Natural Shape-Retaining Microcapsules With Shells Made of Chitosan-Coated Colloidal Lignin Particles

Abstract

Thin film coating of charged nanoparticles with oppositely charged polymers is an efficient and straightforward way for surface modification, but synthetic polyelectrolytes should be replaced by abundant biopolymers. In this study a thin film of chitosan was adsorbed onto colloidal lignin particles (CLPs) that were then systematically studied for olive oil stabilization with an objective to develop shape-retaining microcapsules that comprised of only renewable biomaterials. Full surface coverage was achieved with merely 5 wt% of chitosan relative to the dry weight of CLPs, reversing their surface charge from negative to positive. Such modification rendered the chitosan-coated particles excellent stabilizers for forming Pickering emulsions with olive oil. The emulsion droplets could be further stabilized by sodium triphosphate that provided ionic intra- and inter-particle cross-linking of the chitosan corona on the CLPs. Following the optimum conditions, the non-cross-linked microcapsules exhibited a strong stability against coalescence and the electrostatically stabilized ones additionally retained their shape upon drying and rewetting. Non-cross-linked microcapsules were used to demonstrate encapsulation and rapid release of ciprofloxacin as a model lipophilic drug in aqueous media. Overall, the combination of antimicrobial chitosan and antioxidative lignin nanoparticles hold unprecedented opportunities as biocompatible and biodegradable materials for controlled drug delivery.

Spherical lignin particles: a review on their sustainability and applications

“…Cationic lignin particles (ζ potential ca. +30 mV) can be easily prepared by adsorption of synthetic (PDADMAC) 35,37 or natural polycations (chitosan) 45 or cationized lignin. 47 Such versatility enables the use of spherical lignin particles as dispersants for mineral particles with either negative or positive charges.…”

Strategies for structuring diverse emulsion systems by using wood lignocellulose-derived stabilizers

“…131 Kraft lignin nanoparticles were also coated with chitosan, used as emulsifiers, and further crosslinked with sodium triphosphate to achieve a strong stability against emulsion coalescence. 132 Recent efforts in lignin nanoparticle research tackle the challenge of their continuous production by using a microchannel 126 and a potentially scalable preparation by spray-freezing. 133 4.2.4.…”

Biocatalytic Hybrid Nanoparticles for Degassing and Stabilization of Single Electron Transfer-Living Radical Polymerization in Pickering emulsions

“…[29] The resulting LNPs (diameter 97 nm) were used to adsorb chitosan (10 wt% relative to LNPs) as a cationic polyelectrolyte. As previously reported, [28] we obtained colloidally stable cationic chitosan-coated LNPs (chi-LNPs) (ζ-potential + 32 mV and diameter 190 nm) that were here used to adsorb GOx (10 mg g-1 chi-LNPs) to yield the enzyme-immobilized LNPs (GOx-chi-LNPs) ( Figure S1 and S2). The increase in size and surface charge as determined by dynamic light scattering (DLS) analysis of the resulting particles after the two-step adsorption procedure (215 nm and + 41 mV) veri ed an effective electrostatic interaction between GOx and chi-LNPs ( Fig.…”

“…LNPs used in this work were produced following the same procedure described earlier with a few modi cations. [28] Brie y, kraft lignin was dissolved in acetone/water mixture (mass ratio 3:1), insoluble impurities were removed by ltration, and LNPs produced by rapid pouring of deionized water to lignin solution followed by rotary evaporation of acetone. The nal aqueous dispersion of LNPs (0.4 wt%) was obtained with a lignin mass yield of 89%.…”

“…Here we report a multifunctional Pickering emulsion stabilizer that enables e cient SET-LRP of waterimmiscible vinyl monomers without extra degassing steps and at a broad temperature range. Lignin nanoparticles (LNPs) coated with cationic polymers act as the carrier for GOx because of their recently reported bene cial properties in stabilization of Pickering emulsions [27] [28] and enzyme immobilization. [29] [30] In addition to investigating the ability of the system to scavenge the in situ generated hydrogen peroxide and produce well-de ned polymers, we also explore the obtained latex dispersions for the preparation of lignin-based composites.…”