Biocompatible Lignin-Containing Hydrogels with Self-Adhesion, Conductivity, UV Shielding, and Antioxidant Activity as Wearable Sensors

Abstract

Hydrogels have drawn intensive attention as emerging materials for various applications in wearable sensors, soft robotics, and implantable devices. However, fabricating hydrogels with UV-shielding and antioxidant properties still remains a challenge. Herein, we prepared biocompatible 3-allyloxy-2-hydroxypropyl-lignin/polyacrylic acid (AHP-lignin/PAA) hydrogels with self-adhesion, conductivity, UV shielding, and antioxidant activity as wearable sensors by the incorporation of lignin into PAA. The structure, lap shear strength, and biocompatibility were characterized using the UV–vis spectrometer, universal testing machine, and cell test. The hydrogels showed strong adhesion to various substrates. The AHP-lignin/PAA hydrogels had excellent UV shielding and free radical scavenging capacity. Meanwhile, AHP-lignin/PAA hydrogels exhibited excellent sensitivity to tiny changes in low pressure. Notably, the hydrogels could adhere to the skin well without any other adhesives to monitor the movement signals of the body motion accurately. The biocompatible AHP-lignin/PAA hydrogels with self-adhesion, conductivity, UV shielding, and antioxidant activity offer great potential applications in wearable sensors.

Uniformly Dispersed Poly(lactic acid)-Grafted Lignin Nanoparticles Enhance Antioxidant Activity and UV-Barrier Properties of Poly(lactic acid) Packaging Films

“… 12 − 14 Every year, 70 million tons of lignin are isolated as byproducts of the paper and pulp industry, and most of it is burned as a low-value fuel. 15 , 16 In addition to being biocompatible 17 − 19 and providing antioxidant activity, lignin also absorbs UV-light and thus allows to impart UV-barrier properties on food packaging materials. 19 − 22 …”

“… 15 , 16 In addition to being biocompatible 17 − 19 and providing antioxidant activity, lignin also absorbs UV-light and thus allows to impart UV-barrier properties on food packaging materials. 19 − 22 …”

“…A drawback of these antioxidants, however, is that they may lead to the generation of carcinogenic compounds, resulting in other adverse side effects on human health, such as allergies caused by benzoic acid, nitrates, and sulfites. , To overcome these challenges, there is a growing interest in exploring natural antioxidants from plant leaves, spices, and herbs, which are presumably safer for human consumption. One interesting sustainable and low-cost alternative to non-renewable toxic antioxidants is lignin. − Every year, 70 million tons of lignin are isolated as byproducts of the paper and pulp industry, and most of it is burned as a low-value fuel. , In addition to being biocompatible − and providing antioxidant activity, lignin also absorbs UV-light and thus allows to impart UV-barrier properties on food packaging materials. − …”

Assessing the Potential of New Lignin-Based pH-Responsive Nanoparticles as Drug Carriers for Cancer Treatment

“…Lignin could improve the mechanical properties of plants and enhance their resistance to the surrounding environment . It has been widely used in low valued-added products including fillers, additives, binders, or surfactants. , Moreover, because of its specific structure, lignin shows several properties such as low cytotoxicity, UV-blocking property, antibacterial properties, , antioxidant properties, , and self-assembly capabilities …”

“…9 It has been widely used in low valued-added products including fillers, additives, binders, or surfactants. 10,11 Moreover, because of its specific structure, lignin shows several properties such as low cytotoxicity, 12 UV-blocking property, 13 antibacterial properties, 14,15 antioxidant properties, 16,17 and self-assembly capabilities. 18 As far as we know, only a few studies reported lignin-based NPs for cancer therapy.…”