Preparation and biocompatibility evaluation of polypyrrole-containing HEC/SPI composite sponges by in situ polymerization of pyrrole. A series of polypyrrole-containing HEC/SPI composite sponges were prepared by suing HEC/SPI sponges as matrix through in situ polymerization of pyrrole, to endow the electrical conductivity. The structure and physical properties of the conductive composite sponges were characterized by FTIR, XRD, SEM, TEM and compression performance testing. The cytocompatibility of the sponges was evaluated by MTT and direct cell culture experiments. The hemocompatibility of the sponges was evaluated through routine blood coagulation, hemolysis ratio testing and blood cell incubation experiment assays. The results showed that the mechanical strength of sponge materials was improved and their structure remained almost unchanged by in situ polymerization pyrrole. The composite sponges not only exhibited good original biocompatibility, but also had electrical conductivity, providing the potential for the development of novel conductive polymer composite sponges.To sum up, a series of HEC/SPI composite films and sponges were prepared successfully in this thesis. The structure and physical properties of the films and sponges were characterized through polymer physical and chemical methods. The biocompatibility, hemocompatibility and histocompatibility of the films and sponges was systematically evaluated by in vitro cell culture experiments and blood-contacting assays as well as in vivo animal implanting experiments. The results indicated that the composite films and sponges exhibited good biocompatibility with potential as wound address for skin repair, as filling materials for soft tissue reparir, and nerve conduit for peripheral nerve defect. In one word, present thesis indicated that these new HEC/SPI-based films and sponges showed potential applications as biomaterials in the tissue engineering field, providing a theoretical significance and experimental support for the future application. |
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