Nano- and microencapsulation of active substances with controlled release in biocompatible matrices has been the subject of numerous scientific efforts, especially for biomedical applications. Notwithstanding its structural complexity and variability, lignin represents one of the most suitable materials for the generation of nano- and microcapsules capable to efficiently entrap and deliver the drug. This is made possible thanks to the high self-aggregating ability of the lignin molecules. Additionally, besides the known biocompatibility, antimicrobial and antioxidant capacity ensure an efficient protection of the compound. Last, but not least, the direct generation of nanostructures from technical lignins is highly attractive because it allows for the exploitation of their peculiar characteristics without the need for time-consuming and costly pre-treatments.<br/>The present contribution will highlight our latest advances in the field of lignin-based microcapsules (LMCs) for the transport and controlled release of lipophilic molecules. Starting from softwood lignosulfonate, LMCs have been prepared by a simple, green and easily scalable ultrasound-assisted strategy. Time-dependent release of the active and capsule stability under different environments (e.g. salinity, pH) were evaluated, taking into account various lignin/active ratios and the effect of <i>ad hoc</i> prepared additives to enable triggered disassembly of the capsule shell. Morphological and structural characterizations were carried out as well to extrapolate structure-property relationships. In addition, to demonstrate their potential for topical purposes, the kinetic of release of thymol derivatives in acetate buffer at pH 5.4 (to simulate skin pH) have been investigated.

Stimuli-responsive lignin microcapsules for the targeted release of actives

ACS Spring 2022

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