TEMPERATURE - CONTROLLED PH - DEPENDENT FORMATION OF IONIC GELS BASED ON CHITOSAN OR DERIVATIVES THEREOF

摘要

The present invention relates to a temperature-controlled pH-dependant formation of ionic polysaccharide gels, such as chitosan/organo-phosphate aqueous systems, and methods of preparation thereof. While chitosan aqueous solutions are pH-dependant gelating systems, the addition of a mono-phosphate dibasic salt of polyol or sugar to chitosan aqueous solutions leads to further temperature-controlled pH-dependant gelation. Solid organo-phosphate salts (1-20 % w/v) are added and dissolved at low temperature (10 °C) within 0.5 to 4.0 % w/v chitosan in aqueous acidic solutions. Aqueous chitosan/organo-phosphate solutions are initially stored at low temperatures (4 °C), then endothermally gelated within the temperature range of 30 to 60 °C. Chitosan/organo-phosphate solutions rapidly turn into gels at the desired gelation temperature. Gelation can be ex vivo within any receivers or molds, or in situ in animals or humans (in vivo) so as to fill a tissue defect or cavity.