PrestoBlue

PrestoBlue is a cell viability reagent used to assess metabolic activity in living cells. It is a resazurin-based dye that changes color and fluorescence in response to cellular metabolism, enabling rapid viability and cytotoxicity assays in cultured mammalian cells, bacteria, and yeast.

The principle is reduction of blue non-fluorescent resazurin by metabolically active cells to pink, fluorescent resorufin. The extent of color change or fluorescence correlates with viable cell number, allowing quantitative readouts with standard plate readers.

PrestoBlue is suitable for high-throughput screening in 96- or 384-well plates and can be used with conventional incubators and plate readers. It is compatible with many cell types and can monitor proliferation, cytotoxicity, and drug responses.

Protocol basics: add a defined working volume of PrestoBlue to wells containing cells in medium, incubate 1–4 hours at standard culture conditions, then measure fluorescence (excitation around 560 nm, emission around 590 nm) or absorbance (approximately 570 nm/600 nm) depending on the instrument and protocol. Signal is generally proportional to viable cell number within a linear range.

Advantages and limitations: PrestoBlue is fast, simple, and less invasive than some assays, allowing real-time or endpoint measurements with minimal handling. Results can be affected by cell type, density, incubation time, reducing compounds, or optical interference, requiring pilot experiments to define optimal conditions.

Storage and safety: Store PrestoBlue according to manufacturer guidelines, typically refrigerated and protected from light. Use before the expiry date and avoid repeated freeze–thaw cycles; handle as a standard laboratory reagent.