After surgery, the human body is often prone to chronic infection, especially in patients with diabetes. How to control bacteria to prevent "making waves" is a medical problem. Recently, the reporter of Science and Technology Daily learned from Nanjing University of Posts and Telecommunications that the team of Professor Wang Lianhui and Associate Professor Yu Wenlihui from Nanjing University of Posts and Telecommunications worked with many scholars to eliminate bacterial infection by reducing the oxygen content in the infected area, regulating bacterial metabolism and ultimately activating drugs. Relevant papers were published in the international academic journal Nature Communication recently. "When bacteria 'cluster', their outer layer will form a layer of extracellular matrix membrane, which is wrapped with many bacteria. This is called biofilm." The first author of this paper, Dr. Xiu Weijun, introduced that bacteria near the surface of the biofilm are sensitive to antibacterial drugs because of their high metabolic activity, while bacteria in the deep layer have a unique defense function against antibacterial drugs because of their low metabolic activity, making ordinary antibiotics unable to play a role, which is easy to cause postoperative infection recurrence and long-term chronic infection. "After applying acne cream, the pimples on my face recur after a while; the foot complications of diabetes patients and the ulcers are difficult to heal after formation are all caused by stubborn bacteria in the deep layer of the biofilm." Xiu Weijun said that in the research on metronidazole, the team found that the treatment effect of metronidazole alone, other common antibiotics, or both was not ideal for stubborn bacteria in the middle and deep layers of biofilm. However, when the team carried out research on photodynamic therapy, it was found that photodynamic therapy could inhibit bacterial metabolism due to the consumption of oxygen, making deep-seated stubborn bacteria more sensitive to metronidazole. In this way, metronidazole can more thoroughly eliminate the stubborn bacteria in the biofilm. In the research, the team constructed a nano reagent composed of hyaluronic acid, photosensitizers dihydroporphyrin and metronidazole, which is used to treat the biofilm infection of methicillin resistant Staphylococcus aureus. The nano reagent can be degraded by enzymes in the biofilm to release dihydroporphyrin and metronidazole. Under light, dihydroporphyrin can convert oxygen into active oxygen, which can kill the active bacteria on the surface of the biofilm, aggravate the anoxic state of the biofilm, and induce methicillin-resistant Staphylococcus aureus to produce nitroreductase, which can convert metronidazole into an imidazole fragment with bactericidal activity, so as to efficiently remove bacteria in the biofilm and inhibit the regeneration of the biofilm. "Dihydroporphin has been used for tumor treatment, and metronidazole is also a commonly used drug, which is a mature therapeutic drug. The targeted drug release performance of hyaluronic acid, a nano material, ensures the safety of target lesions. This new 'nano drug' model of the old drug has not been put into the conversion cycle may be faster than the new drug." Xiu Weijun said. (Outlook New Times)