title: Melting and swelling behaviors of UV-irradiated gelatin gel microcapsules.
abstract: Gelatin gel microcapsules with a narrow size distribution have been prepared for the use of regenerative therapy by means of SPG (Shirasu porous glass) emulsification and UV-induced cross linking, and the melting and swelling behaviors of the gel membrane of the microcapsules were observed. The gel melting temperature was proportional to the 2/3 power of UV irradiation time t for t<or=1 h and deviated from the 2/3 power behavior for t>or=1 h. The average cross-sectional area of the microcapsules that remains insoluble normalized by that at 25 degrees C monotonically increased with temperature for t<or=1 h. It then decreased, passed a minimum, and increased at high temperature for t>or=1 h. Repeated quenching of the gel microcapsules between two temperatures (25 and 40 degrees C) induced a reversible size change, which was attributed to the helix-coil transition of collagen molecules locally. From a theoretical consideration of gel particles, the observed gel melting behavior was explained well, and the scaled volume of the microcapsules was expressed as a function of scaled temperature with four fitting parameters for t<or=1 h.
authors.affiliation: Department of Physics, Faculty of Engineering, Gunma University, Kiryu, Gunma, 376-8515, Japan. yamamoto@phys.sci.gunma-u.ac.jp
authors.forename: Takao
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Michiru
authors.initials: M
authors.lastname: Koike
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Dobashi
mesh_terms: D002214:Capsules; D003094:Collagen / Q000737:chemistry*; D005780:Gelatin / Q000737:chemistry*; D006358:Hot Temperature; D008567:Membranes, Artificial; D017433:Protein Structure, Secondary / Q000528:radiation effects; D014466:Ultraviolet Rays
chemical_list: D002214:Capsules; D008567:Membranes, Artificial; D005780:Gelatin; D003094:Collagen