Preparation And Application Of Gadolinium-based Rare Earth Composites With Multi-functional Core-shell Structure

With the development of science and technology,highly efficient and multifunctional nanomaterials have been widely used in the diagnosis and treatment of tumors.Composite nanomaterials are the most effective synthetic materials,which can combine imaging diagnosis and treatment to achieve the purpose of killing cancer cells.In this work,Prussian blue(PB)and polydopamine(PDA)used as photothermal materials are combined with gadolinium-based materials with imaging properties through different core-shell structures to realize the integrated applications of imaging diagnosis and chemical-photothermal therapy.The specific works are as follows:(1)PB@Gd(OH)CO₃ nanoparticles with yolk-shell structure were synthesized via a facile sacrificial template method.The nanoparticles were consisted of PB as core,Gd(OH)CO₃ as shell.The hollow interior between the core and shell was formed by using SiO₂ as the sacrificial template.PB@Gd(OH)CO₃ nanoparticles present high drug loading capacity owing to the special yolk-shell structure(0.94 mg DOX/mg nanoparticles)and p H/NIR dual-responsive release properties.Due to the existence of Gd³⁺,PB@Gd(OH)CO₃ nanoparticles can serve as T₁-weighted MR imaging contrast agents.In addition,the prepared nanoparticles also exhibit good biocompatibility and high photothermal conversion efficiency(31.8%).In vitro experiments show that the synergistic treatment combing with photothermal therapy and chemotherapy can effectively improve the efficacy of treatment and reduce the viability of tumor cells.(2)Hollow gadolinium oxide nanoparticles(Gd₂O₃)were first synthesized using SiO₂ as a sacrificial template.Then polyacrylic acid(PAA)served as a nanoreactor and template to fabricate Gd₂O₃@PAA@PDA core-shell nanoparticles.Since Gd is a rare earth paramagnetic metal ion,PDA has excellent photothermal conversion ability,the nanoparticles can be used for MR imaging and photothermal therapy.The nanoparticles were further modified with cyclodextrin(CD)to obtain CD-modified Gd₂O₃@PAA@PDA nanoparticles,which can be used to load the hydrophobic drug hydroxycamptothecin(HCPT).The results show that the photothermal conversion efficiency?of this nanoparticle can reach to 37.8%,the load capacity is about 0.92mg HCPT/mg nanoparticles,and the drug can be released faster under the dual response of p H and NIR.In vitro experiments proved that the nanoparticles have good biocompatibility,and the synergistic treatment of chemo-photothermal therapy can obtain the best therapeutic effect.