Tannic acid/poly(vinyl alcohol)-modified chitosan/bacterial cellulose composite membranes with enhanced surface hydrophilicity and wet-state stability for anti-adhesion applications
This study demonstrates that modifying chitosan/bacterial cellulose membranes with a tannic acid/poly(vinyl alcohol) coating significantly enhances surface hydrophilicity and reduces fibroblast adhesion while maintaining robust wet-state mechanical stability, resulting in a highly effective anti-adhesion barrier that completely prevented postoperative adhesions in a mouse model.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
After abdominal or pelvic surgery, the body's natural healing process can sometimes go too far. When tissues are injured, the body sends proteins and cells to repair the damage, but this response can cause internal organs to stick together in unwanted ways. These internal scars, known as adhesions, can lead to chronic pain, bowel blockages, or infertility, and they often make future surgeries much more difficult and dangerous. To prevent this, doctors use physical barriers—thin sheets or gels placed between injured tissues—to keep them apart while they heal. However, creating a barrier that works well is a delicate balancing act. It must be strong enough to stay intact in the wet, salty environment of the human body, yet soft enough to conform to irregular surfaces. Crucially, its surface must be slippery and water-loving enough to stop cells from grabbing onto it and forming new scars. If the barrier dissolves too quickly, swells up and loses its shape, or feels too rough to the touch, it fails to do its job.
Researchers at Zhengzhou University and the Beijing University of Chemical Technology have developed a new type of barrier membrane that addresses these challenges by combining two natural materials and adding a special surface coating. They started with chitosan, a substance derived from shellfish shells that is gentle on the body, and mixed it with bacterial cellulose, a pure form of fiber produced by bacteria that is known for its strength. By blending these two, they created a base sheet that was tough enough to hold its shape when wet but still flexible. To make the surface even better, they dipped these sheets into a solution containing tannic acid, a compound found in tea and wine, and poly(vinyl alcohol), a common water-soluble plastic. This coating process was designed to make the membrane surface extremely smooth and water-attracting, which helps it slide easily against tissues and discourages cells from sticking.
The team tested membranes with different amounts of bacterial cellulose to find the perfect base, settling on a mixture containing ten percent bacterial cellulose. They then varied the time the membranes spent in the coating solution, ranging from six to twenty-four hours, to see how long the treatment needed to be to achieve the best results. The goal was to find a version that became very slippery and water-loving without losing its strength or falling apart in water. They discovered that soaking the membranes for eighteen hours produced the ideal balance. This specific membrane, which they named CBTP18, became so water-loving that a drop of water spread out almost completely flat on its surface, whereas the uncoated version repelled water like a waxed car. At the same time, the surface became incredibly smooth, with a friction level so low it was comparable to a well-lubricated surface, allowing it to glide easily.
Despite these dramatic changes to the surface, the membrane remained remarkably strong. When tested in a liquid environment that mimics the human body, the coated membrane retained nearly all of its original strength, holding together under pressure just as well as the uncoated version. It also showed great stability over time; after sitting in a saltwater solution for thirty-five days, it kept about seventy-one percent of its original mass, proving it would not dissolve away before the healing was complete. The researchers also checked how safe the material was for the body. They found that it did not damage red blood cells and that living cells grew well on it, showing no signs of toxicity. Most importantly, the coating successfully reduced the number of cells that attached to the surface. In laboratory tests, the number of fibroblasts—cells responsible for building scar tissue—that stuck to the coated membrane dropped by more than half compared to the uncoated version.
To see if these laboratory results held up in a living organism, the researchers tested the membrane in mice. They created a surgical injury model where the abdominal wall and the cecum, a part of the intestine, were scratched to simulate trauma. In the group of mice that received no treatment, four out of six developed visible adhesions where the tissues had stuck together. In stark contrast, none of the six mice treated with the new membrane developed any visible adhesions. When the researchers examined the tissues under a microscope, they found that the treated areas healed cleanly with minimal inflammation, and the membrane itself remained intact without breaking or deforming. The study suggests that this combination of a strong, natural base and a slippery, water-loving coating creates a barrier that effectively keeps injured tissues apart during the critical early stages of healing, offering a promising new tool to prevent the complications of postoperative scarring.
Drowning in papers in your field?
Get daily digests of the most novel papers matching your research keywords — with technical summaries, in your language.