The Annexin V-YSFluor™ 488/PI Apoptosis Detection Kit utilizes Annexin V conjugated to YSFluor™ 488 as a fluorescent probe to detect early-stage apoptosis. The assay can be analyzed by flow cytometry or other fluorescence detection platforms.

Principle of Detection:In healthy, viable cells, phosphatidylserine (PS) is localized to the inner leaflet of the plasma membrane. During early apoptosis, PS is translocated to the outer surface of the cell membrane, becoming exposed to the extracellular environment. Annexin V is a 35–36 kDa Ca²⁺-dependent phospholipid-binding protein with high affinity for PS. Fluorescently labeled Annexin V-YSFluor™ 488 binds specifically to PS exposed on the surface of early apoptotic cells.

This kit also includes Propidium Iodide (PI), a nucleic acid dye used to distinguish early apoptotic cells from late apoptotic or necrotic cells. PI is membrane-impermeant and cannot enter live or early apoptotic cells with intact membranes. However, it readily penetrates cells with compromised membranes—such as late apoptotic or necrotic cells—and stains their nuclei red.

When used together: Viable cells: Annexin V⁻ / PI⁻; Early apoptotic cells: Annexin V⁺ / PI⁻; Late apoptotic or necrotic cells: Annexin V⁺ / PI⁺ (dual-positive).

Features

Rapid and reliable detection: Enables fast and accurate discrimination between live, early apoptotic, late apoptotic, and necrotic cells.

Dual-color staining: Combines Annexin V-YSFluor™ 488 for early apoptosis (green) and propidium iodide (PI) for late apoptosis or necrosis (red).

High sensitivity and low background: Provides clear, distinct population separation in flow cytometry or fluorescence microscopy.

Wide compatibility: Applicable to both adherent and suspension cells from various mammalian species.

Simple protocol: One-step staining procedure without cell fixation, preserving cell morphology and viability.

Components