title: Physical stability and lyophilization of poly(epsilon-caprolactone)-b-poly(ethyleneglycol)-b-poly(epsilon-caprolactone) micelles.
abstract: The stability and lyophilization of core-shell PCL-PEG-PCL micelles were investigated by fluorescence spectra, DLS, DSC, WAXD, and FT-IR. The prepared micelles were not stable when they were stored in aqueous dispersion under different condition. Their size increased in the first 20 days and decreased gradually when the storage period was extended. Lyophilization experiment showed that the cryoprotective agent (glucose) was an essential additive to protect the micelles from aggregating during the lyophilization process. After lyophilizing and re-dispersion, the PCL-PEG-PCL micelles became larger in size compared to as-prepared ones. DSC, WAXD, and IR measurements indicated the hydrogen bonding was formed between the hydroxyl group in glucose and the carbonyl group in PCL-PEG-PCL micelles. The effect of added glucose on protection of micelles from aggregation can be explained by the formation of hydrogen bonding with PCL-PEG-PCL micelles and the formation of solid glucose matrix.
authors.affiliation: Laboratory of Mesoscopic Chemistry, Department of Polymer Science and Engineering, College of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, PR China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Hu
authors.forename: Yin
authors.initials: Y
authors.lastname: Ding
authors.forename: Yuan
authors.initials: Y
authors.lastname: Li
authors.forename: Xiqun
authors.initials: X
authors.lastname: Jiang
authors.forename: Changzheng
authors.initials: C
authors.lastname: Yang
authors.forename: Yonghua
authors.initials: Y
authors.lastname: Yang
mesh_terms: D003102:Colloids / Q000737:chemistry*; D004337:Drug Carriers / Q000737:chemistry*; D004355:Drug Stability; D005612:Freeze Drying; D005947:Glucose / Q000737:chemistry*; D008422:Materials Testing; D008823:Micelles; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D011091:Polyesters / Q000032:analysis / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000032:analysis / Q000737:chemistry*
chemical_list: D003102:Colloids; D004337:Drug Carriers; D008823:Micelles; D011091:Polyesters; C515340:poly(epsilon-caprolactone)-b-poly(ethyleneglycol)-b-poly(epsilon-caprolactone); D011092:Polyethylene Glycols; D005947:Glucose