Artificial spider silk wound dressing helps control infection

When we are injured, skin and soft tissue damage is a very common result, and in some cases, it can pose a major risk to our health and well-being. Therefore, monitoring and promoting wound healing is an important part of the medical response.

Textile dressings are usually used to stop bleeding and protect wounds from infection. However, there is still much room for improvement. For example, the chemical composition of many of these dressings can cause environmental pollution after the material is discarded. In addition, textiles are generally less elastic and therefore not suitable for wounds that require movement, such as wrists, ankles and other joints. Most dressings cannot help doctors and patients monitor the recovery, even if the pH value and inflammatory factors in the fluid secreted by the surrounding tissues during wound healing change during the recovery process, so they can be used as indicators.

Researchers led by Professor Bingfang He from Nanjing University of Technology in China are designing improved textiles to monitor and promote wound healing. The ideal material should have high elasticity, good biocompatibility (that is, it will not cause inflammation or irritation in living tissue) and provide information about wound recovery.

To meet this need, the team developed an artificial spider silk woven textile. Spider silk is the main protein in spider silk and is known for being strong and flexible, and has been used in various biological and industrial environments, for example as a surgical suture.

To create spider proteins, the team used gene fusion technology. The spider gene responsible for the production of arachnoid is added to E. coli. The bacteria will then produce and excrete spider protein, and scientists will collect and purify the spider protein, and then convert it into the final woven textile.

This textile is combined with photonic crystals-this nanostructure affects the movement of photons and is found in iridescent materials such as opals, reflective fabrics and chameleon skin. Adding photonic crystals to textiles causes the dressing to change color according to the pH of the wound drainage fluid, which can be used to indicate the presence of infection.

Gao Bingbing, an associate professor at Nanjing University of Technology and one of the corresponding authors of the study, said that by using photonic crystals, “the wound healing can be directly observed through the color change of the patient or the doctor. [Dressing] will appear different in solutions with different pH values. Color...Bacterial infection can be judged according to the pH value of the wound environment...If the pH is 7-9, the bacteria thrive, doctors can increase the combined use of antibiotics here."

Like other forms of spider silk, this new textile is strong and highly elastic, suitable for moving and bending areas. When used in injured laboratory mice, it also shows good biocompatibility, and when discarded, it quickly degrades into components that are not harmful to the environment.

Another benefit of spider silk fabric is the texture of the material. It contains microscopic channels that can guide wound secretions away from the injured area, while other dressings usually cause secretions to accumulate near the wound.

"Man-made textiles can also be used to prevent or reduce infections," Gao said. "[It] protects the wound from direct contact with the outside world and reduces bacterial infections. At the same time, [it] has high permeability to reduce infections and at the same time ensure oxygen demand during wound recovery."

Now that this new artificial spider silk has been created and proved to be suitable for wound dressings, the next step is to further improve textiles. "In this way, it can truly match the mechanical properties of natural spider silk protein," Gao said. "In addition, we will expand the application of high molecular weight spider silk protein and develop wound textiles with more elasticity, toughness, biocompatibility, and air permeability, especially in the application of artificial skin."

Reference: C. Cheng et al. Programmable woven textiles based on artificial spider silk for efficient wound management, advanced functional materials (2021). DOI: doi.org/10.1002/adfm.202107707