Preparation And Properties Of FePt-Au Nanocomposites And The Applications In Cancer Theranostie And Electrocatalysis

Malignant tumor is seriously harmful to people's health,nanomaterials provide a new opportunity to the early diagnosis and specific treatment of the tumor because of their unique magnetic,acoustic,electrical,optical,thermal and mechanical properties.We report the synthesis of multifunctional FePt-Au hybrid nanoparticles(HNPs)via a simple hydrothermal approach and its application in electrochemistry,cancer dual-modality MR/CT imaging diagnosis and simultaneously in-situ therapy.(1)The FePt "seed" was prepared by thermal decomposition reduction method and its preparation conditions was studied,the selection of solvent,reducing agent,stabilizer,the rate of heating and the timing of adding samples would have influence on the morphology of the production of FePt "seed".The FePt-Au HNPs prepared by "seed-mediated" growth method were transferred to the aqueous phase via dimercaptosuccinic acid(DMSA)and then functionally modified by the mercapto polyethylene glycol folic acid(SH-PEG-FA).The morphology and structure of FePt "seeds" and FePt-Au HNPs were characterized by TEM,HRTERM,STEM,UV-Vis and XRD,the results showed that FePt "seeds" and FePt-Au HNPs with face-centered cubic structure(fcc)have uniform size distributions and their particle sizes are ~10 and ~20 nm,respectively.The results of dispersibility test in phosphate buffered saline(PBS,pH ~ 7.38)showed that FePt-Au HNPs after modification of DMSA and SH-PEG-FA on the surfaces exhibited good dispersibility and stability in the aqueous phase.(2)The results of cytotoxicity tests showed that the as-prepared FePt-Au-FA HNPs which integrated active targeting and passive targeting in one exhibited high cytotoxicity to the targeted cancer cells(such as human breast cancer cells(MCF-7),human cervical cancer cells(HeLa)and human hepatoma cells(HepG2))due to the generation of high intracellular reactive oxygen species(ROS)through the Fenton reaction induced by the released Fe within the cells(pH~5.6).However,the results of Fe release test,Prussian blue staining and ROS test showed that the source of cytotoxicity of the FePt-Au HNPs was the excess of intracellular reactive oxygen(ROS)production induced by the Fenton reaction by Fe2+ released by HNPs in the weak acid environment of cancer cells.MR/CT scans in cell and in vivo levels showed that the HNPs were not only useful as a tumor MR imaging contrast agent but also as a CT imaging contrast agent.In vivo anti-tumor and histological studies indicate that the growth of tumor after treating with the HNPs is significantly inhibited with no observable toxicity found in the other tissues.The results showed that FePt-Au HNPs can not only achieve cancer dual-mode MR/CT imaging but also in situ treatment of tumor.Therefore,the FePt-Au-DMSA/PEG-FA HNPs is a promising intelligent and multifunctional nanotheranostic agent for dual-modality MR/CT imaging guided in-situ cancer therapy.(3)We have also studied the applications of FePt-based FePt/C and FePt-Au/C catalysts which have been loaded by the activated carbon(XC-72)and activated under high temperature(600 ?)in the field of electrocatalytic oxygen reduction.The results showed that the initial oxygen reduction potential of the FePt-Au/C catalyst with a body-centered cubic(fct)structure activated at 600 ? is 1.09 V vs.RHE,0.06 V higher than that of the commercial Pt / C catalyst,and almost no change has been found on the polarization curve of the catalysts after 300 cycles of linear voltammetry,indicating that the catalysts have good catalytic oxygen reduction activity and stability.In methanol oxidation,fct-FePt-Au/C catalyst also exhibited higher peak current density than that of Pt/C catalyst(3.05 mA cm-2 vs.2.44 mA cm-2).Therefore,fct-FePt-Au/C catalyst has a good catalytic activity both in fuel cell cathode electrocatalyst and anode electrocatalyst.