Annexin V Assays
Find the right Annexin V apoptosis kit
A single 40-minute protocol that separates viable, early-apoptotic, late-apoptotic and necrotic cells. Pair any Annexin V conjugate — FITC, PE, APC, AF647, EV450/500 and more — with a PI, 7-AAD or DAPI viability dye to fit the channels free on your cytometer.
Which Annexin V kit is right for you?
The best kit is the one whose colours fit the lasers and detectors free on your cytometer. Pick the channel you want to read Annexin V in — we'll show the matching conjugates and filter the range below.
The full Annexin V kit range
Filter by the viability dye you want to pair with Annexin V, or search by conjugate or product code.
Why choose these Annexin V kits?
A flexible, panel-friendly way to quantify apoptosis by flow cytometry.
Fast 40-minute protocol
A simple stain-and-read workflow gets you from cells to dot-plot in under an hour.
Dual-parameter clarity
Annexin V plus a viability dye distinguishes early apoptotic, late apoptotic and necrotic cells.
Fits any panel
35 conjugate and dye combinations let you slot apoptosis detection into whatever channel is free.
Adherent or suspension
Validated for cell samples including adherent and suspension cultures.
How the Annexin V assay works
From treated cells to a quantified apoptosis dot-plot in four steps.
Harvest cells
Collect treated and control cells and resuspend in the provided binding buffer.
Stain
Add fluorescent Annexin V and your viability dye (PI, 7-AAD or DAPI); incubate briefly.
Acquire
Run on a flow cytometer, reading Annexin V and the viability dye in separate channels.
Quadrant gate
Resolve viable, early apoptotic, late apoptotic and necrotic populations by quadrant.
The Annexin V assay principle
Annexin V is a calcium-dependent phospholipid-binding protein with high affinity for phosphatidylserine (PS). In healthy cells PS sits on the inner leaflet of the plasma membrane, but early in apoptosis it flips to the outer leaflet — where fluorescently labelled Annexin V can bind and mark the cell.
Pairing Annexin V with a membrane-impermeant viability dye adds a second dimension:
- Viable cells are Annexin V− / dye−
- Early apoptotic cells are Annexin V+ / dye−
- Late apoptotic / necrotic cells are Annexin V+ / dye+
- Analysed by flow cytometry or fluorescence microscopy
Choosing your viability dye
The counterstain distinguishes early from late apoptosis. Pick the one that leaves your Annexin V channel clear.
Propidium iodide
Bright, economical red-emitting dye (ex ~535 / em ~617 nm). Broad spectrum, so keep the far-red/orange channels in mind when building panels.
7-AAD
Far-red emission (~647 nm) with less spectral spillover than PI — a good partner for green or violet Annexin V conjugates.
DAPI
Violet-excited, blue-emitting viability marker that frees up the green, orange and red channels for Annexin V and other panel markers.
Annexin V assay FAQs
What does the Annexin V assay measure?
It measures apoptosis by detecting phosphatidylserine (PS) exposed on the outer plasma membrane of apoptotic cells. Fluorescently labelled Annexin V binds this externalised PS, so apoptotic cells can be quantified by flow cytometry or fluorescence microscopy.
Why pair Annexin V with PI, 7-AAD or DAPI?
Annexin V alone cannot tell early apoptosis from late apoptosis or necrosis, because membrane integrity is lost in later stages. A membrane-impermeant viability dye (PI, 7-AAD or DAPI) enters only cells with compromised membranes, so the two stains together resolve viable, early apoptotic and late apoptotic/necrotic populations.
How do I choose which conjugate to use?
Choose the Annexin V conjugate whose emission fits a detector free on your cytometer and does not clash with your other panel markers. Green (FITC, AF488, EGFP, EV500), violet-blue (EV450), orange (PE), red/far-red (APC, AF647, Cyanine5, PE tandems) and near-IR (PE-Cy7, APC-Cy7, ER780) options are all available.
How long does the assay take?
The staining protocol takes around 40 minutes before acquisition on a flow cytometer.
Can I use these kits with adherent cells?
Yes. The kits are validated for cell samples, including both adherent and suspension cultures; adherent cells are gently detached before staining.
Which quadrant is early apoptosis?
Early apoptotic cells are Annexin V-positive but viability-dye-negative — the lower-right quadrant of an Annexin V (x-axis) versus PI/7-AAD (y-axis) dot-plot.
Not sure which conjugate fits your panel?
Tell our PhD-level technical team your cytometer configuration and existing markers, and we'll help you pick the right Annexin V kit.