Preparation of lignin microcapsules via interfacial crosslinking using deep eutectic solution to dissolve lignin

Lignin is a biomacromolecule with multiple functional groups, which can be used as feedstocks for various functional materials. Lignin microcapsules with the crosslinked shell of lignin have potential applications in various fields. However, the use of toxic organic solvents for preparing lignin microcapsules poses a challenge. In this study, a green solvent called Deep Eutectic Solvent (DES, ChCl-LA) was employed for lignin dissolution. An emulsion of lignin was prepared using soybean oil with the DES dissolving lignin, and crosslinkers like PEGDE or epichlorohydrin facilitated the crosslinking of lignin at the emulsion interface. The resulting lignin microcapsules, with a size of ∼2 μm, were characterized using techniques such as optical microscopy, fluorescence microscopy, scanning electron microscopy, FT-IR, etc. For both NIR imaging and controlled release, the organic molecule BODPY was used as the template. The results demonstrate the successful preparation of size-controlled lignin microcapsules that can serve as nanocarriers for targeted organic molecules