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Fluorescence analysis for thermo‐sensitive hydrogel microspheres
Author(s) -
Fujimoto K.,
Nakajima Y.,
Kashiwabara M.,
Kawaguchi H.
Publication year - 1993
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.4990300217
Subject(s) - lower critical solution temperature , poly(n isopropylacrylamide) , fluorescence , materials science , chemical engineering , polymer , self healing hydrogels , contact angle , adsorption , polymer chemistry , polymerization , precipitation polymerization , quenching (fluorescence) , thermoresponsive polymers in chromatography , radical polymerization , chemistry , chromatography , copolymer , composite material , organic chemistry , high performance liquid chromatography , optics , physics , reversed phase chromatography , engineering
Abstract Poly( N ‐isopropylacrylamide) (PNIPAM) hydrogel microspheres were prepared by precipitation polymerization above the polymer's lower critical solution temperature (LCST) in water. The hydrodynamic size of PNIPAM microspheres exhibited a thermo‐sensitive change around the LCST. In order to obtain information about the interface of the hydrogels, contact angle measurement, protein adsorption, and fluorescence analysis were performed. Contact angle measurement and protein adsorption showed a gradual change around the LCST similar to the change of the hydrodynamic size. However, fluorescence study exhibited a sharp change at the LCST. In addition, a quenching experiment was employed to elucidate the location of the fluorescent probes. In the PNIPAM latex, the probes were located where they were less quenchable as compared to the PNIPAM solution. It seems probable that the probes can penetrate into the crosslinked PNIPAM hydrogel and might reflect the inner environment of the hydrogel. The effect of salt on thermo‐sensitive behaviour was also detected by fluorescence analysis. On the other hand, the hydrogel microsphere prepared from poly(acryloyl pyrrolidine) (PAPr) showed a gradual change in fluorescence with temperature.