Fluorescence Activated Cell Sorting (FACS): An Advanced Cell Sorting Technique

Abstract

Fluorescence-activated cell sorting (FACS) follows the principle of flow cytometry. It is used to separate the molecules or cells of interest from the heterogeneous mixture by selecting the specific cells. The sample is prepared by labelling the cells with fluorescence dye. It is excited by a laser source which results in scattering and fluorescence due to absorbed light. A number of systems have been produced using two or three lasers to excite several dyes. The light scatter and fluorescence detector outputs are amplified and processed for evaluation. The function of fluorescent excitation and detection system is to produce the signals which accurately reflect the amount of each dye associated with the cell. It is applied in the biological research field, i.e. lymphocyte determination, isolation and characterization of infected stem cells, screening of protein binding with various ligands and for the quantification of nucleic acid content in a cell.