Sequential Growth Of CaF₂:Yb,Er@CaF₂:Gd Nanoparticles For Efficient Magnetic Resonance Angiography And Tumor Diagnosis

Magnetic resonance imaging(MRI)is a highly valuable non-invasive imaging tool by the reason of its excellent tissue penetration,non-ionization radiation and noninvasive.It is the most commonly used diagnostic tool in modern clinical medicine.Contrast agents(CAs)can further improve the sensitivity of magnetic resonance imaging,which can enhance the intensity of signal.In recent years,a great deal of research work has been focused on the design and synthesis of high-performance magnetic nanoparticles based on magnetic resonance contrast agents to improve the quality and specificity of magnetic resonance imaging.The development of nanoscale magnetic resonance imaging contrast agents with high relaxation properties is an important challenge.Gd-based inorganic nanomaterials have the advantages of good longitudinal relaxation,high efficiency and good biosecurity.Based on this feature,in this work,a convenient high-temperature oil-phase method has been used to prepare the sub-10-nm Ca F2:Yb,Er@Ca F2:Gd nanoparticles.The nanoparticles have uniform particle size and stable morphology.The prepared hydrophobic nanoparticles were modified by diblock copolymer PEG-PAA to achieve hydrophilic one.Due to the presence of Gd in the outrmost r fluorinated calcium layer of the nanoparticles,a good longitudinal relaxation rate was observed with a high r1 value of 21.86 m M-1s-1,which is seven times of a commercially available gadopentetate contrast agent(Gd-DTPA).The experimental results show that the hydrophilic Gd-based nanoparticle materials have low cytotoxicity,no hemolysis and no potential gadolinium ion leakage.Under the magnetic resonance scan,the blood vessel detail can be clearly observed to demonstrate good angiographic results.And there was a significant increase in the signal in the 4T1 tumor area after a very low dose of this material was injected.The biocompatibility of a hydrophilic Gd-based nanoparticle was confirmed by a series of biosafety evaluations in vivo in mice as a safe and effective MR imaging of the material Agents and applied to clinical blood pool imaging and tumor diagnosis has made it possible.