State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University , Shanghai 201620, China.
Biomacromolecules. 2013 Jun 10;14(6):1971-9. doi: 10.1021/bm4003464. Epub 2013 May 28.
Minimally invasive implants and/or scaffolds integrated with multiple functionalities are of interest in the clinical settings. In this paper, chitosan (CTS) functionalized poly(lactic-co-glycolic acid) (PLGA) microspheres containing a model payload, lysozyme (Lyz), were prepared by a water-in-oil-in-water emulsion method, from which cylindrical shaped rod (5 mm in diameter) was fabricated by sintering the composite microspheres in a mold. High-intensity focused ultrasound (HIFU) was then employed as a unique technique to enable shape memory and payload release effects of the three-dimensional (3-D) structure. It was found that incorporation of CTS into PLGA microspheres could regulate the transition temperature Ttrans of the microsphere from 45 to 50 °C and affect shape memory ratio of the fabricated cylindrical rod to some extent. Shape memory test and drug release assay proved that HIFU could modulate the shape recovery process and synchronize the release kinetics of the encapsulated Lyz in the rod in a switchable manner. Moreover, the two processes could be manipulated by varying the acoustic power and insonation duration. Mechanical tests of the microspheres-based rod before and after ultrasound irradiation revealed its compressive properties in the range of trabecular bone. Examination of the degradation behavior indicated that the introduction of CTS into the PLGA microspheres also alleviated acidic degradation characteristic of the PLGA-dominant cylindrical rod. With HIFU, this study thus demonstrated the desired capabilities of shape recovery and payload release effects integrated in one microspheres-based biodegradable cylindrical structure.
具有多种功能的微创植入物和/或支架在临床环境中受到关注。在本文中，通过水包油包水乳液法制备了壳聚糖（CTS）功能化的聚乳酸-共-羟基乙酸（PLGA）微球，其中包含模型载药物溶菌酶（Lyz），然后通过将复合微球在模具中烧结来制造圆柱形棒（直径 5 毫米）。然后，高强度聚焦超声（HIFU）被用作一种独特的技术，以使三维（3-D）结构具有形状记忆和载药释放效果。结果发现，将 CTS 掺入 PLGA 微球中可以调节微球的转变温度 Ttrans 从 45 到 50°C，并在一定程度上影响所制备的圆柱形棒的形状记忆比。形状记忆测试和药物释放试验证明，HIFU 可以以可切换的方式调节棒状包封的 Lyz 的形状恢复过程和释放动力学。此外，这两个过程可以通过改变声功率和照射时间来控制。微球基棒在超声辐射前后的机械测试表明，其在小梁骨范围内具有压缩性能。降解行为的检查表明，CTS 的引入也减轻了 PLGA 主导的圆柱形棒的酸性降解特性。通过 HIFU，这项研究因此展示了在一个基于微球的可生物降解的圆柱形结构中集成的形状恢复和载药释放效果的所需能力。
