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

Abstract

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.