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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 23, Number 6
BKCSDE 23(6)
June 20, 2002 

Preparation and Reconstitution of Core-shell Type Nanoparticles of Poly(ε-caprolactone)/Poly(ethyleneglycol)/Poly(ε-caprolactone) Triblock Copolymers
Younh-Jl Jeong, Jae-Gon Ryu, Young-Hoon Kim, Sung-Ho Kim
Triblock copolymer, Core-shell type nanoparticles, Cytotoxicity.
One of the important characteristic of core-shell type nanoparticles in the long-term storage and reuse as an aqueous injection solution when required. For this reason, reconstruction of lyophilized core-shell type nanoparticles is considered to be essential. BAB type triblock copolymers differ from AB type diblock copolymers, when contain the A block as hydrophilic part and the B block as a hydrophobic part, by not being easily redistributed into phosphate-buffered saline (PBS, pH 7.4, 0.1M). Therefore, lyophilized core-shel type nanoparticles of CEC triblock copolymer were reconstituted using a sonication process with a bar-type sonicator in combination with a freezing-thawing process. Soncation for 30s only resuspended CEC nanoparticles in PBS; their particle size distribution showed a bimodal pattern, with a small fraction of aggregates, while the dialysis of aqueous nanoparticles solution showed a monomodal pattern with narrow size distribution. The bimodal size distribution pattern and the aggregates were reduced by further sonication for 120s but these nanoparticles showed a wide size distribution. The initial burst of drug releasse was increased by reconstitution process. The reconstitution of CEC core-shell type nanoparticles by freezing-thawing resulted in trimodal distribution pattern and formed aggregates, although freezing-thawing process was easier than sonication. Drug release from CEC nanoparticles prepared by freezing-thawing was slower than from the original dialysis solution. Although core-shell type nanoparticles of CEC triblock copolymers were not easily redistributed into aqueous solution, reconstruction of CEC core-shell type nanoparticles was successively performed. Cytotoxicity testing of core-sell type nanopraticles of CEC-2 triblock copolymers containing clonazepam (CNZ) was performed using L929 cells. Cytotoxicity of CNZ was decreased by incorpration into nanoparticles.
872 - 878
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