Facile, High-Yield, and Freeze-and-Thaw-Assisted Approach to Fabricate Bamboo-Derived Hollow Lignocellulose Microcapsules for Controlled Drug Release

Microcapsules have attracted considerable attention on account of their fundamental values in the storage and release of various cargoes. However, most microcapsules derived from synthetic polymers are nondegradable and have a risk of microplastic pollution. Therefore, the development of renewable alternatives has become an increasingly attractive area in recent years. Herein, hollow lignocellulose microcapsules (LMs) derived from discarded parenchyma cells of moso bamboo, which are biodegradable, low-cost, and eco-friendly, were prepared by delignification and freezing-and-thawing (FAT) processes. The yield of monodispersed LMs on the delignified bamboo was up to 24.89%, which reserved native cell structures with cellulose nanofibers and hierarchical porous structures. Owing to their higher specific surface area and O/C value, LMs exhibited an excellent encapsulation efficiency of 92.2% by using doxorubicin hydrochloride (DOX) as a model drug. A pH-responsive release profile of DOX at the pH of 3.4 and 6.8 was achieved due to the protonation of drugs and carriers trigged in acidic conditions. Finally, after embedding LMs@DOX in alginate beads to prevent the initial burst release, a sustained release behavior for DOX was realized. Our work provides a more sustainable alternative to microencapsulation and enables a high-value-added utilization of bamboo wastes.