Tuesday 14 June 2022

Cell Painting in the Far-Red: DRAQ9

A far-red probe for cell painting and mosaics 

DRAQ9™ is the latest product to come out of BioStatus's R&D.  It's very different from what you're used to seeing from us however, as DRAQ9™ is nuclear-negative yet plasma membrane permeant and famously far-red fluorescing!  

DRAQ9™ labels lipophilic structures in the cytoplasm such as Golgi apparatus, ER, and the vesicular elements of the intracellular vesicular transport system (IVTS) and of the microtubule organising centre (MTOC). 

Essentially, DRAQ9™+ve cells look like doughnuts (aka donuts!) and have a characteristic peri-nuclear "signet-ring" patterning to the staining in the cytoplasm.  If cells are migrating then the pattern has a more directional emphasis, where there appears to be an accumulation of vesicles towards the leading edge of each cell, labelled by DRAQ9™.

DRAQ9™ can also provide a general cytoplasmic stain.  For example, it has been used in development of a method for cytometry of reaction rate constant (CRRC) in motile cells (Yosief et al. 2022), added at 2µM for 30 minutes.

This provides staining of cells, for either live- or fixed- endpoints, that can be the basis of a non-a priori phenotypic screening method since it labels a range of features in the cytoplasm of cells that can be compared to negative and positive controls for features associated with a change in cell biology due to stress, therapeutic or cytotoxic impact or to migration (e.g. scratch-wound assay or spheroid "crashdown").  Cells or populations of cells can then be investigated further in detail for that  observed change or difference.

Helpfully, DRAQ9™ staining is “nuclear-dark” to leave a well-established morphological feature for a nuclear counterstain, if required. The emission spectrum means it is highly compatible with visible-range (e.g. GFP) and UV-excited chromophores.  Importantly, being cell-permeant DRAQ9™ is fully compatible with live end-point measurement of GFP, avoiding the risk of loss of GFP signal associated with fixation.

Practically, DRAQ9™ is provided in an aqueous, ready-to-use solution and can be admixed with formaldehyde fixative for a single-step fix-and-stain procedure.

DRAQ9™ is also suitable for long-term cell tracking due to its low toxicity - see our blog on this topic here

You can find everything about DRAQ9™on the dedicated product page:


Reference:
Yosief, Robel, Giammarco Nebbioso, Vasilij Koshkin, Yumin Qiu, Chun Peng, Vadim Elisseev, and Sergey Krylov. "Making Cytometry of Reaction Rate Constant (CRRC) Applicable to Motile Cells." (2022). Preprint on ChemRxiv, 21 April 2022. DOI:10.26434/chemrxiv-2022-gtgzf

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