Plant cell wall inspired lignin-based membrane with configurable radical scavenging activity

Abstract

Natural antioxidants have received considerable attention due to their inherent biocompatibility and biodegradability, yet inferior antioxidant, storage instability, and structural heterogeneity limit applications. Drawing inspiration from plant structures, we develop antioxidant membranes that are entirely biomass-derived, metal-free, and customizable, using the layer-by-layer (LBL) assembly technique. The natural polyphenolic lignin co-assembles with lauryl alcohol derived from cassia bark into macroporous spherical particles in a γ-valerolactone (GVL)/water mixture, in which the pore size can be facilely adjusted by modulating feed ratio. Furthermore, the lignin nanospheres’ free radical scavenging ability is greatly enhanced by enlarging the pore size, offering an alternative way to improve the antioxidant performance. As the hydrophilic shells of lignin spherical assemblies display a strong affinity towards holocellulose nanofibrils (HCNF), multilayered antioxidant membranes with stable mechanical strength are constructed. The entirely biomass-derived antioxidant membrane has proven effective in recycled antioxidative microfiltration applications, demonstrating more than 90 % scavenging activity over seven cycles. Moreover, it exhibits biodegradability even in harsh conditions, with temperatures below 280 K and relative humidity less than 30 RH%. This work illuminates new possibilities for applying natural antioxidants in precise control materials.