Study On Persistent Luminescent Nanoparticle-based Fluorescence Imaging Technology

Fluorescence molecular imaging technology has been widely applied in the study of biological in vivo imaging with the advantages of non-ionizing radiation,simple imaging process,high imaging time-effectiveness,and low cost.However,there are some problems in fluorescence imaging.When fluorescence imaging is performed,background noise is caused by autofluorescence of biological tissues and the residual of the excitation light signal,which seriously affects signal acquisition and quantitative analysis.Although self-luminous imaging does not interfere with background noise caused by light excitation,self-illumination signals are relatively weak,which will have a certain impact on the quality of bioimaging.In this paper,persistent luminescent materials with longer fluorescence lifetimes and stronger emission intensity are selected to solve the shortcomings of traditional fluorescence imaging and to achieve “excitation-free” bioluminescence imaging.The main contents of this thesis are as follows:First,a fluorescence imaging system for persistent luminescent imaging was designed and constructed.It was developed from the aspects of system design,module selection,data acquisition,and image preprocessing.The system can not only perform persistent luminescent imaging experiments,but also perform transmission-excited fluorescence imaging and bioluminescence imaging experiments.The performance of the system is tested,and by analyzing the total noise model of the imaging system,the sources of noise in the imaging process are explored and corresponding solutions are developed.According to the composition of the system,the application flow of the data acquisition and analysis of the fluorescence imaging system is set,and an optimization scheme that can improve the imaging quality is studied and analyzed for the fluorescence system.Secondly,the particle size and water solubility of persistent luminescent materials are correspondingly improved so that they can meet the requirements of bioimaging,and relevant optical properties are tested and analyzed.Through contrast experiments with Cy5.5,it was found that fluorescence imaging based on persistent luminescent material has higher imaging resolution and signal-to-noise ratio.Dynamic fluorescence imaging experiment based on long afterglow fluorescent materials.The metabolic process was analyzed using a pharmacokinetic model.The results showed that persistent luminescent dynamic fluorescence imaging can quantify metabolic processes.Thirdly,combined with the characteristics of diffusion optical tomography reconstruction technology and persistent luminescent fluorescence imaging,a single angle persistent luminescent fluorescence tomography imaging method was proposed.In order to solve the morbidity of the reconstruction problem,a sparsely constrained regularized orthogonal matching pursuit algorithm is proposed and a good reconstruction effect is obtained.Single-angle persistent luminescent fluorescence tomography,combined with structural images of CT scans,allows three-dimensional distribution of persistent luminescent nanoparticles in mice.The imitative and in vivo experiments show that this method is superior to traditional fluorescence tomography.