1. Where can I order my Spirochrome products?
Spirochrome has appointed dedicated distributors for the SiR-probes: SiR-actin, SiR-tubulin, & cytoskeleton-kit. Customers from North America (US and CA) can order them through Cytoskeleton, Inc. and European customers (without Switzerland) can order them through tebu-bio. For customers outside these regions, the probes can be ordered using these ordering guidelines or by requesting a quote.

Customers from all regions of the world can order the reagents SiR-COOH, SiR-NHS, & Boc-Lys-jasplakinolide, using these ordering guidelines or by requesting a quote.

2. Are the probes stable at room temperature?
Yes, the probes are stable at room temperature for a few days. However it strongly depends on the probe and the solvent. It is recommended to store all the probes or solutions thereof at -20°C.
3. Are SiR-actin and SiR-tubulin toxic to the cells?
Yes, above a certain threshold both probes show some effect on cell proliferation and altered actin or microtubule dynamics. However, the probes are orders of magnitude less toxic that their parent drug. In HeLa cells neither actin nor microtubule dynamics were altered at concentration below 100 nM. At this concentration, Sir-probes efficiently label microtubules and F-actin allowing to record high signal to noise images.
4. After dissolving the probe in DMSO, the solution is colorless, is this normal?
Yes, in DMSO the probe is mainly in the colorless spirolactone form and the color of the solution can vary from colorless to slightly blue. This does not influence the staining efficiency of the probe.
5. Do the probes work on fixed cells?
SiR-actin can be used with PFA fixed cells. SiR-actin labels F-actin in PFA fixed cells as efficiently as Phalloidin-derivatives. SiR-tubulin labels microtubules only in ethyleneglycol-bis-succinimidyl-succinate (EGS) fixed cells. However, a selective labelling of centrosomal microtubules of PFA fixed cells was observed. Sir-actin and SiR-tubulin are not suitable for methanol fixed cells.
6. Is it possible to image live cells with SiR-Probes by STORM?
No, under the very high light intensities typically used in STORM imaging, a phototoxic effect is observd on live-cells.
7. Which organisms and tissues are stained by Sir-probes?
This list is only reporting known working cell lines, tissues or organisms. If a cell line, tissue or organism is not present in the list, it does not mean that it will not be stained by SiR-Probes.

Homo sapiens : U2OS, fibroblasts, HeLa, HUVEC, MCF-10A, HCT-116, A549, erythrocytes.

Mus musculus : C2C12, IA32, skeletal muscle, primary cardiomyocyte, primary oocyte.

Rattus norvegicus : primary hyppocampal neurons, primary cortex neurons, NRK.

Cercopithecus aethiops : COS-7.

Mesocricetus auratus : BHK.

Drosophila melanogaster : Notum epithelium, S2.

Didelphis marsupialis : OK-cells.

Carassius auratus (goldfish) : retina bipolar cells

Danio rerio (zebrafish) : retina bipolar cells

Help us to complete the List by reporting your positive experiences!

8. Do SiR-probes work in 3D cell cultures?
Yes, the probes are able to stain cells in a 3D growth environment.
9. What are the correction factors CF260 and CF280 for SiR fluorophore?
CF260 = 0.116

CF280 = 0.147

10. Why are your prices displayed only in CHF (Swiss Francs)?
Our company is based in Switzerland and therefore our list prices are displayed in CHF (Swiss Francs). Upon request, we will provide you with a binding quote (valid 1 month) based on the displayed CHF prices and the actual exchange rate. Please indicate your preferred currency (USD, EUR, CHF) and payment method (bank transfer OR credit card via PayPal).