CCK-8 Cell Viability & Cytotoxicity Assay Kit (WST-8)

Overview

At a Glance

A ready-to-use colorimetric assay based on WST-8. In the presence of an electron coupling reagent, mitochondrial dehydrogenases in viable cells reduce WST-8 into an orange-yellow, water-soluble formazan dye. The absorbance at 450 nm is directly proportional to the number of living cells — fast, high-sensitivity cell proliferation and cytotoxicity testing in a standard 96-well plate, with no washing, no cell collection and no solubilization step.

Key Features

• One-tube, ready-to-use: add 10 µL per well, incubate, read — nothing to prepare, nothing to wash
• Superior to MTT / XTT / MTS: WST-8 is more stable and more soluble, with a wider linear range — the formazan product is water-soluble, so no DMSO solubilization step
• Extremely low cytotoxicity: cells typically keep growing after detection, so the same plate can be re-read at multiple time points to locate the optimal measurement window
• Robust in real culture conditions: phenol red and serum show no significant interference — assay directly in regular culture medium
• High-throughput friendly: the entire workflow happens in one 96-well plate, ideal for IC50 / EC50 screening campaigns

Pack Sizes

Enhanced and ultra-sensitive formulations are available for weakly-staining cell types — tell us your cell line and we will match the right format.

Assay Specifications

Protocol (4 Steps)

• 1. Seed: plate cells in a 96-well plate (~2,000 cells/well for proliferation, ~5,000 cells/well for cytotoxicity, 100 µL per well) and apply treatments as required
• 2. Add: add 10 µL CCK-8 reagent per well; include blank wells (medium + reagent, no cells)
• 3. Incubate: 0.5–4 h in the culture incubator
• 4. Read: measure absorbance at 450 nm on a plate reader (confirm no bubbles in wells before reading)

Applications

• Cell proliferation and growth-inhibition assays in drug screening (IC50 / EC50 determination)
• Cytotoxicity testing of anti-cancer compounds and exogenous toxicants
• Cell viability QC after transfection or LNP delivery — pair with our Universal Lipid-Based Transfection Reagent for a complete transfection-plus-viability workflow
• Cytokine-induced proliferation assays; cell therapy (CAR-T / NK) expansion efficiency; organoid drug-sensitivity profiling
• Gene-editing efficiency evaluation and general cell biology research

Handling Notes

• Reducing agents interfere. Antioxidants and other reductants reduce WST-8 independently of cells — remove or account for them, or absorbance will read artificially high.
• Edge-well evaporation: in long cultures the outer wells of a 96-well plate evaporate faster — skip the perimeter wells or fill them with PBS, and check for bubbles before reading.
• Low absorbance? Increase the seeding density or extend the incubation time rather than over-interpreting faint signals.

Research Use Only

For Research Use Only. Not for clinical or diagnostic use.

Ordering & Documentation

Available formats, enhanced / ultra-sensitive versions, COA, MSDS, ISO documentation, FOB pricing, MOQ and lead time are confirmed per inquiry: Send us an inquiry