A technique for quickly measuring the biological properties of individual cells or organelles in a fluid flow system, and classifying and collecting specific cells or organelles from a population. It is characterized by quantitative determination of cell DNA content, cell volume, protein content, enzyme activity, cell membrane receptors, and surface antigens through rapid determination of Coulter resistance, fluorescence, light scattering, and light absorption. Based on these parameters, cells of different properties are separated to obtain pure cell populations for biological and medical research. The current maximum sorting speed has reached 30,000 cells per second. Brief History In 1934, A. Mordawan reported for the first time an automatic cell counting method for passing suspended red blood cells through a glass capillary placed on a microscope stage. In 1956, WH Coulter introduced a device that uses cell resistance in a conductive solution through a small hole (75 to 100 microns) between two small chambers (called Coulter resistance) to count cells and measure cell volume. . In 1965, LA Kamensky made a multi-parameter flow cytometer that can measure cell size and nucleic acid content. In the same year, MJ Fuller made a cell sorter. In 1969, Van Dyll et al. Used argon ion laser and layered shell flow technology to establish a flow cytometer in which the liquid flow, illumination optical axis and detector axis are orthogonal to each other. Later, the cell sorting meter improved by HR Hewlett et al. Can make the cells in the flowing liquid spray into the air for measurement. However, in each of the above systems, the laser beam used and the restricted aperture in the detection direction of collected fluorescence are larger than the cells in the flow, so they cannot provide information about cell morphology, so they are called zero resolution. system. Subsequently, LL Wheelis and SF Patten developed a low-resolution slit scanning technique that can measure nuclear fluorescence, cell and cell nucleus size. In 1969, W. Gede and W. Dietrich described a flow cytophotometer that uses a mercury lamp as a light source. Under epi-illumination, it can excite cells flowing parallel to the optical axis in the flow chamber.
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2. die
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4. no
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Principle The sample to be tested (such as cells, chromosomes, sperm or bacteria, etc.) is stained with a fluorescent dye to make a sample suspension. The nozzle of the flow chamber is ejected to become a flow of cell fluid and intersects the incident laser beam. The cells are excited to produce fluorescence, which is collected by an optical system placed at 90 ° to the incident laser beam and cell fluid. The blocking filter in the optical system is used to block the excitation light; the dichroic beam splitter and other blocking filters are used to select the fluorescence wavelength. The fluorescence detector is a photomultiplier tube. The scattered light detector is a photodiode used to collect forward scattered light. The small angle forward scattering is related to the size of the cell (Figure 1).
