posted on 2023-05-02, 02:43authored bySang-Mook You, June-Ho Choi, Kyung-An Kim, Hoyong Kim, Hyun Gil Cha
The aromatic polymer kraft lignin
(KL) is an effective UV absorber
that has recently emerged as a promising natural candidate for UV
radiation filters in cosmetics. However, despite the excellent UV-blocking
performance of KL, its dark color owing to chromophores and low solubility
in aqueous environments are significant bottlenecks to its use in
practical UV-shielding applications. Herein, the intrinsic problems
associated with the color and dispersity of KL were resolved by fabricating
a composite matrix of KL with short-chain glucan (SCG), which was
obtained from the enzymatic cleavage of amylopectin in waxy maize
starch, to employ its white color and hydrophilic nature; the composite
matrix was fabricated via self-assembly into spherical microcapsules
without the need for any toxic solvent or chemical modifications.
We utilized the characteristics of the intermolecular interactions
between KL and SCG which enabled their solubility in the aqueous γ-valerolactone/double-distilled
water binary solvent. Notably, the J-aggregation state of KL allows
for the even distribution of KL within the composite, significantly
improving the UV-blocking properties with a broad absorption range
and a UVA/UVB ratio of 0.9 at the critical wavelength (λc) of 387 nm, which are sufficient for practical use as a UV-blocking
filter.