Construction of pH-Responsive PDH@AgNPs and Its Application in Wound Healing

Through the oxidative self-polymerization of the 5-HT and DA mixed system and the in-situ generation of AgNPs, pH-responsive PDH@AgNPs were constructed to explore their application in wound healing, providing a more practical basis for the use of AgNPs in this field. PDH@AgNPs were prepared under alkaline conditions, and the nanoparticles were characterized using DLS, TEM and other methods. The effect of different 5-HT:DA monomer ratios on the particle size and zeta potential of PDH-NPs was investigated, and the optimal 5-HT:DA ratio was selected for the preparation of PDH@AgNPs. The antibacterial activities of the formulations were evaluated using in vitro antibacterial assays (E. coli, S. aureus and MRSA). Their biological safety was assessed using in vitro cell proliferation and toxicity experiments. The in vitro antioxidant activity of the PDH@AgNP preparation was evaluated using DPPH free radical scavenging and intracellular ROS scavenging assays. By establishing a skin wound model in C57BL/6 mice and comparing treatment with a free nanosilver wound dressing, the ability of the preparation to promote healing of infected wounds was evaluated. By preparing PDA@Ag and PHT@Ag nanoparticles under different pH conditions, the poor drug release capacity of the PDA materials was addressed. The antibacterial results showed that the PDH@AgNP formulation exhibited good antibacterial properties. The results of the antioxidant, anti-inflammatory and cytotoxicity experiments indicated that the preparation could scavenge free radicals and ROS without toxic side effects on most cells. Changes in the mouse histopathological staining results demonstrated good biological safety. The treatment of infected wounds confirmed their ability to promote wound healing. The prepared pH-responsive PDH@AgNPs provided new ideas and strategies for the clinical treatment of infected wounds.