Synthesis And Characterization Of PH And Temperature Responsive Nanocomposite Hydrogels

Hydrogel is a kind of soft and wet solid material. Due to its unique properties, such as biocompatibility, non-toxic and biodegradability, it has been widely used in biomedical fields. Hydrogels hold tremendous promise especially in drug delivery system and tissue engineering. However, conventional hydrogels cannot be widely used by its poor mechanical properties. With the continuous development of nano technology and preparation process, the emergence of novel nanocomposite material has brought new hope for the development of hydrogel. The strength of the hydrogel as well as other excellent properties was greatly improved by the addition of nanoparticles. Based on the research background at home and abroad, we synthesized a pH and temperature responsive nanocomposite hydrogels in this thesis, and their in vitro controlled drug release behavior has been studied. Secondly, the effect of the different mass of nanoparticles in the hydrogel was also studied.In the first section, the hollow nanocapsule P（NIPAM-co-MAA） and nanocomposite hydrogel were prepared as the drug carrier to study the pH and temperature controlled drug release system. Firstly, with 3-（Trimethoxysilyl）propyl methacrylate（ MPS） modified nano silicon（ SiO₂@MPS） as template, we successfully grafted a temperature responsive N-isopropylacrylamide（NIPAM） and pH responsive methacrylic acid（MAA） polymer shell by precipitation polymerization process, and then we achieved a hollow nanocapsule by etching method. Doxorubicin hydrochloride（DOX·HCl） was used as drug model that was loaded in the hollow capsule, and part of the drug loaded microcapsules were embedded in the macro hydrogel. Finally, their drug release properties were studied respectively. The result shows that P（NIPAM-co-MAA） has a regular spherical structure and smooth surface, which can provides an adequate storage space for the drug. Meanwhile, drug loaded nanocomposite hydrogel has dramatically longer drug sustained release time than the drug carrier P（NIPAM-co-MAA）, as both of them has the pH and temperature responsive property, they can be used as an ideal drug carrier.In the second section, we purposed to study the effects of hydrogels which has embedded nanoparticles in it. For this end, nanocomposite hydrogels（FS） were prepared by the method of in situ free radical polymerization in the oxidation reduction initial system which containing different mass of SiO₂@MPS. Compared with traditional polymer hydrogel（OR gel）, FS gel has excellent mechanical properties. Observed by the scanning electron microscopy, we can come to the conclusion that SiO₂@MPS is not only a filler in the hydrogel network, but also act as a polymerization crosslinking agent, which increased the degree of crosslinking and then evenly distributed the external stress to improve the intensity. The study shows that light triggered FS gel has greater degree of crosslingking, which lead to high strength and high elasticity. However, the swelling rate of hydrogel decreased by the decrease of the diameter of hydrogel mesh.