Research On Membrane-based Microfluidic System For Processing Biomaterial Cryoprotectant Agents

With the wide application of biosamples such as germ cells,stem cells and immune cells in the field of clinical disease treatment and scientific research.Cryopreservation faces more and more micro-volume biosamples,and the existing techniques or methods are not ideal.System efficiency needs to be significantly improved to meet actual demands.The solution is processed through these devices in a single pass,and it is difficult to sufficiently load/unload the cryoprotectant agents.Based on the spontaneous “concentration-dilution” effect,a new membrane-based microfluidic system was developed to efficiently and safely load/unload cryoprotectant agents for micro-volume biosamples.For the proposed method,the main research work is as follows:1.Chip and system design: Based on the principles of fluid dynamics and orthogonal experimental design,the micro-channel related geometric parameters were simulated and optimized,and the optimal microfluidic chip design was obtained.Then,motion structure system and limit system of the multi-channel syringe pump were designed in detail.The integration of the whole prototype was completed by establishing a control platform based on STM32 development board,and useing Keil uVision5 software to compile control program.Finally,the running speed and flow accuracy test of the syringe pump were carried out.The results show that the accuracy of prototype is over 97%,which is meeting experimental requirements and can be applied to cryoprotectant agents loading/unloading experiment.2.Study on the mass transfer characteristics of membrane-based microfluidic system: A theoretical model of fluid flow and transmembrane mass transfer was established.The effects of different mass transfer parameters on the concentration of cryoprotectant agents and the dynamic change of cell volume were simulated and analyzed,and the optimal treatment conditions were obtained.The accuracy of the theoretical model was validated by carrying out cell-free experiment.The analysis shows that the theoretical calculation data is in good agreement with the experimental results.The experimental study on the concentration distribution and output characteristics of the solution further indicates that the system can process the cryoprotectant agents in a controlled and efficient manner.3.Experimental study on the treatment of red blood cells cryoprotectant agents: After theoretical and cell-free research experiments,the basic characteristics of system mass transfer were mastered,and a series of cell experiments were carried out to further analyze the actual performance of the system.The experimental results show that the system can load cryoprotectant agents for 50 ml red blood cells suspension in about 8min.The concentration of red blood cell suspension solution changes continuously and the final cell recovery rate reaches 93.78%.The above research results show that the proposed membrane-based microfluidic system can effectively realize the smooth and controllable loading/unloading of cryoprotectant agents for micro-volume biosamples,and it is expected to greatly improve the efficiency and effect of cryoprotectant agents treatment of micro-volume biological samples.