Udoh Christiana E, Cabral João T, Garbin Valeria
Department of Chemical Engineering, Imperial College London, London SW7 2AZ, UK.
Sci Adv. 2017 Dec 8;3(12):eaao3353. doi: 10.1126/sciadv.aao3353. eCollection 2017 Dec.
The precise spatiotemporal delivery of nanoparticles from polymeric capsules is required for applications ranging from medicine to materials science. These capsules derive key performance aspects from their overall shape and dimensions, porosity, and internal microstructure. To this effect, microfluidics provide an exceptional platform for emulsification and subsequent capsule formation. However, facile and robust approaches for nanocomposite capsule fabrication, exhibiting triggered nanoparticle release, remain elusive because of the complex coupling of polymer-nanoparticle phase behavior, diffusion, phase inversion, and directional solidification. We investigate a model system of polyelectrolyte sodium poly(styrene sulfonate) and 22-nm colloidal silica and demonstrate a robust capsule morphology diagram, achieving a range of internal morphologies, including nucleated and bicontinuous microstructures, as well as isotropic and non-isotropic external shapes. Upon dissolution in water, we find that capsules formed with either neat polymers or neat nanoparticles dissolve rapidly and isotropically, whereas bicontinuous, hierarchical, composite capsules dissolve via directional pulses of nanoparticle clusters without disrupting the scaffold, with time scales tunable from seconds to hours. The versatility, facile assembly, and response of these nanocomposite capsules thus show great promise in precision delivery.
从医学到材料科学等诸多应用都需要聚合物胶囊实现纳米颗粒精确的时空递送。这些胶囊的关键性能取决于其整体形状、尺寸、孔隙率和内部微观结构。为此，微流体技术为乳化及后续胶囊形成提供了一个卓越的平台。然而，由于聚合物 - 纳米颗粒相行为、扩散、相转变和定向凝固之间的复杂耦合，制备具有触发式纳米颗粒释放功能的纳米复合胶囊的简便且可靠的方法仍然难以实现。我们研究了聚电解质聚苯乙烯磺酸钠和22纳米胶体二氧化硅的模型体系，并展示了一个可靠的胶囊形态图，实现了一系列内部形态，包括成核和双连续微观结构，以及各向同性和非各向同性的外部形状。在水中溶解时，我们发现由纯聚合物或纯纳米颗粒形成的胶囊会快速且各向同性地溶解，而双连续、分级的复合胶囊则通过纳米颗粒簇的定向脉冲溶解，且不会破坏支架结构，时间尺度可从几秒调整到几小时。因此，这些纳米复合胶囊的多功能性、简便组装性和响应性在精确递送方面显示出巨大潜力。
