Preparation and characterisation of lignin nanoparticles: evaluation of their potential as antioxidants and UV protectants

Abstract

Lignin, an abundant plant biopolymer, is known to possess antioxidant and UV protectant properties in its native state. Nanoparticles exhibit either improved or different properties corresponding to their bulk materials or parent polymers. In the present study, using nanoprecipitation method, dioxane lignin nanoparticles (DLNP) and alkali lignin nanoparticles (ALNP) are fabricated from two different sources of lignin, i.e., hardwood dioxane lignin (DL) extracted from subabul stems and softwood alkali lignin (AL) which is available as a commercial source. Both DLNP and ALNP were fabricated in spherical shape with mean size of 80À104 nm. Analysis of radical scavenging activity revealed that both DLNP and ALNP possess higher antioxidant activity when compared with their parent polymers DL and AL, respectively. UV protectant potential of DLNP and ALNP was validated by monitoring the survival rates of Escherichia coli upon UVinduced mortality. DLNP and ALNP were more efficient than DL and AL in protecting E. coli against UV-irradiation-induced mortality. However, upon irradiation for different time periods, DLNP offered pronounced protection for E. coli against UV when compared with ALNP. Thus, the present study demonstrates that the antioxidant and UV protection properties of DLNP can be exploited further in food, pharmaceutical and cosmetic industries.

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

“…The abundance and relatively low cost of lignin in combination with its antioxidant activity and UV‐shielding properties attract renewed interest in this natural polyphenol. The main lignin types available in relevant quantities are lignosulfonates (LSs), kraft lignin (KL), organosolv lignins (OSLs), and biorefinery lignins that differ notably in their chemical structure, molecular weight, and purity, which in turn determine their solubility and organoleptic qualities.…”

“…Lignin is a fascinating biopolymer with a high valorization potential. Besides being the most abundant aromatic renewable biopolymer, its complex structure is responsible for its antioxidant and antimicrobial activity . Lignins arise from the plants’ secondary metabolism of 4‐hydroxyphenylpropanoid precursors that differ in the number of methoxy groups at the 3‐ and 5‐positions of the phenolic ring .…”

Safe nanotechnologies for increasing the effectiveness of environmentally friendly natural agrochemicals

“…Lignins are cross‐linked polymers of phenolic compounds that are constituents of the plant cell walls. Nanoprecipitation methods with lignin produce nanoparticles that protect the coated materials against corrosive agents and degradation by UV and oxidants . They can increase the efficacy of herbicide application and they open interesting possibilities for protecting natural compounds against degradation by external agents.…”

Lignin for polymer and nanoparticle production: Current status and challenges

“…However, the poor compatibility of technical lignin with other polymer matrices hinders its application as a UV absorber. LNPs not only improve the compatibility and dispersion but also possess significant UV protectant activity when compared with regular lignins . The mechanical and thermal performance of the LNPs/PVA films was improved owing to adequate interfacial adhesion between phenolic hydroxyl groups on the shell of LNPs with PVA matrix through hydrogen bonding .…”