Advances in Apoptosis Detection: Annexin V-FITC/PI Double Staining with AffiSTAIN

The Annexin V-FITC/PI double staining apoptosis detection kit, marketed under the name AffiSTAIN, represents a significant advancement in the field of apoptosis research. This kit offers researchers a robust and reliable method for detecting apoptosis in cultured cells through flow cytometry analysis. This article provides a comprehensive overview of the technical principles underlying the AffiSTAIN kit, its advantages, and its applications in apoptosis research.

Apoptosis, or programmed cell death, plays a crucial role in various physiological processes, including development, tissue homeostasis, and immune response. Dysregulation of apoptosis is implicated in numerous diseases, including cancer, autoimmune disorders, and neurodegenerative diseases. Therefore, accurate detection of apoptotic cells is essential for understanding the underlying mechanisms of disease and developing therapeutic interventions.

Principle of Annexin V-FITC/PI Double Staining

The Annexin V-FITC/PI double staining assay is based on the differential binding of Annexin V and propidium iodide (PI) to apoptotic and necrotic cells, respectively. Annexin V is a calcium-dependent phospholipid-binding protein with a high affinity for phosphatidylserine (PS), a lipid typically located on the inner leaflet of the plasma membrane in healthy cells. During apoptosis, PS is translocated to the outer leaflet of the plasma membrane, where it becomes accessible to Annexin V binding.

In the AffiSTAIN kit, cells are first incubated with Annexin V conjugated to fluorescein isothiocyanate (FITC), which emits green fluorescence upon excitation. FITC-labeled Annexin V binds specifically to exposed PS on the surface of apoptotic cells, allowing their identification by flow cytometry.

Simultaneously, cells are stained with PI, a DNA-binding dye that is impermeable to intact plasma membranes but can penetrate the membranes of necrotic and late-stage apoptotic cells. PI binds to DNA and emits red fluorescence upon intercalation, enabling the discrimination of necrotic and late-stage apoptotic cells from viable and early apoptotic cells.

Advantages of AffiSTAIN

The AffiSTAIN kit offers several advantages over traditional apoptosis detection methods:

High Sensitivity

The combination of Annexin V-FITC and PI staining allows for the detection of both early and late-stage apoptotic cells, providing a comprehensive assessment of apoptosis.


AffiSTAIN can be used with a wide range of cell types and experimental conditions, making it suitable for various research applications.

Quantitative Analysis

Flow cytometry enables quantitative measurement of apoptotic cell populations, allowing for precise determination of apoptotic rates and kinetics.

Multiplexing Capabilities

AffiSTAIN can be combined with other fluorophores or antibodies for multiplexed analysis of apoptosis and other cellular processes.


The AffiSTAIN kit has been widely used in apoptosis research and drug discovery. Some common applications include:

  • Evaluation of drug-induced apoptosis in cancer cell lines.
  • Assessment of apoptosis in response to environmental stressors or pathological conditions.
  • Monitoring apoptosis during cell differentiation and development.
  • Screening for potential apoptosis-modulating agents.

The Annexin V-FITC/PI double staining apoptosis detection kit AffiSTAIN represents a valuable tool for researchers studying apoptosis and related cellular processes. Its high sensitivity, versatility, and quantitative capabilities make it indispensable for both basic research and drug development efforts aimed at targeting apoptosis-associated diseases. By providing a comprehensive understanding of apoptotic mechanisms, AffiSTAIN contributes to advancements in biomedical science and the development of novel therapeutics.

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