Synthesis and characterization of photocrosslinked poly(D,L-lactic acid-ethylene glycol-D,L-lactic acid) diacrylate nanogel

• Main Author: 張雅棻
• Other Authors: I-Ming Chu
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/04002660546563650333

碩士 === 國立清華大學 === 化學工程學系 === 94 === In this study, ABA type amphiphilic triblock copolymers consisting of poly(ethylene glycol) (PEG) (A) as hydrophilic segment and poly(D,L-lactic acid) (PLA) (B) as hydrophobic block were synthesized by ring opening polymerization. These copolymers could form micelles by solvent evaporation method due to their characteristic of self-assembling. These micelles entrapped the hydrophobic drug, Camptothecin (CPT), in their hydrophobic core. Though the size of the micelles was less than 200 nm, the instability restricted the application. Besides, the encapsulation of CPT was only 0.01 mg based on 20 mg micelles, and more than 80 % of the drug released in 1 day. In order to improve these disadvantages of micelles, the nanogels prepared by UV irradiation with PEL diacrylate was developed as a new drug carrier. The diameter of nanogels was easily controlled in a range of 140 ~201 nm by manipulating the concentration of crosslinkers, ethylene glycol dimethacrylate (EGDMA) and trimethylolpropane trimethacrylate (TMPTMA). In the EGDMA system, the increase of EGDMA, size revealed the nanogels swelled less. However, the TMPTMA system showed the different circumstance due to the different structure of these two crosslinkers. All these nanogels exhibited good stability without aggregation in 30 days. CPT encapsulated in these nanogels by two methods: loaded as micelles prepared before radiation and loaded by diffusing CPT into the crosslinked core of nanogels. The encapsulated CPT was amount of 0.1 ~ 0.9 mg based on 20 mg nanogels depended on the encapsulation methods. But these nanogels released CPT in a gradual mechanism and exhibited good stability. As results, these nanogels are very potential in drug controlled release system.