Construction And Application Of Microfluidic Chips Based On Embedded Obstacle Passive Micromixer

The microfluidic chip(lab on a chip)integrates or basically integrates basic operation units such as sample preparation,reaction,separation,detection,and cell culture,sorting,and cleavage involved in the fields of chemistry and biology into a few square centimeters or even Smaller chips,a network of microchannels,with a controllable fluid throughout the system to replace a variety of functions in conventional chemical or biological laboratories[1].The microfluidic chip has small linear scale,high physical quantity gradient,large specific surface area,precise fluid flow control and good optical performance.We will select the separation / enrichment of circulating tumor cells(CTCs)in whole blood samples and the dissolution of oral solid micro-nano preparations,design and optimize the structure of the chip based on the previous research,and develope two microfluidic chips based on embedded obstacle passive micromixer to stablish a fast,accurate and miniaturized technology platform for the separation / enrichment of CTCs and dissolution detection of oral solid micro-nano preparations.Method:1.Study on the performance of arrayed CTCs-chips and anti-tumor drug sensitivity test.(a)Design and manufacture arrayed CTCs-chips,and surface modification and antibody immobilization to increase the chip's capture efficiency of CTCs.(b)Carry out the separation detection methodand method validation study on the CTCs-chip using whole blood samples and human lung adenocarcinoma H1975 cells to establish an efficient CTCs separation detection method.(c)Blood samples from 30 clinical tumor patients and 20 normal subjects were collected and the capture rate of CTCs was measured using the integration advantages of CTCs-chip.(d)The anti-tumor drug sensitivity test was carried out on the chip with the captured tumor cells and the structural characteristics of the CTCs-chip.2.Structural design and optimization of drug dissolution chip: structural design of drug dissolution chip(DDC)by MEMS software,calculation and simulation of liquid flowin chip by ANSYS finite element analysis software,By investigating the flow velocity,manifold,shear force,etc.of the chip,Optimized the configuration of the cavity and micro-dam,micro-dam density and micro-dam angle.And provide a new method for the dissolution detection of oral solid micro-nano preparations.3.Study on the performance of drug dissolution chip.(a)Establish an HPLC method to determine the ibuprofen content refer to the USP42 and verify it.(b)Optimize the injection flow rate using ibuprofen oral suspension,to establish a drug dissolution chip for oral solid micro-nano preparation dissolution visual monitoring and concentration analysis method.(d)The dissolution test of ibuprofen oral suspension was carried out on the chip under the optimal conditions,and determines the applicability and accuracy of the method by comparing with the paddle method.Results:1.An arrayed CTCs-chip with a "displaced herringbone" ridge and four independent microchannels was designed and fabricated.The chip was surface modified,antibody immobilized,and flow rate optimized.At an injection flow rate of 20?L/min and a rinsing flow rate of 60?L/min,H1975 was specifically captured in the whole blood sample,and an average cell capture rate of 87.02% and an average capture purity of 99.58% were obtained.The method has high specificity,repeatability and accuracy,and can detect whole blood samples with H1975 cell density as low as 5 cells/mL,It can be used for clinical sample detection and achieved a detection rate of 76.67%(23/30).In the drug screening test,the difference in the killing effect of the five drugs on tumor cells was qualitatively shown.2.Through the comparative analysis of the fluid simulation results of ANSYS software,the optimal configuration of the drug dissolution chip was determined.The cavity of the chip consists of two circular arcs of different sizes.The cavity is 200 ?m deep and the volume is 80 ?L.There are 140 independent herringbone symmetrical micro-dams with a height of 100?m arranged in the cavity,the micro-dam angle is 140°,and the arm length is500?m.There is a gap of about 2mm between the micro-dams.The chip has strong turbulence and interception effect,can mix the dissolution medium and separate /immobilize the solid particles of the micro-nano preparation efficiently,and can simulate the dissolution of the oral solid micro-nano preparation in the human body accurately..3.HPLC method was used to establish the determination method of ibuprofen content.The method has good linearity,stability,precision and recovery rate,and can be used for accurate determination of ibuprofen content in the eluate.At the optimized injection flow rate of 70?L/min,the chip method can accurately measure the dissolution rate of the ibuprofen suspension by comparison with the dissolution test results of the paddle with ibuprofen oral suspension.The crystal changes are monitored in real time,and the effect of the pH of the dissolution medium on the dissolution of the drug can be sensitively reacted.Conclusions:In this paper,two microfluidic chips based on embedded obstacle passive micro-mixer were developed,which established a fast,accurate and miniaturized technology platform for the separation/enrichment of circulating tumor cells in whole blood samples and the dissolution detection of oral solid micro-nano preparations.