Zinc oxide/Polydopamine@PNIPAm core-shell phase change nanocomposite for samrt NIR-responsive drug delivery systems

In order to solve the global environmental pollution and energy shortage problems and to improve energy efficiency, thermal energy storage technology has received increasing attention in recent years. In this research, a composite phase change material with a core-shell structure was successfully synthesized using zinc oxide (ZnO) nanoparticles as the core, self-polymerized polydopamine (PDA) as the photothermal conversion medium and free-radical polymerized poly-N-isopropylacrylamide (PNIPAm) hydrogel phase change material as the shell. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and thermogravimetric analysis (TG) were used to characterize and analysis the ZnO/PDA@PNIPAm (ZPP) phase change nanocomposite. The photothermal conversion experiments show that the ZPP core-shell composite phase change material can raise the temperature of 0.5 mL pure water by more than 10 °C under 0.1 W/cm2 NIR light irradiation for 1000 s, and the photothermal efficiency was ∼25%, which had excellent photothermal conversion capability. Interestingly, this photothermally induced structural change was successfully used for Imidacloprid (IMI) release and could be controlled by NIR light. The results of four kinetic model fittings demonstrated its diffusion release behavior. Therefore, the ZPP core-shell phase change nanocomposites can be used as a smart NIR-responsive system for drug release.