Structural characteristics of mPEG-PDLLA and their effects on micelle stability
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The correlation between polymer microstructure of mPEG-PDLLA and secondary aggregation of its micelle was studied. Close examination of 1H NMR spectra revealed that the methine moieties, -CH(CH3)-, of mPEG-PDLLA polymer well represented its microstructure. To elucidate the physicochemical characteristics of various microstructures, we have developed an index, called L-ratio, to indicate the relative content of heterotactic component within the polymer. Storage stability of micelles from six polymers with different L-ratios (L-ratio ranging from 28 to 33%) was studied at 30 °C and 50 °C, and changes in average particle size were monitored to evaluate their secondary aggregation. We have found that polymers with high L-ratio takes longer time to secondary aggregation of polymeric micelles to occur. The findings should provide insightful guidance in the development of polymeric micelles.
KeywordsPolymeric micelle Block copolymer mPEG-PDLLA Polymer microstructure Stability Secondary aggregation
The authors thank Dr. Joonyoung Park for his discussion and proofreading during revision of the manuscript.
This study was supported by R&D fund of Samyang Biopharmaceutical Corporation and Grant 10047811 from Ministry of Trade, Industry and Energy (MOTIE, South Korea).
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Conflict of interest
The authors declare that they have no conflict of interest.
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