Studies On Multiplexed Fluorescence Detection System For Microfluidic Chips

With the rapid development of life science,more and more researchers focus on the study of the molecules relevant to biomedicine.It is of great significance to develop the fast and simple methods for simultaneously detecting multiple biological molecules.Due to the huge number of biological molecules,special and flexible multiplex detection techniques need developing.So far,the multiplex technology based on fluorescence encoding has been greatly improved in high throughput detection of multiple targets.Microfluidics features small consumption of sample,fast mass transfer,high analysis speed and easy integration of functional components,which is an ideal platform for multiplex detection with high throughput.Hence,we would develop a multiplexed fluorescence detection system for microfluidic chips to measure different target molecules based on multiple color fluorescence.It would provide a powerful tool for simultaneous detection of multiple biological molecules.In chapter 1,the conventional microfluidic optical detection techniques were reviewed firstly,which include absorbance detection,chemiluminescence detection and fluorescence detection.Then,the advantages and limits of detection methods mentioned above were summarized respectively.Finally,the purpose and the design of this work were proposedIn chapter 2,the multiplexed fluorescence detection system for microfluidic chips was built based on laser-induced fluorescence principle.A laser emitting a line-patterned beam was used as the excitation light source to excite multiple targets at the same time.The orthogonal light path was designed to reduce the interference caused by the exciting light.The multiplexed fluorescence detection system consisted of several photomultiplier tubes,optical fibers and optical filters.Using the microfluidic chips with different channel structures,the analytes were measured under different flow conditions to demonstrate the performances of multiplexed fluorescence detection system.The limits of detection of Rhodamine 6G were 2.0×10-9 mol/L,1.5×10-10 mol/L and 6.2×10-9 mol/L in the continuous flows for the triple-detector system,and 4.7×10-9 mol/L and 7.2×10-9 mol/L in the droplets for the double-detector system.The results showed consistency among multiple fluorescence detection units.Using the microfluidic chips generating double-color droplets,the droplets respectively containing Rhodamine 6G and quantum dots(excitation wavelength 625 nm)were formed in the same microchannel and tested by the multiplexed fluorescence detection system.The limits of detection were 2.9×10-9 mol/L for rhodamine 6G and 7.4×10-11 mol/L for quantum dots.It was demonstrated that the multiplexed fluorescence detection system was feasible for multiple target determination on microfluidic chips.In chapter 3,the multiplexed fluorescence detection system for microfluidic chips was summarized,and its prospective applications in biological analysis were discussed.