The Critical Micelle Concentration for the Solution of PLGA/PEG Tri-block Copolymers

Various controlled drug delivery systems have been investigated for their potential in treatment of chronic diseases. Among them, triblock copolymers of PLGA (poly-d,l-lactic-co-glycolic acid) (A-block) and PEG (poly ethylene glycol) (B-block) are the most popular.The synthesis and characterization of thermosensitive PLGA-PEG-PLGA triblock copolymers as in situ gelling matrices were investigated in this paper. The phase transition temperature and the critical micelle concentration (CMC) of copolymer solutions was determined by differential scanning calorimetry (DSC) and spectrophotometry, respectively. The size of micelles was determined with laser light scattering method. Solutions of 20 and 25% (w/v) copolymers with LA/GA ratios of 5/1 seemed to be the most ideal in situ gelling matrices for drug delivery systems according to the sol-gel transition temperatures. The CMC of PLGA-PEG1500-PLGA with LA/GA: 5/1 was found about 0.017 (wt %). Such a low CMC confirms the stability of micelles against possible dilution of drug delivery system in body. It was also found that the copolymer structure and concentration played critical roles in controlling the sol-gel transition temperature, the CMC and the size of the nano micelles in the copolymer solutions

کلیدواژه ها:

In situ gel ، Thermosensitive ، PLGA ، PEG ، CMC