How does flow cytometry work?

Flow cytometry is a technique widely used in cell biology to detect and measure the physical and chemical characteristics of a cell population. This technique uses a laser as a light source to sort, count and profile cells in a fluid mixture. The process involves injecting a cell sample that is treated with specific fluorescent reagents into a flow cytometer. Depending on the cells being analyzed, the fluorescent reagents used may include DNA binding dyes, fluorescently conjugated antibodies, fluorescent expression proteins, viability dyes or ion indicator dyes. 

The flow cytometer consists of three core systems – fluidics, optics, and electronics. The fluidics system transports the tagged samples from the sample tube past the laser to a flow cell. The optical system consists of excitation light sources, assorted optical filters, and light detectors, which are used to gather and move wavelengths of light around the cytometer and the detection system. The third system is the electronics system or flow cytometer instrumentation, which analyzes cell type based on the difference of wavelength response in the data. 

The flow cytometer allows one cell at a time to flow through the laser beam. The light emits bands of different wavelengths as it scatters through the cell and its components. This allows researchers to quantify up to 3 to 6 properties or components in a single sample, cell by cell, for about 10,000 cells in less than a minute. Its ability to provide a rapid multi-parametric analysis of cells in a solution is one of the key advantages of flow cytometry. 

Flow cytometry is widely used in numerous fields including cancer biology, immunology, virology, infectious disease monitoring, bacteriology, and molecular biology.