Hydrogel Cartilage Repair Material Physical And Chemical Performance Research

The poly(vinyl alcohol)(PVA) hydrogels have been recognized as the potentialsubstitute materials for the artificial articular cartilage due to its higher water content,favorable mechanical and lubricating properties, and better biocompatibility. Theirscaffold can provide the microenvironment closer to the natural cartilage extracellularmatrix for cell proliferation and differentiation in the process of cartilage tissueregeneration. The study on the relationship among biocompatibility, application andphysical chemical properties is of significant to the development of tissue engineering.The system of tissue biomaterials is different from the system of classical physicalchemistry. To present the character of tissue material, the applicability of classicalphysical chemistry method should be explored. Therefore, it is of great importance tostudy the physical chemistry properties of PVA composite hydrogels used for repairingarticular cartilage defects.PVA composite hydrogels provide a proper model to study the properties of physicalchemistry of artificial articular cartilage. In this work, the properties of hydrogelscomposed of PVA/Dextran (chapter2), PVA/Chitosin (chapter3), PVA/PVP (chapter4)and PVA/Chitosan/Hydroxyapatite (chapter5) were studied. Hydrogels were preparedby a cooling and thawing method. We focus our attention on the properties of watercontent, degree of crystallinity, thermal dehydration, swelling kinetics, and mechanicalproperty. The relationship between these physical chemistry properties and the hydrogelcomposition, the technical parameters of preparation are analyzed.The kinetics of thermal dehydration shows that, the dehydration of hydrogel canbe thought as an evaporation process. By KAS and FWO methods, the activation energywere calculated, which decreases with the conversion increases. With the blend ofdextran and PVP into PVA, the activation energy and the water diffusion activationenergy were increased. For PVA/chitosin the activation energy is decreased but thewater diffusion activation energy is increased.The result of swelling kinetics shows that, the water content depends on thecooling and thawing cycle number, and increases with the amount of the crosslinkedcopolymers. For PVA/Dextran composite hydrogels, the swelling rate constant decreases with the amount of dextran, and for the hydrogels composite of othercomponent, CS, PVP and HA, the rate constant decrease first and then increase after itpass a minimum.The result of the degree of crystallinity shows that, the freezing and thawing cyclenumber leads the crystallinity increase. Dextran, chitosin and PVP reduce the meltingenthalpy of the dried PVA gel, and make the degree of crystallinity decreases. Thisphenomenon indicates that, the network structure of PVA was disordered by the blend ofdextran, chitosin, and PVP.After soaking in a simulated body fluid (SBF) at37°C for several days, apatitecrystal was observed on the surface of HA/CS/PVA hydrogel. This observationindicates that, the HA is favor of the link between hydrogel and bone.Mechanical tensile test shows that, as the cooling and thawing cycle number morethan3times, PVA composite hydrogels will have desirable tensile strength. By addinghydroxyapatite to the composite hydrogel, the mechanical properties, for example thecompressive strength, can be improved.