Construction And Application Of Fe@Fe₃O₄ Nanomaterials With Enhanced Magnetic And Photothermal Properties

Cancer has become one of the most lethal diseases in the world,and it is the biggest killer of human health.It is urgent to find a cure for cancer.Magnetic therapy and photothermal therapy are newly developed tumor thermal ablation techniques.Magnetic therapy uses magnetic nanoparticles（MNP）to convert magnetic field energy into thermal energy through Néel-Brownian relaxation under a high-frequency alternating magnetic field（AMF）,and increases the local temperature of the lesion site to induce cell death.It has lots of advantages such as non-invasive,non-invasive,remote control,etc.Photothermal therapy uses photothermal conversion reagents to convert the light energy of near-infrared（NIR）light into thermal energy,thereby killing cancer cells at high temperatures.It has the characteristics of non-invasiveness,high selectivity,and accurate positioning.The development of both technologies depends on the development of corresponding reagents.Fe@Fe₃O₄ magnetic nanomaterials not only have both photothermal and magnetocaloric properties,they can also be used as MRI contrast agents.Therefore,it is a diagnostic and therapeutic integrated material with clinical application prospects.However,the properties of the currently prepared Fe@Fe₃O₄ magnetic nanomaterials still need to be further optimized.Based on this,we explored the construction strategies of Fe@Fe₃O₄ magnetic nanomaterials with enhanced magnetic and photothermal properties,and studied their application in cancer diagnosis and treatment.The application is as follows:First,Fe@Fe₃O₄ nanoparticles were loaded into RAW246.7 macrophages by phagocytosis of macrophages.The obtained Fe@Fe₃O₄@RAW has better magnetic thermal performance and T2-weighted MRI contrast performance.Then,using the hypoxia predisposition of macrophages,Fe@Fe₃O₄@RAW was injected into tumor mouse models to carry out image-mediated magnetocaloric therapy.In vivo experiments prove that macrophages can transport the loaded material to the tumor hypoxic area well,use its aggregation effect to better heat,and improve the treatment effect on the tumor hypoxic area.Second,the influence of oxidation time on the magnetic properties during the preparation of Fe@Fe₃O₄ nanoparticles was explored to synthesize high-performance Fe@Fe₃O₄ nanoparticles.Experiments show that when the oxidation time is set to 100 minutes,its saturation magnetization（Ms）is the highest,and its magnetic and thermal performance is also the best.At the same time,different surface ligands were used to modify them,and the results showed that the ligands had little effect on the heating efficiency of the nanoparticles.Third,construct targeted Fe@Fe₃O₄ nanoparticles to improve tumor enrichment.Coupling polyethylene glycol（PEG）,nuclear targeting ligand（NLS）and membrane targeting ligand（RGD）to the surface of Fe@Fe₃O₄ nanoparticles modified by dopamine acrylamide（Dop-Ac）through click chemistry,This enables the material to target the nucleus of a tumor cell and generate heat from inside the cell,thereby killing cancer cells faster and more efficiently.