Research On Microfluidic Control Technology And Device For Bioanalysis By Magnetic Beads On Chip

Magnetic beads are diverse,easy to manipulate and widely used,and microfluidic technology is characterized by high throughput,low consumption,portability and automation,etc.Microfluidic systems based on magnetic bead(MB)method have been widely used in bioanalytical fields.However,the current MB-based microfluidic system for bioanalysis still needs to solve some key problems,such as efficient mixing reaction of MBs,fluid manipulation and control during multi-step MB mixing,parallel processing and analysis of multiple samples/multi-indicators,etc.Based on the previous microfluidic technology of parallel threedimensional(3D)mixing of MBs,this project studies the fluid storage-fluid exchange method based on microfluidic chip to realize the parallel 3D mixing of multi-step MBs on the chip and parallel processing and analysis of multiple samples;on this basis,the principle prototype of microfluidic device is constructed and preliminary application validation is carried out.The main research work and related results are as follows:1)For the fluid control of multi-step MB mixing and the parallel processing and analysis of multiple samples/multi-indicators,a single-channel fluid dispensing-fluid exchange microfluidic chip and a multi-channel fluid storage-fluid exchange microfluidic chip were designed,and the effects of chip structure and experimental conditions on fluid control were investigated by fluid simulation analysis,and the feasibility of the multi-channel reservoirexchange microfluidic chip method based on a narrow connection channel structure(with air as the isolation medium and a flow rate of 100 μL/min at the inlet)was confirmed experimentally.2)Combining the parallel 3D mixing technology of MBs proposed in the previous study with the multi-channel liquid storage-liquid exchange microfluidic chip in this study,the principle prototype of bioanalytical microfluidic device based on 3D mixing-automatic liquid change technology of MBs was designed and constructed,and its basic functions(liquid change can be completed within 70s)and feasibility for bioanalysis by MBs were verified.3)The effectiveness of the constructed microfluidic device for cell analysis was verified using the immunomagnetic bead-based CD4+ cell assay,and the HRP-CD3 enzyme-labeled antibody concentration(3.7 ng/m L)and enzyme reaction time(6 min and 12 min)were optimized,and the standard curve was plotted.Subsequently,CD4+ cells were detected using human whole blood samples and compared with the results of flow cytometry,and the feasibility of the microfluidic device for the detection of CD4+ cells in human whole blood was initially verified.The reservoir-exchange method based on multi-channel microfluidic chip proposed in this work can perform reagent storage and fluid automatic control,realize multi-step MB mixing efficiently as well as parallel processing of multiple samples,and can be used to construct a portable bioanalytical microfluidic device based on the principle of multi-step MBs 3D mixing to improve the feasibility and practicality of MB-based multi-sample micro-total analysis system.