Preparation Of Chitosan/acrylic Acid Composite Hydrogels For Controlled Drug Delivery

The hydrogel is a kind of hydrophilic polymer materials with good biocompatibility, which undergo significant changes of volume or shape in response to a variety of environmental stimuli, such as temperature, p H, electrical fields, etc. In the past few years, considerable researches have focused on stimclus-responsive hydrogels due to their various applications in artificial organ, enzyme, tissue engineering, controlled drug release, biosensor, on-off switches, and so on.Chapter one: IntroductionThe classification, preparation methods, and the applications in various fields of hydrogels were reviewed brifly in this part. In addition, the development prospect of this kind of new materials was discussed, and the research idea of this paper was put forward.Chapter Two: Chitosan and polyacrylic acid composite hydrogel drug controlled release behavior researchThe chitosan and acrylic acid were used to prepare the composite hydrogel(CS-PAA) by using radical polymerization method. The influences of reaction temperature, neutralization degree of acrylic acid, amounts of cross-linking agent and acrylic acid on the swelling degree of the composite hydrogels were investigated in detail. In addition, the controlled release behaviors of the prepared hydrogels for niacin were also evaluated. The results showed that the swelling degree of the prepared hydrogels was high as 1228g/g and it exhibited excellent p H and ionic strength sensitivity. The cumulative release rate in buffer solution with p H=6.86 is obviously more than which in p H=1.8. Therefore, the hydrogels can be used as carriers of intestinal oral drugs.Chapter Three: Preparation of chitosan/poly(ethylene glycol)/poly(acrylic acid)composite hydrogels for controlled drug deliveryA composite hydrogel CS/PEG/PAA was prepared via free radical polymerizationof CS, PEG and AA in the presence of initiator and cross-linking agent.four drugs with different structure and property(niacin, niacinamide, isoniazide and5-fluorouracil) were chosen as the model drugs to evaluate the controlled drug delivery behaviors of the hydrogel. The results indicated that the cumulative drug release amount(R) and release rate of niacinamide and isoniazide in medium with p H=1.80 were higher than which in p H=6.86. But both the cumulative drug release amount and release rate were higher in p H=6.86 solution for niacin. However, there is no significant difference for 5-fluorouracil in the two media. So the prepared hydrogel maybe can be used as a targeted drug released carrier.Chapter Four: Preparation and characterization of CS/β-CD/PAA hydrogels for controlled drug deliveryA novel macroporous composite hydrogels were synthesized by free radical polymerization of crylic acid(AA), chitosan(CS) and beta-cyclodextrin(β-CD) with N,N-methylenebisacrylamide(MBA) as the cross-linking agent. The swelling properties were investigated in detail. The results revealed that the prepared hydrogels exhibited high p H sensitivity and well reversible property by undergoing a number of swelling/de-swelling recycles. Nicotinamide was chosen as a model drug, We changed the β-CD quantity to study the drug controlled release. The results indicated that the release rate decreased with the increasing of β-CD content in acidic solution(p H=1.80).