Institute of Food Technology, University of Natural Resources and Life Sciences (BOKU), Muthgasse 18, 1190 Vienna, Austria.
Université Paris-Saclay, INRAE, AgroParisTech, UMR SayFood, 91300 Massy, France.
ACS Appl Mater Interfaces. 2024 Aug 21;16(33):43430-43450. doi: 10.1021/acsami.4c11035. Epub 2024 Aug 7.
Flocculation is a type of aggregation where the surfaces of approaching droplets are still at distances no closer than a few nanometers while still remaining in close proximity. In a high internal-phase oil-in-water (O/W) emulsion, the state of flocculation affects the bulk flow behavior and viscoelasticity, which can consequently control the three-dimensional (3D)-printing process and printing performance. Herein, we present the assembly of O/W Pickering high-internal-phase emulsions (Pickering-HIPEs) as printing inks and demonstrate how depletion flocculation in such Pickering-HIPE inks can be used as a facile colloidal engineering approach to tailor a porous 3D structure suitable for drug delivery. Pickering-HIPEs were prepared using different levels of cellulose nanocrystals (CNCs), co-stabilized using "raw" submicrometer-sized sustainable particles from a biomass-processing byproduct. In the presence of this sustainable particle, the higher CNC contents facilitated particle-induced depletion flocculation, which led to the formation of a mechanically robust gel-like ink system. Nonetheless, the presence of adsorbed particles on the surface of droplets ensured their stability against coalescence, even in such a highly aggregated system. The gel structures resulting from the depletion phenomenon enabled the creation of high-performance printed objects with tunable porosity, which can be precisely controlled at two distinct levels: first, by introducing voids within the internal structure of filaments, and second, by generating cavities (pore structures) through the elimination of the water phase. In addition to printing efficacy, the HIPEs could be applied for curcumin delivery, and release kinetics demonstrated that the porous 3D scaffolds engineered for the first time using depletion-flocculated HIPE inks played an important role in 3D scaffold disintegration and curcumin release. Thus, this study offers a unique colloidal engineering approach of using depletion flocculation to template 3D printing of sustainable inks to generate next-generation porous scaffolds for personalized drug deliveries.
絮凝是一种聚集类型，其中接近的液滴表面之间的距离仍然不小于几个纳米，同时仍然保持近距离。在高内相比水包油 (O/W) 乳液中，絮凝状态会影响整体流动行为和粘弹性，从而控制三维 (3D) 打印过程和打印性能。在这里，我们展示了 O/W Pickering 高内相比乳液 (Pickering-HIPE) 的组装作为打印墨水，并展示了如何在这种 Pickering-HIPE 墨水中进行耗尽絮凝，作为一种简单的胶体工程方法来定制适合药物输送的多孔 3D 结构。Pickering-HIPE 是使用不同水平的纤维素纳米晶体 (CNC) 制备的，并用生物质加工副产物中的“原始”亚微米级可持续颗粒进行共稳定。在这种可持续颗粒存在的情况下，较高的 CNC 含量促进了颗粒诱导的耗尽絮凝，从而形成了机械坚固的凝胶状墨水体系。尽管如此，由于存在吸附在液滴表面的颗粒，即使在如此高度聚集的体系中，液滴也能稳定地防止聚结。从耗尽现象产生的凝胶结构使能够制造具有可调孔隙率的高性能打印物体，并且可以在两个不同水平上进行精确控制：首先，通过在纤维内部结构中引入空隙，其次，通过消除水相来产生空腔（孔结构）。除了打印效果外，HIPE 还可以用于姜黄素的输送，并且释放动力学表明，首次使用耗尽絮凝 HIPE 墨水设计的多孔 3D 支架在 3D 支架的崩解和姜黄素的释放中发挥了重要作用。因此，本研究提供了一种独特的胶体工程方法，即使用耗尽絮凝来模板化可持续墨水的 3D 打印，以生成用于个性化药物输送的下一代多孔支架。
