Fabrication of monodisperse gel shells and functional microgels in microfluidic devices
Fabrication of monodisperse gel shells and functional microgels in microfluidic devices
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DOI：
10.1002/anie.200604206
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发表时间：
2007-01-01
影响因子：
16.6
通讯作者：
Weitz, David A.
中科院分区：
文献类型：
--
作者：
Kim, Jin-Woong;Utada, Andrew S.;Weitz, David A.
微凝胶是由化学交联的三维聚合物网络组成的胶体凝胶颗粒;这些网络能够通过响应外部刺激排出或吸收大量水而急剧收缩或膨胀。[1，2]例如，通过改变介质的pH值，温度或离子强度，或通过施加电场或磁场，可以实现尺寸的大变化;正是这种响应使得微凝胶在药物递送，[3，4]生物传感，[5]诊断，[6，7]生物分离，[8]和光学设备中的应用是理想的。[9，10]为了进一步扩大它们的适用范围，已经努力产生已经与预形成的官能化材料复合的微凝胶，所述预形成的官能化材料赋予微凝胶额外的期望性质。[11-14]这些预制材料的范围从分子到微粒，并且通常通过特定的相互作用与凝胶基质复合。与原始交联聚合物网络相比，所得复合微凝胶通常显示出对外部刺激的物理响应急剧下降;[15-17]这是不期望的副作用，因为给定应用的微凝胶性能是基于其对外部刺激的敏感性。除了功能性之外，微凝胶群体的尺寸分布也很重要;提供均匀分布的微凝胶应用制剂[18]以及控制胶囊或吸附剂的释放动力学是至关重要的。[19]从性能和适用性的角度来看，有必要的方法，以产生单分散微凝胶，保持高灵敏度的外部刺激，而不管被纳入补充functions.Here的材料，我们描述了一个灵活和简单的方法，用于产生单分散悬浮液的新的微凝胶基材料使用毛细管微流控技术。[20]这种技术使我们能够生成并精确控制基于微凝胶的颗粒的尺寸[21-23]，而不会牺牲所得微凝胶的物理响应。我们产生了两种新的微凝胶结构：球形微凝胶壳和球形微凝胶颗粒，它们在与预先形成的胶体颗粒物理复合后保持对外部刺激的完全敏感性。微凝胶壳的总体尺寸和厚度可以随温度调节。我们在一个步骤中生成了球形微凝胶颗粒，这使我们能够自由地将功能材料掺入聚合物网络中。我们使用量子点，磁性纳米颗粒和聚合物微粒作为可以添加以向原始微凝胶提供特定化学，物理或机械特性的材料的示例。
Microgels are colloidal gel particles that consist of chemically cross-linked three-dimensional polymer networks; these networks are able to dramatically shrink or swell by expelling or absorbing large amounts of water in response to external stimuli.[1, 2] The large change in size can be achieved, for example, by modifying the pH, temperature, or ionic strength of the medium, or by applying electric or magnetic fields; it is this response that makes microgels desirable for applications in drug delivery,[3, 4] biosensing,[5] diagnostics,[6, 7] bioseparations,[8] and optical devices.[9, 10] To further expand their range of applicability, there have been efforts to generate microgels that have been complexed with preformed functionalized materials that impart additional desirable properties to the microgel.[11–14] These preformed materials range from molecules to microparticles and are typically complexed with the gel matrix through specific interactions. The resulting complexed microgels usually show a drastic decrease in their physical response to external stimuli compared to that of the original cross-linked polymer networks;[15–17] this is an undesirable side effect since the microgel performance for a given application is based on its sensitivity to external stimuli. In addition to functionality, the size distribution of a population of microgels is important; it is critical to provide a homogeneous distribution of microgels applying formulations [18] and in controlling the release kinetics of encapsulates or adsorbents.[19] From the standpoint of performance and applicability, there is a need for methods to generate monodisperse microgels that maintain high sensitivity to external stimuli irrespective of the materials that are incorporated to add complementary functions.Here, we describe a flexible and straightforward method for generating monodisperse suspensions of new microgelbased materials using a capillary microfluidic technique.[20] This technique enabled us to generate and precisely control the size of the microgel-based particles [21–23] without sacrificing the physical response of the resulting microgels. We generated two novel microgel structures: a spherical microgel shell and spherical microgel particles that retain their full sensitivity to external stimuli after being physically complexed with preformed colloidal particles. The overall size and thickness of the microgel shells can be tuned with temperature. We generated the spherical microgel particles in a single step, which allows us to freely incorporate functional materials into the polymer network. We used quantum dots, magnetic nanoparticles, and polymer microparticles as examples of the materials that can be added to provide specific chemical, physical, or mechanical properties to the original microgels.