Direct Construction of Catechol Lignin for Engineering Long‐Acting Conductive, Adhesive, and UV‐Blocking Hydrogel Bioelectronics

Abstract

Long‐active conductivity, adhesiveness, and environmental stability are essential in the applications of hydrogel electronics. Integrating different functional materials into one system suffers from compatibility and cost problems. Inspired by the unique o‐methoxyl structure in polyphenol lignin and its binding role in plants, catechol lignin (DAL) is constructed by one‐step demethylation, which endows the lignin with a mussel‐like bioadhesion, good reducibility, as well as a high ultraviolet absorption. The DAL is then applied to reduced graphene oxide, and the products—the oxidized DAL and the reduced graphene oxide mixture (DAL/rGO) is added into a sodium alginate/polyacrylamide (SA/PAM) double network hydrogel. Based on the Schiff base reaction between the quinone of the oxidized DAL and the amino of the skin, the DAL/rGO incorporated hydrogels could stably adhere to the skin, and sensitively respond to physiological signals. In addition, the DAL could provide the hydrogels with long‐active sunscreen property when applied to real skin. These DAL based hydrogels have potential for on‐skin sensing and outdoor sport equipment.

Chemical Transformation of Lignosulfonates to Lignosulfonamides with Improved Thermal Characteristics

“…Such-prepared materials proved effective in scavenging the cationic dyes from the dyestuff effluents [28] and show great promise in the selective absorption of ofloxacin and ciprofloxacin [29]. Current studies also investigate the usage of the lignin-based prod-uct as wood adhesives for medium-density fiberboards [30] or functional hydrogels with conductive properties, with the potential to use them as a sunscreen or even flexible electronic skin [31]. The aforementioned studies show a great interest in utilizing lignin and its derivatives and exploring their potential as alternatives for many commercial products.…”

Ionic Flexible Sensors: Mechanisms, Materials, Structures, and Applications

“…IFS have also been applied in the biomedical fields owing to its good flexibility and biocompatibility to achieve remote and personalized health tests, including blood pressure monitoring, pulse monitoring, respiratory monitoring, and in vivo health monitoring. [273,274] In particular, IFS can be used as a non-invasive sensing device that can adapt to human skin and obtain accurate biological and physiological signals.…”

Polyphenol-based hydrogels: Pyramid evolution from crosslinked structures to biomedical applications and the reverse design

“…However, an aromatic unit usually contains only one phenolic hydroxyl group, which determines that natural lignin does not have obvious polyphenol properties. Therefore, abundant polyphenol units can be obtained by further demethylating to produce a series of polyphenol-related properties [ 60 , 61 ]. Through the redox reaction between lignin and high valence-state metal ions, ammonium persulfate can be induced to generate free radicals, which can lead to the polymerization of monomers such as acrylic acid and hydroxyethyl acrylamide, so as to prepare hydrogels without initiator [ 60 , 62 , 63 ].…”