Improved photothermal properties of a functionalized polydopamine mediated by chelating iron ions

Because of its good photothermal conversion performance, biocompatibility and adhesion of polydopamine nanoparticles (PDA NPs), PDA has been widely used in the biomedical field. However, its hydrophilicity and stability are not good, and the photothermal properties and absorbance of PDA need to be improved. Functionalized polydopamine nanoparticles (NPDA NPs) were prepared by chelating iron ions to solve this problem. The photothermal conversion capacity and light absorption capacity of NPDA were significantly improved. This was attributed to the catalytic effect of iron ions, which can promote the oxidation reaction of PDA and increase the number of oxygen-containing functional groups. The stability of NPDA was significantly enhanced, which was attributed to the fact that iron ions can form coordination bonds with some phenolic hydroxyl groups in PDA. Additionally, there was no significant difference between the photothermal properties of NPDA and drug-loaded NPDA. Two kinds of drug-loaded NPDA NPs, celecoxib loaded NPDA (NPDA@Cel) and desferrioxamine mesylate loaded NPDA (NPDA@DFO), exhibited drug release properties in slightly acidic environment. Near infrared light promoted drug release of NPDA@Cel. This paper provides new ideas for the biomedical applications of PDA nanomaterials.