Preparation Of Bar-Like Quantum-Dot-Encoded Core-Shell Microparticles On A Microfluidic Chip

At present,the cancer has become a global health problem that human beings are facing.The incidence population has gradually expanded from the elderly to the young,so the early diagnosis of cancer is very urgent.The encoded microparticles provide important carriers for detecting a wide variety of tumor markers at the same time.However,the spectra overlapping phenomenon often occurs in the decoding process of some common fluorescent dye-encoded microparticles,which limits the number of codes.And adding the quantum dots directly to the encoded microparticles usually causes the leakage of quantum dots,making the fluorescence intensity weak and unstable.The core-shell encoded microparticles can effectively avoid the leakage of quantum dots,the fluorescent stability of encoded microparticles can be strengthened,and the mutual interference of different quantum dots can be avoided.In this paper,bar-like quantum-dot-encoded core-shell microparticles were prepared,and cores with different quantum dots in the microparticles could be arranged in order,which involved the position factor and increased the number of codes.The encoded microparticles were labeled by using mixture of food dyes and quantum dots,and light-field images of food dyes and dark-field images of the quantum dots could be respectively observed under a fluorescence inverted microscope raising the number of codes.In the first chapter,the development of microfluidic chip technology,the formation methods of microfluidic droplets,the research status of encoding technology and the preparation methods of encoded microparticles were reviewed.The main encoding strategies,the types of encoded microparticles,and the potential advantages of microfluidic methods in the preparation of encoded microparticles were summarized.Finally the purpose and design idea of this work were proposed.In the second chapter,the experimental device was designed,and the chip configuration,the solutions for preparing microparticles,the influence of flow rates on morphology of encoded microparticles and the factors affecting the number of codes were investigated.The flow-focusing configuration for forming the double phase droplets was selected.The channel changing from narrow to wide contributed to the formation of the double emulsions,and the influence of the channel variation from narrow to wide was discussed.The solutions for preparing core-shell encoded microparticles were tested,and the influences of the flow rates of inner phase,intermediate phase,outer phase on the size and morphology of dual phase droplets were respectively discussed.The core-shell encoded microparticles avoided the problem of the quantum dot leakage and the fusion of core-droplets,and stabilized the fluorescent intensity.In this paper,a new encoding method was proposed,in which factors influencing the number of codes included the number of core-droplets,the position factor,the dark-field images of the quantum dots,the fluorescence intensity,and the light-field images of food dyes.Through experimental verification and theoretical deduction,the formula of calculating the number of codes was proposed.In the third chapter,the research work was summarized,and the applications of core-shell encoded microparticles in biomedical and biological assay were prospected.