Engwicht A, Girreser U, Müller B W
Department of Pharmaceutics and Biopharmaceutics, Christian Albrecht University, Gutenbergstrasse 76, 24105, Kiel, Germany.
Int J Pharm. 1999 Aug 5;185(1):61-72. doi: 10.1016/s0378-5173(99)00127-1.
The Aerosol Solvent Extraction System (ASES) process uses supercritical carbon dioxide for the production of microparticles. Since the critical temperature for this gas is at 304 K, polymers that are used in this process must fulfil certain requirements in crystallinity, and thermal behavior. This can be achieved by the use of blocked copolymers and thus the presence of semicrystalline microdomains in the polymers. However, changing the sequences of the comonomers dilactide and lactide often leads to polymers of low solubility due to long glycolide blocks. In this study, the critical properties of two blocked co-polymers were investigated, such as the blocked structure itself by (1)H-NMR and (13)C-NMR, the thermal behavior by differential scanning calorimetry (DSC), and the crystallinity by powder diffraction. The impact of these properties on microparticles formed by those polymers was also object of these studies. Additionally, two different model drugs, albumin and estriolm were embedded to investigate the impact of different polymer properties on drug content and release.
气溶胶溶剂萃取系统（ASES）工艺使用超临界二氧化碳来生产微粒。由于这种气体的临界温度为304K，该工艺中使用的聚合物必须在结晶度和热行为方面满足一定要求。这可以通过使用嵌段共聚物来实现，从而使聚合物中存在半结晶微区。然而，改变共聚单体丙交酯和乙交酯的序列通常会由于长的乙交酯嵌段而导致聚合物溶解度较低。在本研究中，研究了两种嵌段共聚物的临界性质，例如通过（1）H-NMR和（13）C-NMR研究嵌段结构本身，通过差示扫描量热法（DSC）研究热行为，以及通过粉末衍射研究结晶度。这些性质对由这些聚合物形成的微粒的影响也是这些研究的对象。此外，还包埋了两种不同的模型药物白蛋白和雌三醇，以研究不同聚合物性质对药物含量和释放的影响。
