Design Of Scheme On Realization And Detection Of Nucleic Acid Amplification In Deep Space Life Exploration

Looking for extraterrestrial life is always a topic of concern in deep space exploration. The question of existence of extraterrestrial life is being payed close attention by more and more people, with the development of science and the further explorations. Deep space life exploration embodies significant value of research on life's origin, development and evolution.Targeting at exploration of lower life forms in deep space, polymerase chain reaction (PCR for short) and fluorescently marked detection were chosen as methods of nucleic acid amplification and its result's detection respectively, after comparison of several schemes. Combining of these two methods could achieve nucleic acid amplification and detection with minimum process, thus introduction of pollution and interference was avoided. The preparation and marking of amplification samples, which were completed by the project's partner Institutue of Microbiology, Chinese Academy of Sciences, did not belong to this research content.Focused on external conditions of PCR and fluorescence detection, a scheme to achieve the goal of nucleic acid amplification and detection was designed. The scheme consisted of amplification chamber, reactor, detection unit, mode switch unit, control unit and data acquisition monitoring unit.Amplification chamber, which provided temperature circulation needed for PCR, was in time-domain form. Its parameters were determined through modeling and simulation utilizing ANSYS ICEPAK software. Detection unit was designed with LED being excitation light source and CCD camera being detection device. Detection optical path, which efficiency was given a simplified calculation, was constructed using optical fiber, lenses and filters. Three different reactors were made by PDMS, PC and glass which were of the properties of good biological compatibility, low self fluorescence and transparent. These reactors were used to bottle biological samples. Manufacture process to make reactors was explored and improved. Mode switch unit was designed by stepping motor and photoelectric switch. It achieved function to switch modes between amplification and detection. Data acquisition monitoring unit was developed on platform of LabVIEW and Visual C++ 6.0. It has realized functions of setting amplification parameters, monitoring reaction status, real time data sampling and display, real time image sampling and display, correspondence test. Every unit in this system could realise its function through module testing. The whole system, after the preliminary integration, could realize functions of nucleic acid amplification and detection by experimentation, which provided the proof that scheme designed in the paper was feasible and successful.