How to choose the best cytotoxicity assay for your experiments
Cytotoxicity assays assess the degree to which a compound or treatment induces cell damage or death. Our cytotoxicity assays allow you to determine whether cells remain viable after exposure to specific conditions, so are essential when screening drugs, assessing toxicology, and investigating a disease’s mechanism of action.
This guide will simplify the selection process and help you find the right assays for your experiments.
What do you need to consider when choosing a cytotoxicity assay?
Cytotoxicity assays use various methods to assess cell damage and death. Assays tend to measure cell membrane integrity, using
- Enzyme leakage
- Membrane-impermeable dyes
- Amine-reactive dyes
Explore below to learn about these methods and find the right assay for your research.
How do I directly measure cell membrane damage?
Enzyme leakage assays assess cell membrane damage directly by quantifying the activity of enzymes like lactate dehydrogenase that leak into the extracellular medium.
How our enzyme leakage assays can help
Our range of enzyme leakage assays includes the ever-popular lactate dehydrogenase (LDH) assay, which provides a simple and reliable method for quantifying the release of cytotoxic molecules from various cell types in low numbers, including over time. Our assays come in various formats (eg colorimetric and fluorometric) and sensitivities for easy workflow integration. Our assays are also compatible with other cellular assays to enhance your experiments further.
LDH Assay Kit (Cytotoxicity)
- Simple, no-wash assay with one 30-minute, room-temperature incubation step
- Colorimetric readout at 450 nm
LDH-Cytotoxicity Assay Kit (Fluorometric)
- Sensitive, quick and easy way to detect released LDH levels
- Fluorometric readout (Ex/Em 535/587 nm)
- Suitable for plate reader
How do I use membrane-impermeable dyes to measure cytotoxicity?
Cell viability assays often use membrane-impermeable fluorescent dyes (mostly DNA stains) that stain cells with damaged cell membranes. Propidium iodide has largely been replaced by DRAQ7™ and 7-AAD for cell viability assays due to its broad emission spectra and tendency to bind to live cells.
How our dyes can help
Our membrane-impermeable dyes are compatible with many fluorescence-based experimental and workflow applications, including flow cytometry and immunofluorescence microscopy. Our dyes can be combined based on spectral emission profiles for deeper phenotyping.
DRAQ7™
- Selectively stains the nuclei of dead and permeabilized cells
- Can be used in combination with common labels like GFP and FITC
- Ex/Em 633 & 647/665-800 nm
- Suitable for flow cytometer and microscope
7-AAD Staining Solution
- Ready-to-use nucleic acid dye solution
- Ex/Em 488/647 nm
- Suitable for flow cytometer and microscope
Propidium Iodide
- Stains double-stranded DNA
- Ex/m 536/617 nm
- Suitable for flow cytometer and microscope
How do I use amine-reactive dyes to distinguish live and dead cells?
Amine-reactive dyes weakly stain viable cells by binding to cell surface amines and strongly stain membrane-compromised cells by reacting with intracellular amines. Dead and live cells can be differentiated by fluorescence level.
We’ve combined multiple dyes into live:dead cell assays to make the selection process even easier.
How our dyes can help
Amine dyes are particularly useful in functional studies to differentiate live and dead cells, and are compatible with fixation methods.
Live and Dead Cell Assay
- Differentially labels live and dead cells using two fluorescent dyes (ethidium homodimer and esterase-cleaved dye)
- Simple one-step protocol
- Suitable for flow cytometer and fluorescence microscope
What other cytotoxicity assays are available?
Alternative cytotoxicity assays evaluate protein content in fixed cells to determine the extent of cytotoxicity.
SRB Assay / Sulforhodamine B Assay Kit
- Binds stoichiometrically to proteins in adherent cells under mild acidic conditions and is extracted under basic conditions
- The amount of SRB extracted is proportional to cell mass
- Colorimetric readout at 565 nm
Crystal violet Assay Kit (Cell viability)
- Stains cells that are attached to cell culture plates; cells detach from cell culture plates upon death and are washed away
- Colorimetric readout at 570 nm
