Triggered Release from Cellulose Microparticles Inspired by Wood Degradation by Fungi

Triggered compound release has attracted considerable attention in recent years. However, the concepts and carriers reported for triggered release are often complex while nonapproved ingredients are mostly used to make the carriers. In this study, a bioinspired reactive oxygen species (ROS)-mediated delivery system, triggered by light, is introduced. We took inspiration from the well-known ROS mediated degradation of wood (cellulose) by brown-rot fungi and designed microparticles which consist of a core of cellulose nanocrystals, loaded with a drug, surrounded by a light sensitive shell. Incorporating indocyanine green, an FDA-approved photosensitizer, in the shell of the microparticles generates ROS upon NIR laser irradiation, which degrades the cellulose nanocrystals in the microparticles. It was revealed that doxorubicin, encapsulated in the cellulose core and used as a model compound in our study, becomes specifically released upon NIR irradiation of the microparticles. Attractive as well is that the microparticles are prepared by a simple one-step gas-shearing process and fully consist of compounds generally regarded as safe (GRAS).