Sustainable Strategies in the Synthesis of Lignin Nanoparticles for the Release of Active Compounds: A Comparison

Abstract

The preparation of nanoparticles represents a powerful tool for lignin valorization, as it combines easy methodologies with high application potential. Different synthetic strategies and various lignin sources have been employed in the process. However, the great variability in the lignin structure prevents a direct comparison of the so far reported lignin nanoparticles (LNPs), especially as regards their physicochemical and functional properties. To this purpose, two green protocols, that is, solvent‐antisolvent and hydrotropic, were optimized and used to generate LNPs from the same softwood kraft lignin. The nanomaterials were fully characterized to extrapolate structure/property relationships and reveal any differences in the mechanism of self‐assembly. Furthermore, tests on methylene blue entrapment capacity and release behavior at two different pH values (2.0 and 7.4) evidenced a clear dependence on the LNPs characteristics and thus on the strategy adopted for their production.

Circular Hazelnut Protection by Lignocellulosic Waste Valorization for Nanopesticides Development

“…Very recently, lignin-based polymers have also attracted the interest of the research community: indeed, lignin can be used as a low-cost, eco-friendly reinforcement to prepare high-performance nanocomposites [42][43][44]. Different nanoscale lignin compounds can be synthesized by different chemical/physical approaches [45][46][47]. Lignin nanoparticles (LNP), thanks to their antioxidant activity and other characteristics, can find applications both as active ingredients and as a nanocarrier structure [48,49].…”

Recent Advances in Synthesis and Degradation of Lignin and Lignin Nanoparticles and Their Emerging Applications in Nanotechnology

“…In the second method of acidic precipitation the LiG NPs were synthesized in a high-pH aqueous solution. These LiG NPs showed stability only at an acidic pH [ 65 ].…”

“…In this method, the nature of the solvent and various non-covalent interaction forces play a significant role in the agglomerate and self-assembled of LiG NPs. The significant non-covalent interaction that forces their bond energies are π-π interactions (4 to 30 kJmol −1 ), hydrogen-bonding (4 to 30 kJmol −1 ), van der Waals forces (1 to 4 kJmol −1 ) and chain entanglement [ 65 , 69 ]. In the self-assembly process, cyclohexane (CHX) is incorporated into the lignin solution of alkaline pH.…”

A tunable deep eutectic solvent-based processing for valorization of chestnut wood fiber as a source of ellagic acid and lignin

“…This applies in particular to phenolic polymers, mainly tannins and lignin, which have been exploited in a variety of sectors [14]. As an example, tannins are largely used to implement antioxidant functional coatings [15][16][17] or as antimicrobial agents for the control of bacteria growth in food packaging [18], whereas lignin has been widely exploited as a green additive to improve the mechanical and functional properties of polymeric matrices for tissue engineering [19], drug delivery [20], diagnostics [21], food packaging [22], and environmental applications [23].…”