Lignin for Nano‐ and Microscaled Carrier Systems: Applications, Trends, and Challenges

Abstract

To liberate society from its dependence on fossil‐based fuels and materials it is pivotal to explore components of renewable plant biomass in applications that benefit from their intrinsic biodegradability, safety, and sustainability. Lignin, a byproduct of the pulp and paper industry, is a plausible material for carrying various types of cargo in small‐ and large‐scale applications. Herein, possibilities and constraints regarding the physical–chemical properties of the lignin source as well as modifications and processing required to render lignins suitable for the loading and release of pesticides, pharmaceuticals, and biological macromolecules is reviewed. In addition, the technical challenges, regulatory and toxicological aspects, and future research needed to realize some of the promises that nano‐ and microscaled lignin materials hold for a sustainable future are critically discussed.

Lignosulfonate Microcapsules for Delivery and Controlled Release of Thymol and Derivatives

“…In this scenario, entrapment, in various forms of actives in matrices made of natural polymers, represents an interesting approach; numerous efforts have been published in this direction, using practically every type of natural polymer physically and chemically suitable [5]. Lignin, in this respect, possesses key features to be part of this gathering, as has been recently summarized [6].…”

“…chemically suitable [5]. Lignin, in this respect, possesses key features to be part of this gathering, as has been recently summarized [6].…”

“…Encapsulation by sonication is a recently developed technique for the synthesis of natural polyphenols microcapsules that requires minimum amounts of time for preparation and only generates minimum amounts of aqueous waste [6,8,12,17]. The energy evolved during sonication can, in fact, trigger supramolecular stacking interaction in natural polyphenolic macromolecules, such as tannins or lignins, most noteworthy also without the addition of crosslinking, and thus eventually only additionally stabilizing agents [18][19][20].…”

“…The energy evolved during sonication can, in fact, trigger supramolecular stacking interaction in natural polyphenolic macromolecules, such as tannins or lignins, most noteworthy also without the addition of crosslinking, and thus eventually only additionally stabilizing agents [18][19][20]. This allowed for the generation of different families of capsules for controlled stimuli responsive active release under different conditions [6,8,17,21,22]. Tuning of the sonication power allows for either simple stacking or, under higher power treatments, crosslinks between the macromolecule chains to generate thicker capsules.…”

“…Such materials show high stability, not only in the isolated form, but also in cosmetic media and, therefore, are interesting vectors for innovative formulation in health, personal care, and cosmetics. The structural features of LSs also render them optimal shell components for water-dispersible nano-and microcapsules that can be generated easily while using ultrasonication and are suitable for hosting rather water-insoluble actives [6,23]. Thymol (T) is a natural-derived monoterpenoid phenolic substrate.…”