Synergistic antimicrobial Cur-PEI-Mn3O4 for wound sterilization and accelerated healing

To overcome the problem of poor water solubility of curcumin used for antibacterial purposes and the limitation that a single treatment method is difficult to achieve the expected therapeutic effect for drug-resistant bacteria, this study has developed a new type of composite material, Cur-PEI-Mn 3 O 4 (MPC). During the preparation of the composite material, the water solubility of curcumin (Cur) has been enhanced by modifying it with polyethyleneimine (PEI), and it has been combined with Mn 3 O 4 nanocylinders to improve the therapeutic effect. The experiment has proved that MPC can catalyze the production of reactive oxygen species (∙OH) from H 2 O 2 under slightly acidic conditions and consume glutathione (GSH). While in neutral conditions, when the concentration of MPC is 160 μg mL −1 , the clearance rate of ∙O 2 − can reach 80 %. The in vitro antibacterial experiments have shown that 1 mg/mL MPC + H 2 O 2 could significantly inhibit methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli (with a survival rate of 20 %). The mechanism includes damaging the bacterial membrane structure, causing protein leakage, depleting GSH and generating ∙OH. In the MRSA-infected wound model, MPC, under the acidic microenvironment of the wound in the early stage, can catalyze the production of ∙OH from H 2 O 2 and consume GSH to destroy the bacterial biofilm. In the neutral environment during the later stage of wound healing, MPC can exert antioxidant effects, significantly promoting epithelial regeneration (increased expression of Masson and CD31, decreased expression of IL-6 and TNF-α), and accelerating wound healing. Therefore, the improved solubility component Cur in this complex, along with the Mn 3 O 4 component with multiple catalytic activities, can work together to resist drug-resistant bacteria and thereby heal wounds infected by MRSA.