Preparation And Functional Properties Of Biomedical Materials Based On Chitosan And Alginate

Chitosan, a copolymer of β- (1,4)- 2- acetamido - 2 - deoxy- D- glucose and β-(1,4) -2- amino -2- deoxy -D-glucose units, has attracted considerable interests in the field of wound dressing and tissue engineering due to its good biological activities, biocompatibility and biodegradability. Recent years, a great deal of research had been reported on chitosan's function in improving wound healing and tissue repairing, while most of them are insufficiency. For example, studies on the effect of chitosan and its derivatives against the growth of fiber cells, which is important in wound healing and tissue repairing, are still lack system and integrity. Few study working on the mouth tissue repairing of chitosan especially chitosan derivatives have been reported. How to enhance chitosan's function on wound dressing and hemostasia material and transfer them into actual application is the study focus at all times.Alginate are linear copolymers of β-(1-4)-linked D-mannuronic acid and α-(l-4)-linked L-guluronic acid units. The Alginate fiber can be used to prepare novel wound dressing, which will form gel at wound surface in situ and create a wet healing environment. But the ability of pure alginate in helping wound healing is not high enough. And to the best of our knowledge, few reports are dealing with the combination of alginate salt with other active macromolecule in order to improve alginate fiber's function. One aim of the dissertation is to improve the functionality of alginate wound dressing fiber.In this dissertation, the effect of low molecular weight chitosan, D-glucosamine hydrochloride, N-acetyl-D-glucosamine, carboxymethyl chitosan and water-soluble chitin on the proliferation of human skin fibroblast were studied systematically; And modified chitosan using all kinds of chemical reaction were prepared to optimize structure and properties of them. A series of fibers and non-woven were prepared using blending and wet-spinning technology. The effects of them on wound healing were investigated in order to combine diverse advantages and obtain ideal wounddressing. Novel wound dressing was prepared with distinct structure and properties. And the optimized coagulation solution of alginate and water-soluble macromolecule complex fiber was studied. The effect of N-succinyl chitosan with different molecular weight and low molecular weight chitosan on the proliferation of human periodontal ligament cells were systematically investigated. Carboxymethyl chitosan quaternary ammonium salt was firstly prepared and applied as pulp-capping materials. Carboxymethyl chitosan quaternary ammonium salt's inducement to reparative dentine formation was studied.The main contents and conclusions are summarized as below:1. Effect of chitosan derivatives on the proliferation of human skin fibroblast and the medical wound dressing fiber by blend with alginate: Low weight chitosan, carboxymethyl chitosan and water-soluble chitin with different molecular weight was prepared by degradation, carboxymethylate and acetylate reaction. Effect of all samples above together with D-glucosamine hydrochloride and N-Acetyl-D-glucosamine on the proliferation of human skin fibroblast was studied by MTT method. It was found that low molecular weight chitosan, D-glucosamine hydrochloride and N-Acetyl-D-glucosamine show inhibiting effect to the proliferation of human skin fibroblast. Carboxymethyl chitosan and water-soluble chitin with different molecular weight can promote proliferation of human skin fibroblast. The promoting effect has no relation with molecular weight. Thus, alginate/carboxymethyl chitosan and alginate/water-soluble chitin were prepared to optimize their properties. The method and conclusions are summarized as below:Alginate/carboxymethyl chitosan and calcium alginate/water-soluble chitin blend fibers were prepared through wet spinning. The structure and properties of the blend fibers were studied with the aids of infrared spectra, X-ray diffraction and scanning electron micrography. The strong intermolecular interaction between alginate and chitosan derivatives occurred in the blend fibers. There were good miscibility between aiginate and derivatives molecular due to the strong intermolecular interaction. Through controlling blend condition, blend fiber can obtain a better mechanical andwater absorbency property than pure alginate fiber. The maximum value of water absorbency achieved 398%. The antibacterial fibers were obtained by treated with aqueous solution of chitosan quaternary ammonium salt. The novel wound dressing was prepared with fibers by paper-making method. We found the wound dressing can promote wound healing more effectively than vaseline gauze and pure alginate wound dressing.2. Preparation and properties of chitosan, alginate and water-soluble macromolecule blend fiber: Polymer blend can combine diverse advantages and obtain ideal wound dressing. Chitosan/konjac blend fiber was prepared by wet-spinning. The best coagulation bath is NaOH/ethanol (1/1) solution. The introduction of konjac in the blend fiber can improve water absorbency properties of fiber. The maximum value of tensile strength was observed at 20% konjac content and achieved 12.85cN/tex in the dry state and 5.38cN/tex in the wet state respectively. The best values of breaking elongation in dry state was 24.4% at 10% konjac content and it in wet state was 54.5% at 20% konjac content. The novel wound dressing was prepared with fibers by paper-making method. We found the wound dressing can promote wound healing than vaseline gauze more effective. Through controlling blend condition, the blend wound dressing can obtain a better healing effect than pure chitosan wound dressing.Alginate/gelatin and alginate/ polyvinyl alcohol blend fibers were prepared by spinning their mixture solution through a viscose-type spinneret into a coagulating bath containing aqueous CaCb and ethanol. Ethanol is important to water-soluble macromocular solidification. The introduction of gelatin and polyvinyl alcohol in the blend fiber can improve water absorbency properties of fiber. Through controlling blend condition, blend fiber can obtain a better mechanical property than pure alginate fiber. The antibacterial fibers were obtained by treated with aqueous solution of silver nitrate. The bacteria reduction rate of the treated fibers to Staphylococcus aureus is above 99.9%.3. Hemostatic and antimicrobial properties of chitosan/alginate polyelectrolyte complex sponge: Chitosan/alginate polyelectrolyte complex sponge was prepared by hyophilization, The IR spectra of the samples show that the strong static interactionexist between chitosan and alginate. The apertures of sponge increase with introduction of alginate. The introduction of alginate in the sponge can improve water absorbency properties of sponge. The hemostatic property of chitosan/alginate polyelectrolyte complex sponge is superior to gelatin sponge and gauze. The antibacterial sponges were obtained by introduction silver sulfadiazine and polyvinylpyrrolidone/iodine complex. The sponge loaded with silver sulfadiazine exhibit more persistent antibacterial activities than those loaded with polyvinylpyrrolidone/iodine complex.4. Application of N-succinyl chitosan and carboxymethyl chitosan quaternary ammonium salt in dentistry: N-succinyl chitosan with different molecular weight were prepared using H2O2 degradation. Low weight soluble chitosan with different molecular weight was prepared by enzyme degradation. Their effects on proliferation of human periodontal ligament cells were studied by MTT method. N-succinyl chitosan can dramatically accelerate the growth of human periodontal ligament cells and the procedure was improved with increasing concentration while not affected by molecular weight. Low molecular weight chitosan showed the inhibiting effect to the growth of human periodontal ligament cells.Preparation of carboxymethyl chitosan quaternary ammonium salt and its application in pulp-capping: Carboxymethyl chitosan quaternary ammonium salt was prepared and complex with Ca(0H)2 as pulp-cap. Animal experiment results indicated that carboxymethyl chitosan quaternary ammonium salt can induce reparative dentine formation and showed a better ability in dentin inducing compared to calcium hydroxide group. Carboxymethyl chitosan quaternary ammonium salt can strongly induce reparativedentine formation.The main creative ideas are listed as following:1. The effects of low molecular weight chitosan, D-glucosamine hydrochloride, N-acetyl-D-glucosamine, carboxymethyl chitosan and water-soluble chitin on the proliferation of human skin fibroblast were studied systematically. It was found that carboxymethyl chitosan and water-soluble chitin with different molecular weight can promote proliferation of human skin fibroblast. The promoting effect has no relationwith molecular weight. Alginate blend fibers with carboxmethyl chitosan and water-soluble chitin were prepared. The novel non-woven wound dressing made of above blend fibers;which healing effect is superior to pure alginate wound dressing and vaseline gauze. Blend can improve water absorbency properties and mechanical properties of the fiber.2. The best coagulation bath of alginate and water-soluble macromolecule complex was found out. We discover the introduction of alcohol is important to spinning of alginate alginate and water-soluble macromolecule complex. Alginate/gelatin and alginate/polyvinyl alcohol blend fibers were prepared by wet-spinning. Blend can improve mechanical properties and water absorbency of alginate fibers;and lowed costs of fibers. The antibacterial fibers were obtained by treated with aqueous solution of silver nitrate. The introduction of konjac in the blend fiber can improve water absorbency and mechanical properties of chitosan fiber. The best coagulation bath is NaOH/ethanol (1/1) solution. The novel wound dressing was prepared with fibers by paper-making method. We found the wound dressing can effective promote wound healing.3. The effects of N-succinyl chitosan with different molecular weight and low molecular weight chitosan on the proliferation of human periodontal ligament cells were systematically studied. N-succinyl chitosan can dramatically accelerate the growth of human periodontal ligament cells and increased with the increasing concentration while has no relation with molecular weight. Carboxymethyl chitosan quaternary ammonium salt was prepared and complex with Ca(OH)2 as pulp-cap. Animal experiment results indicated that carboxymethyl chitosan quaternary ammonium salt can strongly induce reparative dentine formation and showed a better ability in dentin inducing compared to calcium hydroxide.