Conjugated Polymers-Based Thermal-Responsive Nanoparticles for Controlled Drug Delivery, Tracking, and Synergistic Photodynamic Therapy/Chemotherapy.

Stimuli-responsive multifunctional nanomaterials have attracted much attention due to drug release on-demand for cancer therapy. In this study, the thermal-responsive nanoparticles are prepared based on cationic conjugated poly(fluorene--vinylene) (PFV), temperature-responsive poly(-isopropylacrylamide) (PNIPAM), and antitumor model drug doxorubicin (DOX). Interestingly, the nanoparticles possess multiple functions including thermoresponsive drug release, cell imaging, and chemo- and photodynamic synergistic therapy. The drug is released efficiently above the lower critical solution temperature (LCST) of PNIPAM, and more than 70% of the loaded drugs were delivered at pH 5.5 and 37 °C. Importantly, the drug release process can be tracked by fluorescent imaging owing to the bright fluorescence of conjugated polymer-based nanoparticles. Specifically, conjugated polymer PFV acts as a photosensitizer to produce high reactive oxygen species under white light irradiation, bringing an effective chemo-/photodynamic therapy (PDT) synergistic effect. The cell viability of MCF-7 decreases to only 3.2% after treating with PNIPAM-DOX-CPNs (conjugated polymer nanoparticles) under white irradiation, which is much lower than that with a single treatment. Therefore, the multifunctional nanoparticles provide a promising platform for controllable drug delivery, tracking, and tumor therapy in biomedical applications.