Maestri C A, Bettotti P, Scarpa M
Nanoscience Laboratory, Department of Physics, University of Trento, Via Sommarive 14, I-38123 Povo TN, Italy.
J Mater Chem B. 2017 Oct 28;5(40):8096-8104. doi: 10.1039/c7tb01899a. Epub 2017 Oct 3.
In this study we investigated the fabrication of small hydrogel objects by the coordination-driven assembly of supramolecular rod-like crystallites of nanocellulose, using ionotropic gelation as a methodological approach and Ca as a gelling agent. We proved that the gelation process is diffusion-mediated and fitting the equations modelling this process to the profile of the Ca front, a Ca diffusion coefficient in the incipient hydrogel of (4.5 ± 1.1) × 10 cm s was calculated. At the steady-state a spatially homogeneous distribution of Ca-crosslinked sites in the hydrogel network was observed. External ionotropic gelation produced beads, wires or disks, while core-shell capsules were obtained by inverse ionotropic gelation. We demonstrated that equilibrium and dynamics of the distribution of Ca offer the opportunity to design precisely the size and shape of these small hydrogel objects. In particular, the core size and the shell thickness of the capsules can be tailored under kinetic controlled conditions. The proposed approach, with supramolecular structures of the natural source as assembling components and the water-in-water fabrication process, is fast, simple, and requires only sustainable chemistry and is easily implementable in automatic microfluidic platforms.
在本研究中，我们利用离子凝胶化作为一种方法，以钙作为胶凝剂，通过纳米纤维素超分子棒状微晶的配位驱动组装来研究小型水凝胶物体的制备。我们证明了凝胶化过程是扩散介导的，并将模拟该过程的方程拟合到钙前沿的轮廓，计算出初始水凝胶中钙的扩散系数为(4.5±1.1)×10⁻⁹ cm²/s。在稳态下，观察到水凝胶网络中钙交联位点的空间均匀分布。外部离子凝胶化产生珠子、线或盘，而通过反相离子凝胶化获得核壳胶囊。我们证明，钙分布的平衡和动力学为精确设计这些小型水凝胶物体的尺寸和形状提供了机会。特别是，胶囊的核尺寸和壳厚度可以在动力学控制条件下进行定制。所提出的方法以天然来源的超分子结构作为组装组件，并采用水包水制备工艺，快速、简单，仅需可持续化学方法，且易于在自动微流控平台上实现。
