Development Of A Rapid Gel Electrophoresis And Real-Time Imaging System

Gel electrophoresis is a technique for the separation of molecules based on their physical properties.Moreover,it is easy to operate and with low cost,and thus it is widely applied in the separation of nucleic acids and proteins.However,the traditional gel electrophoresis system is time consuming,large reagent consumption,required ultraviolet light source is harmful to the body,off-line imaging system is needed.In order to overcome those drawbacks,we developed an on-line fast electrophoresis system in this work.Such a system can effectively reduce the time consumption and regent volume.The visible light used is harmless to the body.This thesis consisted the following three parts of the self-built electrophoresis system: the mechanical part,the circuit control part,and the software developed for the system.The mechanical part mainly includes the device parts and the SGE chip,wherein the SGE chip is the core part of the gel electrophoresis,and the three-dimensional size of the chip lane is summarized by series of experiments.Results showed that DNA fragments with different lengths can be separated by this chip.The circuit control system mainly includes the single-end flyback isolated switching power supply and corresponding drive circuit.According to the electrophoresis experimental requirements,the control voltage range of single-end flyback isolated switching power supply is 0.5-10.5 V.The output power is 25 W.The output voltage ranges from 12 V to 250 V.The ripple of output voltage is less than 350 mV,and the output voltage can be increased step by step and with 1 V of step length.Overshoot voltage does not exceed 5 V when high voltage is generated.The driving circuit mainly introduces the STM32F103RBT6 chip.The main function of this chip is connected with the PC and send the command of the voltage value to the lower-computer in the form of ASCII code.The lower-computer processes it through the drive chip,and generates the control voltage matching the output voltage in the circuit,and then outputs the same voltage with the PC through the switch power supply.Meanwhile,the drive chip can get the output voltage and transmit the signal to the PC in real time,so that the parameters can be set on the lower-computer at the PC.The software part mainly depicts how to monitor the electrophoresis process in real time by SGE software,and how to identify and analyze the results of gel electrophoresis.This software can control the start and end of the lower-computer through serial communication,set electrophoresis voltage and time,collect image information in real time and finally present the image on the PC.In addition,the results of gel electrophoresis were analyzed by Canny contour detection algorithm and local adaptive threshold binarization algorithm for fragments recognition,Hof transform line detection and clustering analysis are for analysis of what bands belong to the same lane.Besides,the relative migration distance of each band is tabulated into a table.Through the table,we can analyze the data in the software by linear fitting,and thus we can know the size of the unknown DNA.