Design And Performance Research Of Hydrophilic Persistent Luminescence Nanoparticles

With the rapid development of the economy,emerging technologies and multi-discipline fusion applications have put forward higher challenges and expectations for the development of materials.In recent years,biological windows persistent luminescence nanoparticles(PLNPs)are widely used in optical imaging and early disease diagnosis in the field of biomedicine due to their unique excitation-emission process separation,high sensitivity,and high signal-to-noise ratio.Biomarkers,cancer cell identification,disease diagnosis and other functions require materials to be efficient,accurate,and sensitive,which means that PLNPs need to have good biocompatibility.The hydrophilicity of the material is directly related to its biocompatibility.At present,the mainstream PLNPs are all inorganic nanoparticles.Due to the hydrophobic properties of their passivated surfaces,they are easy to aggregate and settle in water environments,and have very poor dispersion.This is not conducive to the flow and penetration of PLNPs in organisms,indicating that their biocompatibility is poor.Now most researches focus on the synthesis and design of PLNPs,mainly considering the afterglow intensity,decay time and morphology,but ignoring the problem of its hydrophilicity in organisms.Therefore,in view of the above-mentioned problems,the research and exploration of hydrophilic PLNPs has important practical significance.This thesis is divided into five chapters,dedicated to exploring new ideas and new methods for designing and synthesizing hydrophilic PLNPs from three major directions:new material systems,synthesis methods,and surface modification.The first chapter describes the development history,afterglow mechanism and models,research significance and existing problems of long persistent materials,and briefly summarizes the research content and significance of this thesis.The second chapter introduces the commonly used preparation methods,preparation materials,instruments and characterization methods of PLNPs.The third,fourth and fifth chapters discuss the main research content and results of this topic.The specific research results are as follows:(1)This thesis introduces a conventional precipitation method.The precursor is obtained by chemical precipitation and then heat-treated.During the heat-treatment,even if the particles have experienced relatively high temperatures,they still maintain a small size.In the third chapter,SrAl₁₂O₁₉:Cr³⁺near-infrared PLNPs were successfully synthesized.Compared with the solid-state method,this synthesis method effectively reduces the heat treatment temperature,saves energy,and reduces the requirements for equipment and production costs.In Chapter 4,a Fe³⁺-doped SrAl₁₂O₁₉ near-infrared PLNPs was designed and synthesized by the conventional precipitation method.The obtained SrAl₁₂O₁₉:Fe³⁺shows bright afterglow in the range of 750 nm to 1000 nm,and the afterglow duration at 810 nm is longer than 90minutes.(2)In order to improve the surface hydrophilicity,3-aminopropyl triethoxysilane(APTES)was used as a surface modifier to improve the passivation surface of SrAl₁₂O₁₉:Cr³⁺and SrAl₁₂O₁₉:Fe³⁺PLNPs.After encapsulating SrAl₁₂O₁₉:Cr³⁺and SrAl₁₂O₁₉:Fe³⁺with APTES,SrAl₁₂O₁₉:Cr³⁺@APTES and SrAl₁₂O₁₉:Fe³⁺@APTES nanocomposites showed hydrophilic stability for more than 7 days and 20 days in aqueous solution,respectively.(3)In Chapter 5,designed and synthesized soluble Eu³⁺,Tm³⁺doped CaO red light long persistent materials.CaO:Eu³⁺,Tm³⁺was synthesized by solid-state method.The sample has multiple luminescence peaks in the red to near-infrared range,including 595 nm,616 nm,658nm,710 nm,and 823 nm,corresponding to ⁵D₀?⁷F₁,⁵D₀?⁷F₂,⁵D₀?⁷F₃,³F_3,2?³H₆,³H₄?³H₆ transitions,and the afterglow duration at 595 nm is longer than 3600 s.CaO:Eu³⁺,Tm³⁺react with water to form Ca(OH)₂ which is slightly soluble in water,and the afterglow intensity gradually weakens as the reaction progresses.The material can achieve the effect of degradation by reacting with water and the product is dissolved in water in a large amount of water environment of organisms,and has a wide range of applications in drug delivery and disease treatment.