Microfluidic Generation of Droplets with a High Loading of Nanoparticles
Microfluidic Generation of Droplets with a High Loading of Nanoparticles
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DOI：
10.1021/la3025952
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发表时间：
2012-09-18
期刊：
影响因子：
3.9
通讯作者：
Stone, Howard A.
中科院分区：
文献类型：
--
作者：
Wan, Jiandi;Shi, Lei;Stone, Howard A.
用于控制胶体簇生成的微流体方法，例如通过将胶体颗粒封装在液滴中，已用于合成包括药物递送载体在内的功能材料。然而，大多数研究使用低浓度的原始胶体悬浮液（60 wt%）颗粒浓度。研究了三种类型的微流体装置：PDMS 流聚焦装置、PDMS T 型连接装置和微毛细管装置，用于将高浓度聚苯乙烯 (PS) 纳米颗粒直接封装在液滴中。特别是，研究表明，通过软光刻制造的 PDMS 装置可以从 25 wt% PS 悬浮液中产生液滴，而由玻璃毛细管制成的微毛细管装置能够从 67 wt% 96 PS 纳米粒子悬浮液中产生液滴。当 PS 浓度在 0.6 至 25 wt 96 之间时，发现液滴的尺寸随着油水流量比的变化而变化，并且与初始悬浮液中颗粒的浓度无关。使用任一 PDMS 装置，分别使用 20 至 1 的流量比 Q（油）/Q（水）来制备大约 12 至 40 μm 的液滴尺寸。然而，由于 PS 胶体与 PDMS 装置表面之间的相互作用，在高 PS 浓度 (>25 wt%) 下，PDMS 装置会发生堵塞。另一方面，玻璃微毛细管装置不易堵塞，即使 PS 纳米粒子的浓度达到 67 wt%，也能连续产生液滴。我们相信，我们的研究结果表明了控制生成充满高负载纳米颗粒的乳液的有用方法和指南，这对于药物输送应用非常有用。
Microfluidic approaches for controlled generation of colloidal clusters, for example, via encapsulation of colloidal particles in droplets, have been used for the synthesis of functional materials including drug delivery carriers. Most of the studies, however, use a low concentration of an original colloidal suspension (60 wt %) particle concentrations. Three types of microfluidic devices, PDMS flow-focusing, PDMS T-junction, and microcapillary devices, are investigated for direct encapsulation of a high concentration of polystyrene (PS) nanoparticles in droplets. In particular, it is shown that PDMS devices fabricated by soft lithography can generate droplets from a 25 wt % PS suspension, whereas microcapillary devices made from glass capillary tubes are able to produce droplets from a 67 wt 96 PS nanoparticle suspension. When the PS concentration is between 0.6 and 25 wt 96, the size of the droplets is found to change with the oil-to-water flow rate ratio and is independent of the concentration of particles in the initial suspensions. Drop sizes from similar to 12 to 40 mu m are made using flow rate ratios Q(oil)/Q(water) from 20 to 1, respectively, with either of the PDMS devices. However, clogging occurs in PDMS devices at high PS concentrations (>25 wt %) arising from interactions between the PS colloids and the surface of PDMS devices. Glass microcapillary devices, on the other hand, are resistant to clogging and can produce droplets continuously even when the concentration of PS nanoparticles reaches 67 wt %. We believe that our findings indicate useful approaches and guidelines for the controlled generation of emulsions filled with a high loading of nanoparticles, which are useful for drug delivery applications.