Dynamically United Double Network Structure Based on Polydopamine to Enhance pH‐Sensitive Seaweed‐Based Film for Medicine

Abstract The drug‐loaded and seaweed‐based composite film with high mechanical properties was prepared based on the dynamically united calcium alginate/carboxymethyl chitosan (CA/CMCS) double network structure with the help of polydopamine (PDA). The enhancement mechanism could be attributed to three aspects. Firstly, a dynamic cross‐linking network formed by Schiff base reaction between CMCS and oxidized starch (OXS). Secondly, sodium alginate (SA) and CaCl 2 formed an ion cross‐linking network. Finally, PDA and CMCS underwent the Michael addition reaction to form dynamic covalent bonds that dynamically combined the two networks. The effect of CMCS content on wettability and mechanical properties of the composite film was explored in order to improve the comprehensive properties used in the medical field. The drug‐loaded film containing ciprofloxacin inclusion compound had excellent slow‐release performance and pH sensitivity. It had obvious antibacterial properties against Escherichia coli and Staphylococcus aureus , and the excellent cell growth rate. It has broad prospects as a wound dressing to treat bacterial infections and smart drug delivery, and is expected to be applied in the field of biomedicine.