ATTO 488

Flow cytometry (FC) is a technique for high-speed, step-by-step quantitative analysis and sorting of single cells or other biological particles in a suspension by detecting labeled fluorescent signals.

Flow cytometric DNA-content cell-cycle staining measures the fluorescence intensity of DNA-bound fluorochromes in single cells or nuclei to estimate DNA content distributions, allowing assignment of populations to G0/G1, S, and G2/M phases by DNA histogram deconvolution. Propidium iodide (PI) intercalates into DNA, and PI fluorescence is proportional to cellular DNA content when staining is performed under conditions that make DNA accessible and minimize non-DNA signal. Cells with G2/M DNA content are expected to show approximately twice the fluorescence intensity of G0/G1 cells, while S-phase cells occupy intermediate fluorescence values. PI-based DNA-content analysis can also detect cells with fractional DNA content, often reported as sub-G1, when DNA fragmentation and extraction during staining reduce retained DNA signal in apoptotic cells. DAPI is an alternative DNA fluorochrome for univariate DNA-content analysis, while bivariate approaches combining DNA content with proliferation

Fluorescence in situ hybridization detects specific DNA or RNA sequences inside fixed cells or tissue sections by hybridizing fluorescently labeled nucleic-acid probes to complementary target sequences, allowing the target’s copy number, chromosomal position, spatial distribution, or transcript abundance to be visualized microscopically. DNA-FISH detects genomic loci, chromosomal gains/losses, amplifications, deletions, and rearrangements, while RNA-FISH detects RNA molecules or transcript localization; in cancer cells, mouse tumors, neurons, organoids, macrophages, or drug-screening samples, the readout is fluorescent puncta, fusion/split signals, or localized RNA signal interpreted relative to validated controls.

Phospho-flow cytometry detects intracellular phosphorylated signaling proteins in single cells using phospho-specific antibodies after rapid fixation and permeabilization; the fluorescence intensity reflects phosphorylation state and therefore kinase-pathway activation, inhibition, or drug response in defined cell subsets. Unlike Western blot, phospho-flow preserves single-cell resolution and can measure signaling heterogeneity in cancer cells, primary immune cells, dissociated mouse tumors, macrophages, organoid-derived cells, and drug-screening samples when validated antibodies and fixation/permeabilization conditions are used.

Fluorescence activated cell sorting (FACS) is a special technology for identifying and separating rare cell populations with high purity.

The labeled nucleic acid probe is hybridized with the DNA or RNA on tissues and cells by using the complementary base sequence between the single strands of nucleic acid molecules. The detected DNA or RNA molecules in situ in cells can be displayed by autoradiography, fluorescence detection or enzyme color development.

Fluorescence-Activated Cell Sorting (FACS) separates cells in suspension after flow-cytometric measurement of light scatter and fluorescence; classic droplet-based instruments interrogate cells with a laser, convert optical signals into electronic signals, charge droplets containing target cells, and electrostatically deflect them into collection vessels. FACS detects phenotypes defined by fluorescent antibodies, fluorescent proteins, viability dyes, or intracellular markers, and the readout is the sorted fraction, purity, recovery, and post-sort viability of the gated population.