Dansyl Fluorescence and Local Structure of Dansyl-Labeled Core-Shell and Core-Hair Type Microspheres in Solution
✍ Scribed by Kazuyuki Horie; Sadakazu Yamada; Shinjiro Machida; Satoshi Takahashi; Yoko Isono; Haruma Kawaguchi
- Publisher
- John Wiley and Sons
- Year
- 2003
- Tongue
- English
- Weight
- 298 KB
- Volume
- 204
- Category
- Article
- ISSN
- 1022-1352
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✦ Synopsis
Abstract
Core‐shell type microspheres with fluorescent dansyl groups at random sites in crosslinked poly(N‐isopropylacrylamide) (PNIPAM) shell chains and core‐hair type microspheres with dansyl groups at terminal sites of PNIPAM hair chains graft‐polymerized with living‐radical mechanism were prepared. Fluorescent spectra indicating the microenvironments of dansyl groups attached to the microspheres and their dependences on temperature and solvent compositions were compared to those of dansyl groups in PNIPAM bulk gels and in free solutions. Fluorescence peak wavelength of dansyl groups in the core‐shell type microspheres showed an extraordinary blue shift in water, suggesting that dansyl groups are incorporated in the semi‐interpenetrating polymer network (SIPN) region of the core‐shell boundary. This is supported by a confocal laser‐scanning fluorescence microscope (CLFM) image of a single particle for the core‐shell type microsphere. Dansyl groups at the chain ends of PNIPAN hairs of the core‐hair type microspheres in water are also located on the surface of hydrophobic cores.
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