Cited by 273Advanced Polymer Synthesis and CharacterizationHydrogels: synthesis, properties, applicationsNanoparticle-Based Drug Delivery

Preparation and characterization of thermally responsive block copolymer micelles comprising poly(N-isopropylacrylamide-b-DL-lactide)

Kohori, Fukashi, Sakai, Kiyotaka, Aoyagi, Takao, Yokoyama, Masayuki, Sakurai, Yasuhisa, Okano, Teruo·1998·Journal of Controlled Release

Abstract

The thermally sensitive block copolymer, poly(N-isopropylacrylamide-b-dl-lactide) (PIPAAm-PLA), was synthesized by ring-opening polymerization of dl-lactide initiated from hydroxy-terminated poly (N-isopropylacrylamide) (PIPAAm). A PIPAAm bearing a single terminal hydroxyl group was prepared by telomerization using 2-hydroxyethanethiol as a chain-transfer agent. Successful preparation of PIPAAm and the PIPAAm-PLA block copolymer was verified by gel permeation chromatography (GPC) and 1H-NMR spectroscopy. Polymeric micelles were prepared from block copolymers using a dialysis method. Their solutions showed reversible changes in optical properties: transparent below a lower critical solution temperature (LCST) and opaque above the LCST. Dynamic light scattering measurements were used to observe the formation of micellar structures approximately 40 nm in diameter, which do not change between 20 degreesC and 30 degreesC. Above the LCST, polymer micelles aggregated, a phenomenon found to be reversible since the aggregates dissociated again by cooling below the LCST. Further observations using atomic force microscopy (AFM) confirmed this behaviour. The properties of this block copolymer system are interesting from both applied and fundamental perspectives, particularly for active targeting as drug carriers.

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Crossref · 10.1016/s0168-3659(98)00023-6

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Authors
Kohori, F., Sakai, K., Aoyagi, T., Yokoyama, M., Sakurai, Y., & Okano, T.
Affiliations
  • Waseda University (JP)
  • Tokyo Women's Medical University (JP)
Corresponding author
Okano, Teruo
Venue
Journal of Controlled Release
Publisher
Elsevier BV
Published
1998-10
Volume
55
Issue
1
Pages
87-98
ISSN
0168-3659 (ISSN-L)
OpenAlex
W2031773818
Cited by
273
References
26
Citations by year
2026: 1 · 2025: 3 · 2024: 2 · 2023: 1 · 2022: 7 · 2021: 6 · 2020: 4 · 2019: 6 · 2018: 5 · 2017: 12 · 2016: 4 · 2015: 7 · 2014: 12 · 2013: 12 · 2012: 12
FWCI
6.05
Type
journal article
Language
en
Open access
closed
Locations
  • Journal of Controlled Release (publishedVersion)
  • PubMed (publishedVersion)
Funders
Ministry of Education, Culture, Sports, Science and Technology (08672569)
Topics
  • Physical Sciences › Chemistry › Organic Chemistry › Advanced Polymer Synthesis and Characterization
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Medicine › Hydrogels: synthesis, properties, applications
  • Physical Sciences › Materials Science › Biomaterials › Nanoparticle-Based Drug Delivery
Keywords
poly(N-isopropylacrylamide), poly(D,L-lactide), block copolymer micelles, lower critical solution temperature, micellar aggregation, drug carriers, active targeting, ring-opening polymerization, telomerization
MeSH terms
Acrylamides, Chromatography, Gel, Light, Micelles, Magnetic Resonance Spectroscopy, Scattering, Radiation, Spectrometry, Fluorescence, Temperature, Microscopy, Atomic Force

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