Huan Siqi, Zhu Ya, Xu Wenyang, McClements David Julian, Bai Long, Rojas Orlando J
Key Laboratory of Bio-based Material Science and Technology of Ministry of Education, College of Material Science and Engineering, Northeast Forestry University, Harbin, Heilongjiang 150040, P. R. China.
Bioproducts Institute, Departments of Chemical & Biological Engineering, Chemistry, and Wood Science, The University of British Columbia, 2360 East Mall, Vancouver, British Columbia V6T 1Z3, Canada.
ACS Appl Mater Interfaces. 2021 Mar 17;13(10):12581-12593. doi: 10.1021/acsami.0c22560. Epub 2021 Mar 3.
We consider the variables relevant to adsorption of renewable nanoparticles and stabilization of multiphase systems, including the particle's hydrophilicity, electrostatic charge, axial aspect, and entanglement. Exploiting the complexation of two oppositely charged nanopolysaccharides, cellulose nanofibrils (CNFs) and nanochitin (NCh), we prepared CNF/NCh aqueous suspensions and identified the conditions for charge balance (turbidity and electrophoretic mobility titration). By adjusting the composition of CNF/NCh complexes, below and above net neutrality conditions, we produced sunflower oil-in-water Pickering emulsions with adjustable droplet diameters and stability against creaming and oiling-off. The adsorption of CNF/NCh complexes at the oil/water interface occurred with simultaneous partitioning (accumulation) of the CNF on the surface of the droplets in net negative or positive systems (below and above stochiometric charge balance relative to NCh). We further show that the morphology of the droplets and size distribution were preserved during storage for at least 6 months under ambient conditions. This long-term stability was held with a remarkable tolerance to changes in pH (, 3-11) and ionic strength (, 100-500 mM). The mechanism explaining these observations relates to the adsorption of the CNF in the complexes, counteracting the charge losses resulting from the deprotonation of NCh or charge screening. Overall, CNF/NCh complexes and the respective interfacial nanoparticle exchange greatly extend the conditions, favoring highly stable, green Pickering emulsions that offer potential in applications relevant to foodstuff, pharmaceutical, and cosmetic formulations.
我们考虑了与可再生纳米颗粒吸附及多相系统稳定性相关的变量，包括颗粒的亲水性、静电荷、轴向形状和缠结。利用两种带相反电荷的纳米多糖——纤维素纳米纤维（CNF）和纳米几丁质（NCh）的络合作用，我们制备了CNF/NCh水悬浮液，并确定了电荷平衡的条件（浊度和电泳迁移率滴定）。通过调整CNF/NCh络合物的组成，在净中性条件以下和以上，我们制备了水滴直径可调且具有抗分层和析油稳定性的向日葵水包油Pickering乳液。在油/水界面，CNF/NCh络合物的吸附伴随着CNF在净负或正系统（相对于NCh的化学计量电荷平衡以下和以上）中液滴表面的同时分配（积累）。我们进一步表明，在环境条件下储存至少6个月期间，液滴的形态和尺寸分布得以保留。这种长期稳定性在pH值（3 - 11）和离子强度（100 - 500 mM）变化时具有显著的耐受性。解释这些现象的机制与络合物中CNF的吸附有关，它抵消了因NCh去质子化或电荷屏蔽导致的电荷损失。总体而言，CNF/NCh络合物以及相应的界面纳米颗粒交换极大地扩展了条件，有利于形成高度稳定的绿色Pickering乳液，在食品、制药和化妆品配方等相关应用中具有潜力。
