Preparation And Properties Of Cuprous Iodide Nano-cluster-based Complexes

X-ray scintillation luminescent material is a luminescent material that can convert high-energy X-ray energy into visible light.Based on the high penetration,differential absorption,photosensitivity and fluorescence of X-rays,X-ray scintillation materials are widely used in radiation monitoring,luggage security inspection,non-destructive testing,space exploration and medical diagnosis.Photodynamic therapy(PDT)has attracted widespread attention in tumor therapy.However,the visible light used in PDT has a relatively shallow penetration depth in the tissue,resulting in poor treatment effects for tumors in deep tissues.X-ray stimulated photodynamic therapy(PDT)is a great concept in oncological treatment especially in deep-seated tumor PDT.However,there are still challenges to be overcome such as containing heavy metals or toxic elements,bulk crystals or rigorous preparation.Therefore,the development of X-ray excited materials with high luminous efficiency and no heavy metal elements will broaden the potential applications of X-ray scintillators in the biological field.This thesis aims to develop new scintillation luminescent materials and construct composite nanoparticles with X-ray stimulated photodynamic effects.The specific research contents are as follows:(1)In order to solve the problems of heavy metal elements contained in scintillation luminescent materials,and the complicated and harsh preparation process,this part of the work uses cuprous iodide and pyridine as raw materials,and obtains a series of cuprous iodide cluster-based complexes by adjusting the reaction and crystallization conditions.In order to explore the luminescence mechanism and the structure-activity relationship of the material,this work mainly regulates the structure of the inner core(cuprous iodide cluster)of the complex by adjusting the preparation and crystallization conditions of the material.At the same time,the complex is adjusted by the adjustment of the solvent.The stacking state of molecules and the distance between molecules and the study of its crystal structure and photophysical properties.In this system,the cuprous iodide cluster-based complex has charge transfer light emission between nuclear cluster atoms and charge transfer light emission between halogens and ligands.X-ray single crystal diffraction results show that the core structure of the obtained series of cuprous iodide cluster-based complexes includes cubane,trapezoid and rhombus structures.Fluorescence spectroscopy results under X-ray excitation show that the cubane-type structure and rhombus have luminescence under ultraviolet and X-ray irradiation,which is attributed to the charge transfer luminescence between the nuclear cluster atoms and the charge transfer luminescence between the halogen and the ligand trapezoid.The complexs with“Chair-like”cluster exhibits the emission of blue light under ultraviolet and X-ray irradiation,which is attributed to the charge transfer between the halogen and the ligand.In addition,the emission wavelength of the cubane structure changes with the change of the molecular packing state.In short,in this system,we have obtained four kinds of cuprous iodide with high luminous efficiency under X-ray irradiation.In addition,the crystal structure and photophysical properties,the structure-activity relationship and luminescence mechanism are summarized,which further broadens the types of X-ray scintillation luminescent materials.(2)In order to solve the problem of large size of scintillation materials which can not be applied to biological imaging and tumor therapy,in this work,cuprous iodide copper cluster complex Cu₄I₄py₄,which has excellent luminescent properties under X-ray irradiation,has been synthesized by precipitation and microemulsion method to obtain a series of nanoparticles with different morphologies.The experimental results show that the coordination bond between pyridine and cuprous iodide cluster will be affected by the group of surfactant,resulting in dissociation and loss of luminescent properties.Finally,Cu₄I₄py₄ nanoparticles with high dispersion and luminescent properties in water were prepared by coating the surfactant polyvinylpyrrolidone,but the particles are not stable in physiological environment.Finally,the Cu₄I₄py₄@polystyrene nanoparticles with good stability in biological systems were obtained.After loading with the photosensitizer(methylene blue),the hybirid nanoparticles exhibit the ability to generate reactive oxygen species under X-ray excitation.Scanning,transmission electron microscopy and photodynamic properties show that by adjusting the concentration ratio of polystyrene in microemulsion reaction,the size of the composite nanoparticles can be controlled to 100-200 nm.By adjusting the concentration ratio of Cu₄I₄py₄ and photosensitizer,singlet oxygen can be generated under the irradiation of X-rays.In conclusion,in this system,Cu₄I₄py₄ nanoparticles with different morphologies and functions were prepared by precipitation method and microemulsion method.In particular,the composite nanoparticles were coated by polystyrene and reloaded with photosensitizers by microemulsion method.They can not only be stable in various biochemical environments,but also generate singlet oxygen under the irradiation of X-rays.It is expected to solve the problem of tissue penetration depth in tumor photodynamic therapy.