Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, South Korea.
Department of Radiology, College of Medicine, Yonsei University, Seoul, 03722, South Korea.
Small. 2017 Aug;13(29). doi: 10.1002/smll.201700646. Epub 2017 May 30.
Biodegradable microcapsules with a large aqueous lumen and ultrathin membrane are microfluidically designed for sustained release of hydrophilic bioactives using water-in-oil-in-water double-emulsion drops as a template. As a shell phase, an organic solution of poly(lactic-co-glycolic acid) is used, which is consolidated to form a biodegradable membrane. The encapsulants stored in the lumen are released over a long period of time as the membranes degrade. The period can be controlled in a range of -three to five months at neutral pH condition by adjusting membrane thickness, providing highly sustained release and potentially enabling the programed release of multiple drugs. At acidic or basic condition, the degradation is accelerated, leading to the release in the period of approximately two months. As the membrane is semipermeable, the microcapsules respond to the osmotic pressure difference across the membrane. The microcapsules are inflated in hypotonic condition and deflated in hypertonic condition. Both conditions cause cracks on the membrane, resulting in the fast release of encapsulants in a day. The microcapsules implanted in mice also show sustained release, despite the period is decreased to a month. It is believed that the microcapsules are promising for the in vivo sustained release of drugs for high and long-term efficacy.
具有大水性内腔和超薄膜的可生物降解微胶囊是通过使用油包水双乳液滴作为模板来设计的，用于亲水性生物活性物质的持续释放。作为壳相，使用聚（乳酸-共-乙醇酸）的有机溶液，将其固结以形成可生物降解的膜。随着膜的降解，内腔中储存的包封剂会在很长一段时间内释放出来。通过调整膜的厚度，可以将释放时间控制在中性 pH 条件下的三到五个月范围内，从而实现高度持续的释放，并有可能实现多种药物的程序释放。在酸性或碱性条件下，降解会加速，导致在大约两个月的时间内释放。由于膜是半透性的，微胶囊会对膜两侧的渗透压差做出响应。在低渗条件下微胶囊会膨胀，在高渗条件下会瘪缩。这两种情况都会导致膜破裂，从而导致包封剂在一天内快速释放。植入小鼠体内的微胶囊也表现出持续释放，尽管释放时间缩短至一个月。人们相信，这些微胶囊有望用于体内高疗效和长效药物的持续释放。
