Preparation And Research Of The PH And Thermosensitive Hydrogels In Drug Carrier

At present,the hydrogels is a kind of drug carrier which has been widely researched.According to the hydrogels whether can response the external stimulus or not,it can be divided into traditional hydrogles and smart hydrogels.Now,the smart hydrogels are mainly divided into several categories,such as pH-sensitive,therom-sensitive,photo-sensitive,pressuresensitive,magnetic-sensitive and so on.The intelligent hydrogels can rapidly respond to changes in the external environment,and cause the phase transiton.Therefore,the intelligent hydrogels have great application prospects in biomedical,especially in the aspect of controlled release of the drug.In this paper,the pH and thermo-sensitive hydrogel drug carrier was prepared through the semi-interpenetrating network(Semi-IPN)technology by using the N-isopropyl acrylamide(NIPAAm)as temperature sensitive components and methacrylic acid(MAA)as pH sensitive components and discuss their drug loading and release properties.Chapter 1: summarize the the present situation of the pharmaceutical field,the properties,classification and preparation methods of gel;the stateof-the-art of pH-sensitive hydrogel and thermo-sensitive hydrogel and their application in drug carrier was introduced.Chapter 2: In order to determine the preliminaryexperimental schemes,the orthogonal experiment of four factors and three levels was desigened.The PMAA hydrogels was prepared by the polymerization of methacrylic acid.Using the acrylic acid alkyl ester as raw materials modified the PMAA hydrogles,in order to adjust the pH response range and then a pH sensitive hydrogels were prepared.The surface morphology,swelling properties,p H response and reversible swellingwere characterized.The results showed that the abrupt change pHof PMVA-C5 hydrogel was about 7.4,the swelling rate was up to 72 %,and they have showed excellent swelling-deswelling reversibility and repeat-ability in pH 1.5 and 7.2.Chapter 3: refer to the cheme of synthesis of pH sensitive hydrogel,the pH and thermo-sensitive hydrogels is obtained by semi-interpenetrating network based on N-isopropyl acrylamide(NIPAAm)and copolymer of methyl propionic acid and propionic acid isooctyl ester,and then the swelling properties,lower critical solution temperature(LCST)and morphology of them were characterized.The results showed that the LCST of hydrogel MPN31 is 37.3 ℃,which is close to the human body temperature so that can be used as drug carrier.Chapter 4: the drug loading and release properties of MN31 hydrogel in simulated intestinal fluid(SIF)and simulatedgastric juice(SGJ)were studied by using bovine serum albumin(BSA)as the model drug,and he drug loading and the cumulative release rate were calibrated.The results show that the loading of BSA in MPN31 was 6.844 mg/g;he accumulative release rate of BSA in different temperature and pH have presented differences,even up to 65 %.Hydrogel MPN31 has showed excellent p H and temperature sensitivity,so it is promised to become drug carrier.