Bandage against bleeding and infection
The dressing releases several medications
ChemPort.Ru based on Chemical & Engineering News: Bandage Releases Multiple Drugs Over TimeIn the case of a gunshot wound or other injury, it is necessary to take measures very quickly both to stop bleeding and to prevent infection.
Researchers have developed a "smart dressing material" of double action, which over time will be able to save lives, immediately solving both problems.
Paula T. Hammond, a chemical technology specialist from the Massachusetts Institute of Technology and her colleagues have been developing drug-releasing dressings for several years.
Previously, researchers used the method of layer-by-layer assembly to produce films of micrometer or even nanometer thickness capable of releasing a drug for a certain time. By irrigation or spraying, they injected an aqueous solution containing a medicinal product into a gelatin sponge. This active layer alternated with a solution of another active molecule, which was glued to the first layer due to the difference in charges or some other complementary property. Earlier, the Hammond group had already obtained films that released the blood clotting drug thrombin, which, in animal tests, demonstrated the ability to stop bleeding. Another film was able to secrete the antibiotic vancomycin for a long time.
Despite the success in creating materials that release individual drugs, the creation of dressings capable of releasing several drugs at once was not an easy task. If the thrombotic agent and the antibiotic are released at the same rate, the release of thrombin may be too slow for effective blood clotting, and the antibiotic may be too fast to achieve effective protection against infection.
Based on the results of previous work, the researchers wanted to create a dressing material that can secrete both drugs at the right time and at the right speed. However, they knew that the conditions used to make the thrombin-containing coating could damage the vancomycin-releasing film. Eventually, they managed to find a way to stabilize the coating containing the antibiotic by covalently binding vancomycin to poly(beta-L-lactic acid) (PMLA). The vancomycin-PMLA film remains stable if it is coated with thrombin, and the binding of PMLA to vancomycin does not affect the antimicrobial properties of the latter.
At the next stage, the researchers tested the properties of gelatin sponges containing thrombin and the vancomycin-PMLA aggregate. When the substrate polymers are dissolved in the film, most of the thrombin is released immediately, within a few minutes. Vancomycin bound to polylactic acid is then released at a slower rate, being completely released within a few days. In vitro tests, thrombin released from the dressing material interacts with other blood factors, forming blood clots. Tests of the activity of the antibiotic released from the dressing material showed that it suppresses Staphylococcus aureus with the same effectiveness as the control sample of vancomycin.
The dressing material based on gelatin sponge quickly releases thrombin, stopping bleeding (red dots). Then, within a few hours, he secretes vancomycin (blue dots) to prevent infection of the wound. The remaining polymer materials holding the films together (blue and green lines) also dissolve.
(Figure from the article by Hsu et al. Multifunctional Self-Assembled Films for Rapid Hemostat and Sustained Anti-infectious Delivery // ACS Biomater. Sci. Eng., 2015 – VM).Hasan B. Alam, a specialist in disaster medicine from the University of Michigan, notes that the new dressings seem promising, but require additional research – to prove the usefulness of new dressings, it is necessary to test them on experimental animals.
Hammond says that her group is currently conducting in vivo research, and also expresses interest in creating other types of dressings that release various combinations of drugs – painkillers or drugs that promote accelerated wound healing.
Portal "Eternal youth" http://vechnayamolodost.ru17.03.2015