Cell Health

Cell viability refers to the number of healthy cells in a population and can be evaluated using assays that measure enzyme activity, cell membrane integrity, ATP production, and other indicators. These methods can employ luminescent, fluorescent, or colorimetric readouts as indicators of general cell viability or even specific cellular pathways. Cytotoxicity and cell viability assays are often used to assess a drug or other treatment’s effect, and are valuable tools in the search for new therapeutics, as well as advancing our understanding of how normal cells function.

Cell Viability, Cell Proliferation, Cytotoxicity Assays (MTT, XTT, MTS)

Colorimetric assays using tetrazolium salts like MTT, XTT, and MTS can be used to measure cell proliferation and cytotoxicity. For example, the MTT assay depends on the reduction of MTT by enzymes present in viable cells to form a blue formazan product that can be quantified by measuring the absorbance. The choice of assay may be based on the desired workflow and time required.

DNA/RNA Quantitation

The absorbance of a DNA sample measured at 260 nm on a spectrophotometer or microplate reader can be used to calculate its concentration. Absorbance quantitation of DNA works on samples ranging from about 0.25 µg/mL to about 125 µg/mL in a microplate format.

Drug Discovery & Development

For every drug that makes it to the finish line, another nine don’t succeed. This alarming failure rate can be traced to reliance on 2D cell cultures that don’t closely mimic complex human biology, often leading to inaccurate predictions of a drug’s potential and extended drug development timelines.

ELISA

Enzyme-linked immunosorbent assays (ELISAs) are used to measure the amount of a specific protein, using a microplate format, and results are most often detected via absorbance in the visible wavelength range. Chemiluminescent and fluorescent ELISA formats offer enhanced sensitivity for accurate quantitation of less abundant analytes.

Endotoxin assays

Monitoring for contaminants is a critical step during the production process in the pharmaceutical and medical device industries. A frequent contaminant, endotoxin, can cause fever, inflammation, headache, nausea, and even death. Fortunately, endotoxins can be readily monitored using turbidimetric, colorimetric, or fluorometric assays.

Enzyme kinetics, bacterial / microbial growth

Many biological experiments require monitoring bacterial growth or measuring enzymatic changes over long periods of time (hours, days or even weeks).

Micro-volume Applications

Quantitation of many sample types is accomplished through absorbance measurements in a cuvette or microplate. However, when material is scarce or samples are precious, quantitation of very low sample volumes is required. Instruments and accessories are available that enable quantitation in volumes as low as 2 µL, or even 0.5 µL.

Microbiology and Contaminant

Microbes, including bacteria, have been estimated to make up about 15 percent of the earth’s biomass, and microbes in the human body outnumber human cells by 10 to 1. These microorganisms provide great benefit to us and are also vital to many fields of research from medicine to alternative energy production. On the other hand, monitoring for microbes and the toxic substances they produce is necessary to ensure the safety of pharmaceutical products. Scientists whose research relies on mammalian cells must carefully monitor these cultures for unwanted microbial contaminants to ensure that their experimental results are reliable.