In Vitro Hydrolytic Degradation of Hydroxyl-Functionalized Poly(-hydroxy acid)s

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• 作者：Mark Leemhuis ; John A. W. Kruijtzer ; Cornelus F. van Nostrum ; Wim E. Hennink
• 刊名：Biomacromolecules
• 出版年：2007
• 出版时间：September 2007
• 年：2007
• 卷：8
• 期：9
• 页码：2943 - 2949
• 全文大小：114K
• 年卷期：v.8,no.9(September 2007)
• ISSN：1526-4602

文摘

The in vitro hydrolytic degradation of hydroxyl-functionalized poly(-hydroxy acid)s was investigated. Benzyl-ether-protected hydroxyl-functionalized dilactones (S)-3-benzyloxymethyl-(S)-6-methyl-1,4-dioxane-2,5-dione (1a)and (S)-3-benzyloxymethyl-1,4-dioxane-2,5-dione (1b) were copolymerized in a melt with various amounts ofL-lactide using benzyl alcohol and SnOct₂ as the initiator and catalyst, respectively. The benzyl groups wereremoved by hydrogenation to yield polyesters with hydroxyl functional groups, poly(lactic acid-co-hydroxymethylglycolic acid) and poly(lactic acid-co-glycolic acid-co-hydroxymethyl glycolic acid) (2a and 2b). Degradation ofthe hydroxyl-functionalized polyesters and poly(lactic-co-glycolic acid) (50/50) was studied by incubation ofpellets of these polymers in phosphate buffer (174 mM, pH 7.4) at 37 C. Polymer degradation was monitoredby mass-loss measurements and by gel permeation chromatography, differential scanning calorimetry, and ¹HNMR analysis. The degradation times ranging from less than 1 day (for the homopolymer of 2a) to 2 months(copolymer of 25% 2a and 75% lactide) were found. The degradation rates increased with increasing hydroxyldensity of the polymers, which was associated with a switch from bulk to surface erosion. NMR and thermalanalysis showed that the moieties with the hydroxyl groups were preferentially removed from the degradingpolymer. In conclusion, this study shows that the degradation rate of polyesters containing 2a and 2b can betailored from a few days to 2 months, making them very suitable for biomedical and pharmaceutical applications.