Preparation Of A CS/HPMC Thermosensitive Hydrogel And Study Of Its Properties

Due to the advantage of the simiar physical properties of hydrogel compare to natural tissue, it can be widely used in the biomedical field. In order to make the hydrogel to be an ideal biomaterial, the important thing is to select an ideal raw material Chitosan(Chitosan, CS) is a good polymer material with good biodegradability,antibacterial ability and biocompatibility. With the development of CS hydrogel, CS thermosensitive hydrogel has gradually coming into people’s view, which has become a hot research topic. Termosensitive hydrogel as a soft tissue engineering scaffold which can be used to treat a fixed site, avoid invasive surgery to attain minimally invasive purpose due to the properties of phase transition from sol to gel under a certain temperature. So the thermosensitive hydrogel can be widely used in the injection, stent materials.In this article, CS and hydroxypropyl methyl cellulose(HPMC) were used as raw materials to prepare a series of CS/HPMC solution by the "one-pot" method. In order to gain initially gel principle of the system, the research studied the lower critical solution temperature(LCST) of CS/HPMC solution by varying the next 3 factors: Percentage of CS content, Percentage of HPMC content and Percentage of Gel content. The physical and mechanical properties of the system were tested by SEM, FIRT, XRD and its biocompatibility and sustained effect were tested by MTT toxicity experiment and BSA drug delivery experiment(1) The article studied the effects of different factors on the CS/HPMC solution LCST with inversion method. The results showed that when the HPMC viscosity is constant, with the increase of CS content, the LCST of CS/HPMC system hardly changed, still at a high gel temperature, around 55 ℃; and at a certain CS content, and with the HPMC increased viscosity, the LCST of CS/HPMC system was graduallyraised, the highest LCST was about 60 ℃; at the same time when the CS content was constant, with the increase of HPMC content, the LCST of system gradually reduced,and when the CS, HPMC content were all constants, as the HPMC viscosity increased,the LCST of system gradually increased; when other factors are constant, the CS/HPMC system added glycerin(Gyl), finding the LCST of system had significantly lower, but different viscosity HPMC had some differences, at low viscosity segment, the system appeared similar nature, reduce the trend more obvious; the decreasing trend in viscosity, high viscosity HPMC was not very obvious. Rheometer also verified the above results, and thus presumably gel principle of the system: gel principle of the system was mainly due to the balance with hydrophilic and hydrophobicthe of the system. At low temperature HPMC, CS can form hydrogen bonds with water molecules to form a protective layer, when the temperature raised, the water molecules broken the shackles and hydration layer was damaged, the system exposed hydrophobic groups,including hydrogen bonding, hydrophobic association together, molecular chain entanglement.(2) Followed by orthogonal experimental design and the optimum preparation conditions of temperature-sensitive hydrogel was that CS content of 1%, HPMC content of 7%, glycerol content of 32%.(3) By SEM, FTIR, XRD tests for CS/HPMC/Gel system was characterized, the results showed that CS/HPMC system had a good pore structure, with the addition of glycerol the pores gradually disappeared, rendering the surface rough. And FIRT, XRD indicated that the system was a mechanical mixing and did not have any chemical reaction. Contact angle indirectly proofed gel principle of the system was indeed the balance of hydrophilic and hydrophobic, and texture tests showed that the system had certain gel strength.(4) Biocompatibility experiments reflected its usefulness as a biological material.The viscosity test of CS/HPMC/Gyl system indicated that the viscosity of the system hardly made changes with time, indicating that the system had good stability, long-term preservation. MTT cytoxicity assays showed that CS/HPMC/Gyl system toxicity rating below 0, which was non-toxic, and can promote the proliferation of cells. BSA drug release results showed that CS/HPMC/Gyl system had a sustained release of BSA, so CS/HPMC/Gyl system is rational injection spare temperature-sensitive material.