Launched just over a year ago, SiR-Actin (Fig 1) and SiR-Tubulin (Fig 2) have been available on the market providing the most convenient tools to stain F-actin and Microtubules in living cells. In the meantime, Spirochrome have launched a third stain based on the SiR-technology – SiR-DNA (Fig 3) to stain DNA in living cells.
These stains meet the central requirements for live cell imaging tools:
- high selectivity
- minimal toxicity
- fluorogenic for wash-free imaging
- applicable in different cell types and tissues
- excited by far-red light
- suitable for super-resolution microscopy
In particular, SiR-Actin and SiR-Tubulin are the only stains available on the market which enable live cell imaging of the major cytoskeletal cellular structures – without the need to transfect cells with vectors carrying the information for fluorescently labeled tubulin or actin or related binding proteins.
The proprietary bright and photostable silicon rhodamine-like (SiR) technology is compatible with most microscopes. It can be used with standard Cy5 settings. The combination of all these properties set SiR-based probes apart from other fluorescent probes. The SiR dyes are coupled to binding components which specifically bind to F-actin (Jasplakinolide natural compound), Microtubules (Docetaxel), or the DNA minor groove binder bisbenzimide (Hoechst).
What do users do with these stains?
Cell biologists work with a number of cell and tissue types and of course every cell types shows some specific characteristics concerning the uptake of tools like our SiR-stains. It is known that the commonly used drug Verapamil which belongs to a group of calcium channel blockers enhances the uptake of SiR-stains in some cell types (for further info, read more here); that is why Verapamil is added to all SiR-stain kits routinely. To give users a good overview which cell types have been already successfully stained with SiR-Actin and SiR-Tubulin, we are building up a data base in cooperation with Spirochrome. Table 1 gives you a quick overview about the data we collected so far from our own and users’ experience. One of the few cells/organisms which could not be successfully stained are fungal cells like yeast or dictyostelium cells. If you are interested in details about the experimental setups used or if you have experience (positive or negative) with other cell or tissue types, we invite you to get in touch by leaving a comment below.
Results recently obtained by SiR-stain users
Fig 1 and 2 show results provided by Erik T. Valent from the VU Medisch Centrum, Amsterdam, The Netherlands (Fig 1) and Bernard M.van den Berg from the LUMC, Leiden, The Netherlands (Fig 2). Both labs stained Human umbilical vein endothelial cells (HUVECs) either with SiR-Actin or with SiR-Tubulin.
Interested in more SiR stain user results in Live Cell Imaging?
More and more results have been published over the past months using the SiR-stains and showing their applicability on miscellaneous cell and tissue samples and in diverse microscopic set-ups.
We’ve compiled a selection of the latest publications using SiR-stains. In this overview you’ll also find first publications with the recently launched SiR-DNA as well as publications in which SiR-derivatives such as SiR-NHS or SiR-tetrazine have been referenced.