Synthesis Of Pd Nanocomposites And Study On Their Photothermal Properties

Recently, nobel metal nanostructures have attracted increasing attention due to their promising applications in optical sensing of biomolecules, optical imaging, and photothermal therapy(PTT). Among these biomedical applications, photothermal therapy on the basis of using near-infrared(NIR) irradiating to produce significant local hyperthermia for destruction of cancer cells has developed very quickly in recent years because it is a noninvasive and harmless approach for cancer therapy. The strong NIR absorption and high photothermal conversion efficiency(η) are keys for photothermal platforms due to the minimal optical absorption of skin and tissue in this region, resulting in the minimum damage. The main issues of practical photothermal nanoplatforms are structure stability and biodegradability. More recently, the Pd nanomaterials have emerged as new kind of promising photothermal agents for cancer therapy due to the strong Localized Surface Plasmon Resonance(LSPR) absorption in the near-infrared region, high photothermal conversion efficiency(η) and excellent photothermal stability. It is shown that the surface-modified with biocompatible polymers on Pd nanomaterials can effectively reduce inorganic nanomaterials toxicity.In addition, loading photosensitizers(PSs) or targeting molecules onto the Pd nanomaterials can further improve therapeutic efficiency and obtain the best treatment effect. Therefore, in this thesis, we synthesize two kinds of Pd nanocomposites and use them as photothermal agents for cancer therapy.(1) Flower-like Pd nanoparticles(NPs) with many small crevices/porous were prepared by using a seed-mediated method in aqueous solutions. Then, biocomatible polypyrrole(PPy) was adopted as package material to coat the flower-like Pd NPs. In comparison to the bare NPs, the prepared PPy coated porous Pd NPs exhibited enhanced NIR absorption and photothermal conversion efficiency, improved structural stability and lower cytotoxicity. In vitro photothermal heating of PPy coated porous Pd NPs in the presence of Hela cell leads to cell destruction after 10 min of laser irradiation at a low power density of 3 W cm-2. The present finding demonstrates that the PPy coated porous Pd NPs are promising potothermal nanoplatform for cancer therapy.(2) Hollow Pd nanoparticles(HPd NPs) with different grain diameters were prepared by one-pot hydrothermal approach. Then, the LSPR of the as-prepared Pd NPs was tuned in order to find the most suitable size of Pd NPs for photothermal therapy. Furthermore, by modifying photosensitizers(Ce6) with polyethylenimine(PEI) and loading the PEI-Ce6 onto the hollow Pd NPs, we finally obtained HPd NPs-PEI-Ce6 nanoomposites. Due to the synergistic effect of Ce6 and HPd NPs functioned as the PDT and PTT agents, the nanocomposites showed improved therapeutic efficiency and obtained great treatment effect in vitro PDT/PTT.