Study And Development Of A Large Volume PCR Temperature Control System For Automated Aptamer Screening

Nucleic acid aptamers are increasingly used in the field of the disease diagnosis and treatment with characteristics of the high affinity and high specificity.Cell-SELEX is a live cell-based in vitro selection method,which utilizes differences in the protein or the structure of different cell surfaces to effectively select aptamers that can bind specifically with target cells.However,a series of complicated operations and a long selection period are needed to achieve high-specificity aptamers selection by manual methods,which cannot meet the actual demand for aptamer selection technologies.The automatic Cell-SELEX aptamer selection method is of great significance for acting as the substitute for the manual operation process and improving the selection efficiency within a shorter selection period.To this end,our group is developing an automated machine based on a fully enclosed cartridge for the Cell-SELEX.In this thesis,a special PCR reaction chamber with the volume of 400 μL for the automated nucleic acid aptamer selection is developed,which greatly simplifies the selection process and effectively avoids the cross-contamination that may occur during the transfer of samples in manual selection experiments.The research is focused on the design of the system structure,hardware,software and temperature control strategy.In the end,the experimental verification and performance test are carried out to prove the feasibility of the system.The dual-channel temperature control strategy combined with the fuzzy self-adaptive PID algorithm is used after comparing the actual control effect of different control methods.The result shows that the temperature control system can meet the performance requirements of the PCR temperature control for the automated aptamer selection machine with the heating rate up to 5.68 ℃/s,the cooling rate up to 2.04 ℃/s and the steady-state control accuracy within 0.2 ℃.Combining closely with the need of the development of the automated aptamer selection machine,the temperature control of the PCR has been studied in detail in this thesis.The dualchannel temperature control strategy combined with the adaptive fuzzy PID controller is designed for this system with the great temperature delay,which can adjust the output in time according to the temperature relationship between the heat sink temperature and the PCR mixture temperature.Meanwhile,it greatly simplifies the manual parameter adjustment process and ensures the temperature control accuracy of the system,making the system very versatile at the same time.