Preparation of thermosensitive polymer nanoparticles by protein-mimetic cross-linking

Sachiko Kaihara, Masatoshi Narikawa, Keiji Fujimoto

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


Thermosensitive nanoparticles were prepared by mimicking protein folding where polymer aggregates were formed by precipitation of thermosensitive polymer chains followed by disulfide formation of their thiol groups. N-Isopropylacrylamide (NIPAM) and methacryloxy succini-mide (SuMA) were co-polymerized and then cysteamine was allowed to react with succinimide moieties of the polymer to render thiol moieties. A polymer aqueous solution precipitated to form nano-sized aggregates by increasing temperature above its lower critical solution temperature (LCST), and their sizes were monodispersed and tunable by the polymer concentration. The aggregates were cross-linked to produce nanoparticles by oxidation of thiol groups in a manner similar to formation of a disulfide bond of protein. As a result, the cross-linked nanoparticles exhibited swelling by decreasing temperature below the LCST of the copolymer. Fluorescein and bovine serum albumin (BSA) were chosen as a small and a large substance, respectively, and were encapsulated into the swollen nanoparticles at 25 °C. Fluorescein was rapidly released from both swollen and shrunken nanoparticles. Although BSA exhibited little release at any temperatures, it was released from nanopar-ticles by adding the reducing agent to dissociate the disul-fide cross-linking and incubating below the LCST.

Original languageEnglish
Pages (from-to)1317-1325
Number of pages9
JournalColloid and Polymer Science
Issue number13
Publication statusPublished - 2012 Aug


  • Disulfide cross-linking
  • Nanoparticles
  • Protein encapsulation

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Polymers and Plastics
  • Colloid and Surface Chemistry
  • Materials Chemistry


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