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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 22, Number 5
BKCSDE 22(5)
May 20, 2001 

Preparation of Core-shell Type Nanoparticles of Poly(ε-caprolactone) /Poly(ethylene glycol)/Poly( ε-caprolactone) Triblock Copolymers
Jae-Gon Ryu, Young-Il Jeong, Young-Hoon Kim, In-Sook Kim, Do-Hoon Kim, Sung-Ho Kim
Triblock copolymer, Core-shell type nanoparticles, Biodegradation.
A triblock copolymer based on poly(ε-caprolactone) (PCL) as the hydrophobic part and poly(ethylene glycol) (PEG) as the hydrophilic portion was synthesized by a ring-opening mechanism of ε-caprolactone with PEG containing a hydroxyl group at both ends as an initiator. The synthesized block copolymers of PCL/PEG/PCL (CEC) were confirmed and characterized using various analysis equipment such as 1H NMR, DSC, FT-IR, and WAXD. Core-shell type nanoparticles of CEC triblock copolymers were prepared using a dialysis technique to estimate their potential as a colloidal drug carrier using a hydrophobic drug. From the results of particle size analysis and transmission electron microscopy, the particle size of CEC core-shell type nanoparticles was determined to be about 20-60 nm with a spherical shape. Since CEC block copolymer nanoparticles have a core-shell type micellar structure and small particle size similar to polymeric micelles, CEC block copolymer can self-associate at certain concentrations and the critical association concentration (CAC) was able to be determined by fluorescence probe techniques. The CAC values of the CEC block copolymers were dependent on the PCL block length. In addition, drug loading contents were dependent on the PCL block length: the larger the PCL block length, the higher the drug loading content. Drug release from CEC core-shell type nanoparticles showed an initial burst release for the first 12 hrs followed by pseudo-zero order release kinetics for 2 or 3 days. CEC-2 block copolymer core-shell type nanoparticles were degraded very slowly, suggesting that the drug release kinetics were governed by a diffusion mechanism rather than a degradation mechanism irrelevant to the CEC block copolymer composition.
467 - 475
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