Electrostatic Interaction-Based Fabrication of Calcium Alginate–Zein Core–Shell Microcapsules of Regulable Shapes and Sizes

• DOI: 10.1021/acs.langmuir.1c01098
• Publication Date: 2021-08-24T14:28:03Z
• Authors: Xun Zhang; Bing Hu; Yiguo Zhao; Yisu Yang; Zhiming Gao; Katsuyoshi Nishinari; Jixin Yang; Yin Zhang; Yapeng Fang
• Keywords: 0404 agricultural biotechnology; Alginates; Zein; Static Electricity; QD; Capsules; 04 agricultural and veterinary sciences; Q1; Hydrophobic and Hydrophilic Interactions

Core-shell microcapsules with combined features of hydrophilicity and hydrophobicity have become much popular. However, the assembly of biocompatible and edible materials in hydrophilic-hydrophobic core-shell microcapsules is not easy. In this work, based on electrostatic interactions, we prepared controllable calcium alginate (ALG)-zein core-shell particles of different shapes and sizes using hydrophilic ALG and hydrophobic zein by a two-step extrusion method. Negatively charged hydrogel beads of spherical, ellipsoidal, or fibrous shape were added into a positively charged zein solution (dissolved in 70% (v/v) aqueous ethanol solution) to achieve different-shaped core-shell particles. Interestingly, the size, shape, and shell thickness of the particles can be regulated by the needle diameter, stirring speed, and zein concentration. Moreover, for simplification, the core-shell particles were also synthesized by a one-step extrusion method, in which an ALG solution was added dropwise into a 70% (v/v) aqueous ethanol solution containing zein and CaCl2. The particles synthesized in this work showed controlled digestion of encapsulated medium-chain triglyceride (MCT) and sustained release of encapsulated thiamine and ethyl maltol. Our preparation method is simplistic and can be extended to fabricate a variety of hydrophilic and hydrophobic core-shell structures to encapsulate a broad spectrum of materials.