Controllable Preparation Of Small Size Near Red Persistent Luminescent Nanoparticles

In all kinds of biological imaging probes,optical probes can track or detect the cellular activities in the organism,so as to achieve early disease diagnosis and later monitoring treatment effect.Different from other imaging probes,fluorescence-based optical probes have the advantages of simple operation and high sensitivity.The application of traditional optical probes in biological field still has some disadvantages,such as unstable luminescence caused by self-fluorescence,low tissue penetration,high biological toxicity and low signal-to-noise ratio,which greatly limits the application of traditional fluorescent materials in biological imaging field.Probes based on near infrared(NIR)persistent luminescent nanoparticles(PLNPs)have attracted considerable attention in the field of biological imaging because this type of probes has excellent characteristics of high optical and chemical stability,deep tissue penetration and no biological background luminescence.In addition,combination of the long persistent luminescent nanoparticles,with other contrast agents could achieve multimodal imaging with high resolution and sensitivity in disease diagnosis,subsequent treatment and monitoring process,which allows us to obtain more accurate and reliable results.However,the size,luminescence properties and biocompatibility of PLNPs need to be further improved.Although NIR-PLNPs can be widely used in the field of biological imaging,it is still a great challenge to synthesize luminescent nanoparticles with controllable size,biosuitability,high luminous intensity and long afterglow time.To overcome these problems,Size controllable near infrared-emitting Zn Ga₂O₄:Cr³⁺,In³⁺(ZGO:Cr,In)persistent luminescent nanoparticles(PLNPs)were prepared via a facile one-step hydrothermal method.The nanoparticles possess good water dispersibility and nanosize distribution(6?28 nm).The size and persistent luminescence properties of ZGO:Cr,In PLNPs depended on co-doping amounts of In³⁺.The results showed that when the doping amount of In³⁺was 0.2%,the average particle size of ZGO:Cr,In PLNPs was the smallest(13.79 nm),and the NIR luminescence was the strongest.The afterglow time was estimated for 5 d,and can be re-excited by LED lamp.ZGO:Cr,In PLNPs were pure spinel structure,and the doping of In³⁺did not affect the crystal structure of PLNPs.To enrich the variety of PLNPs,respectively co-doped Pr³⁺,Li⁺,by one-step hydrothermal generation,prepared a series of Cr³⁺single doped Zn_1.4Ga_2(1-x)O₄:x Cr(ZGO:x Cr,x=0%,0.05%,0.25%,0.45%,0.65%,0.85%)PLNPs,the effect of Cr³⁺on the luminescence intensity of ZGO:x Cr PLNPs was investigated,and the doping amount of Cr³⁺was optimized;Co-doping Pr³⁺and Li⁺at the optimal Cr³⁺doping concentration,Co-doped Pr³⁺and Li⁺were obtained at optimal Cr³⁺doping concentrations to obtain small sizes of NIR-emitting Zn_1.4Ga_2(1-x-y)O₄:x Cr,y Pr(ZGO:x Cr,y Pr,x is the optimal Cr³⁺doped concentration,y=0%,0.05%,0.10%,0.15%,0.20%,0.25%)PLNPs,Zn_1.4Ga_2(1-x-y)O₄:x Cr,y Li(ZGO:x Cr,y Li,x is the optimal Cr³⁺doped concentration,y=0%,0.05%,0.15%,0.25%,0.35%)PLNPs,the effects of Pr³⁺and Li⁺doping on ZGO:x Cr,y Pr PLNPs,ZGO:x Cr,y Li PLNPs size,persistent luminescence property and crystal structure were investigated,respectively.The results show that the optimal Cr doped concentration is 0.25%;Pr³⁺,and Li⁺can improve the afterglow luminescence performance and improve the quantum yield;the introduction of Pr³⁺enables the size of PLNPs to be adjustable,and the co-doping of In³⁺has the conclusion of acquaintance,The results showed that when the doping amount of Pr³⁺was 0.15%,the average particle size of ZGO:Cr,Pr PLNPs was the smallest(8.56 nm);The introduction of Li⁺has no effect on the size of PLNPs,and the synthesized PLNPs are all pure phase spinel structure.