A polypeptide micelle template method to prepare polydopamine composite nanoparticles for synergistic photothermal–chemotherapy

Motivated by the wide interest in natural melanin and biomimetic polydopamine (PDA) in biomedical applications, the easy self-polymerization of dopamine (DA) under mild conditions, and the strong adhesive ability of PDA on various surfaces/interfaces, we for the first time develop a polypeptide micelle template method to fabricate PDA-coated composite nanoparticles and their anticancer drug doxorubicin (DOX)-loaded ones. After continuous-wave diode laser irradiation of the nanocomposite solution (5 min, 808 nm, 2 W cm−2), the magnitude of temperature elevation increased over the concentration of DA and the reaction time, respectively, and the nanocomposite solution was heated by 33.4 °C compared to the 4.2 °C increase for the PBS buffer. As evaluated by flow cytometry, and fluorescence microscopy, AO/EB double staining technique, and standard MTT assay, the DOX-loaded nanocomposites entered into HeLa cells and killed them efficiently. They gave a half maximal inhibitory concentration (IC50) of 30.5 μg mL−1 and a combination index of 0.59, which exhibits a good synergistic antitumor effect for the combination photothermal–chemotherapy. By utilizing the core-cross-linked polypeptide micelles as a soft template, this work provides a facile strategy for the fabrication of biocompatible PDA–polymer nanocomposites, which hold promise for the synergistic photothermal–chemotherapy of cancer.