Lignin-based hydrogel offers breakthrough in controlled drug release and wound healing
New smart hydrogel integrates lignin’s natural strength and bioactivity for safer, longer-lasting biomedical applications
image: Lignin-Based Hydrogel Offers Breakthrough in Controlled Drug Release and Wound Healing New smart hydrogel integrates lignin’s natural strength and bioactivity for safer, longer-lasting biomedical applications
Credit: Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, International Innovation Center for Forest Chemicals and Materials, Nanjing Forestry University, Nanjing
A research team has unveiled a new type of hydrogel that leverages the natural properties of lignin to create a multifunctional material suitable for biomedical applications, particularly in wound healing and drug delivery. The study, published in the Journal of Bioresources and Bioproducts, introduces a polyvinyl alcohol/chitosan/sulfonated lignin (PVA-CS-L) hydrogel that not only improves mechanical performance but also offers controlled and pH-responsive release of bioactive lignin.
Lignin, a complex organic polymer found in plant cell walls, is known for its antioxidant and antimicrobial properties. However, its rapid release or accumulation in biological systems can lead to toxicity. To address this, the researchers designed a hydrogel system that incorporates lignin through non-covalent interactions—such as hydrogen bonding, van der Waals forces, and electrostatic interactions—allowing for a more controlled release profile.
The resulting hydrogel demonstrated improved mechanical strength, with tensile strength increasing to 36 kPa and compressive strength reaching 900 kPa, outperforming traditional PVA-CS hydrogels. The material also showed high compressive toughness (up to 9.0 MJ/m³), making it more resilient under physical stress.
One of the key innovations of the study is the pH-sensitive release mechanism. In slightly acidic environments (pH 5.5), such as those found in healthy wounds, the hydrogel releases lignin slowly. However, in more alkaline conditions (pH 7.4), which are typical of infected or chronic wounds, the release rate increases significantly. This behavior is attributed to the electrostatic interactions between the positively charged chitosan and the negatively charged lignin, which weaken as pH increases.
In addition to lignin release, the hydrogel was tested for its ability to deliver epigallocatechin gallate (EGCG), a polyphenol with known antioxidant and antimicrobial properties. The presence of lignin enhanced the sustained release of EGCG, suggesting a synergistic effect between the two bioactive compounds. The hydrogel also exhibited strong antioxidant activity, effectively scavenging reactive oxygen species (ROS), and showed significant antibacterial effects against Staphylococcus aureus, a common wound pathogen.
Biocompatibility tests using 3T3-L1 cells confirmed that the hydrogel extracts promoted cell proliferation and showed no cytotoxic effects, even at high concentrations. These results indicate that the material is safe for biomedical use and may even support tissue regeneration.
The study highlights the potential of lignin—not just as a structural component but as an active biomedical agent—when integrated into smart hydrogel systems. The researchers suggest that this approach could lead to the development of next-generation wound dressings that are not only mechanically robust but also biologically responsive, offering on-demand drug release based on the wound environment.
This work adds to a growing body of research exploring the high-value applications of lignin in medicine and biotechnology. By combining natural polymer chemistry with advanced materials science, the team has opened new avenues for sustainable, effective, and low-cost healthcare solutions.