Rational Design and Synthesis of Lignin‐Derived Smart Sunscreens

Abstract

Lignin exhibits a long‐active UV‐blocking property due to its macromolecular aromatic structure and unique semiquione‐quione‐hydroquione transition. However, its poor absorbance in UVA region (320–400 nm) and irregular aggregation are still the obstacles. Herein, active spirapyrane (SP‐Br) is synthesized and covalently introduced into alkali lignin (AL) to construct photo‐stimulated UV‐absorbing enhancement sunscreen actives (AL‐SPn). The introduction of SP significantly improved the absorbance of AL in UVA region and its aggregation is effectively eased. When the optimal AL‐SP3 solution is exposed to UV irradiation, the color turned purple, and the absorbance in UVA region further improved as the unconjugated SP transformed into conjugated merocyanine (MC) structure. When the light is removed, the solution recovered light yellow. The antioxidant property of AL endow the reversible SP‐MC transformation with good cyclic stability. As‐prepared AL‐SP3 based sunscreen exhibit obvious photo‐stimulated enhancement effect. The sun protection factor (SPF) improved from 23 to 89 after 4 h irradiation, and can maintain the high performance for another 8 h. In addition, it exhibit low permeation and good biocompatibily in vitro and vivo, demonstrating its good potential in practical use.

Whiten Lignin-Based Sunscreen via Fractionation and Ultrasonic Cavitation

“…Lignin is the second largest component of plants after cellulose . It is composed of three p-hydroxyphenylpropane units, which absorb UV irradiation and scavenge free radicals. − Hence, lignin is an ideal natural material for UV protection, especially under the stabilization of the three-dimensional network structure. , Several efforts have been devoted to developing lignin-based sunscreens since our first try by blending lignin with commercial products . However, the issue of dark color is still an obstacle, severely limiting the application of lignin-based sunscreens.…”

Facile Strategy to In Situ Synthesize Gallic Acid-Modified Lignin and Its Utilization for Fabricating Conductive and Self-Adhesive Hydrogels as Strain Sensors

“…However, the exorbitant cost of polydopamine (PDA) hydrogels restricts their practical application. In comparison, lignin, the second most abundant component in plants, is rich in phenolic hydroxyl groups and phenyl rings, and it is used widely in various fields, such as adhesives, − optical switching, nanomaterials, and hydrogels. , Despite significant progress, the heterogeneity and low reactivity of lignin severely limit its applications. Previously, chemical modification, functionalization, or nanotechnology enhanced lignin’s reactivity and performance.…”

Green Nanocellulose/PEI‐Grafted Magnetic Nanoparticles for Effective Removal of Heavy Metal Ions

“…[7] Lignocellulose has consistently served as a versatile and plentiful raw resource, displaying significant promise for utilization across various sectors, including the food, [8] polymer, [9] cosmetics, [10] agriculture, [11] and biotechnology industries. [12] Nanocellulose-based materials have emerged as promising candidates for pollutant removal. One such material is cellulose nanofibrils (CNFs), obtained by mechanically breaking down pulp.…”