High Pressure Freezing Applications On Life Science

In the last century 30 ’s of Berlin Engineering University of young researcher Ruska developed the first electronic microscope, and in 1986 won the Nobel prize, electronic microscopy of the invention is known as one of the most important inventions in twentieth Century. So human beings from the microscopic world and move forward one step further- the ultra world. The appearance of electronic microscopy has made human’s insight into several hundred times, not only to see the virus, but also to see a number of large molecules,even after a special preparation of certain types of materials in the sample, can also be seen.In ultrathin sections based on, from the 1950 s and negative staining techniques(with a resolution of 2 nm), the three dimensional reconstruction technology in the 1960 s, 1970 s electron crystallography until 1980 s rapid freezing technique(resolution can reach 0.2 nm),in a short period of several decades, electron microscopy made leap in the development, in medicine, biology, materials, geology, archaeology, astronomy etc. has been widely applied in many fields. Along with the development of science and technology, the technology of electron microscope sample preparation has been developed rapidly, and the early stage of the transmission electron microscope is also varied: chemical fixation and physical fixation,including normal temperature and low temperature. Each method has a different application,the subject of these methods to make a comparison, summed up the most appropriate application of each method and some of its improvements. The main research of this subject is the most advanced physical fixed technology, which is the application of high pressure freezing technology. The concept of high pressure freezing technology is the first time Moor Hans and its collaborators were raised at the ETH Zurich in Switzerland in 1968.The aim of this technique is to avoid the unpredictable effects caused by chemical fixation and penetration in the preparation of tissue sections, which makes the sample more close to the life form in the process of ultrastructural analysis. On the application of transmission electron microscope, the ultrastructure of cells, tissues and organs were observed. Although the resolution of transmission electron microscopy(TEM) has reached the atomic level, but in biological sample preparation process, conventional aldehydes and osmium fixed acid,organic reagent gradient dehydration will cause some human disturbance. High pressure freezing technology can effectively avoid these artificial interference. Because in a very short period of time(30ms) can be glass full of 200 m thickness of biological samples, so asto guarantee the fixed samples were very close to the original state. The combination of high pressure freezing technology and frozen substitution, frozen section, frozen section,and combined with other techniques can obtain the most real and true ultrastructure of the sample, and then the most original information in the object of birth is obtained.