Ryu J, Jeong Y I, Kim I S, Lee J H, Nah J W, Kim S H
College of Pharmacy, Chosun University, #375 Seosuk-Dong, Dong-Gu, 501-759, Kwangju, South Korea.
Int J Pharm. 2000 May 10;200(2):231-42. doi: 10.1016/s0378-5173(00)00392-6.
The triblock copolymer based on poly(epsilon-caprolactone) (PCL) as hydrophobic part and poly(ethylene glycol) (PEG) as hydrophilic one was synthesized and characterized. Core-shell type nanoparticles of poly(epsilon-caprolactone)/poly(ethylene glycol)/poly(epsilon-caprolactone) (CEC) block copolymer were prepared by a dialysis technique. According to the amphiphilic characters, CEC block copolymer can self-associate at certain concentration and their critical association concentration (CAC) was determined by fluorescence probe technique. CAC value of the CEC-2 block copolymer was evaluated as 0.0030 g/l. CAC values of CEC block copolymer decreased with the increase of PCL chain length, i.e. the shorter the PCL chain length, the higher the CAC values. From the observation of transmission electron microscopy (TEM), the morphologies of CEC-2 core-shell type nanoparticles were spherical shapes. Particle size of CEC-2 nanoparticles was 32.3+/-17.3 nm as a monomodal and narrow distribution. Particle size, drug loading, and drug release rate of CEC-2 nanoparticles were changed by the initial solvents and the molecular weight of CEC. The degradation behavior of CEC-2 nanoparticles was observed by 1H NMR spectroscopy. It was suggested that clonazepam (CNZ) release kinetics were dominantly governed by diffusion mechanism.
合成并表征了一种以聚（ε-己内酯）（PCL）为疏水部分、聚（乙二醇）（PEG）为亲水部分的三嵌段共聚物。通过透析技术制备了聚（ε-己内酯）/聚（乙二醇）/聚（ε-己内酯）（CEC）嵌段共聚物的核壳型纳米颗粒。根据两亲性特征，CEC嵌段共聚物在一定浓度下可自缔合，并通过荧光探针技术测定其临界缔合浓度（CAC）。CEC-2嵌段共聚物的CAC值评估为0.0030 g/l。CEC嵌段共聚物的CAC值随PCL链长的增加而降低，即PCL链长越短，CAC值越高。通过透射电子显微镜（TEM）观察，CEC-2核壳型纳米颗粒的形态为球形。CEC-2纳米颗粒的粒径为32.3±17.3 nm，呈单峰窄分布。CEC-2纳米颗粒的粒径、载药量和药物释放速率受初始溶剂和CEC分子量的影响。通过1H NMR光谱观察了CEC-2纳米颗粒的降解行为。结果表明，氯硝西泮（CNZ）的释放动力学主要受扩散机制控制。
