I2633 Sigma-Aldrich


polymethine dye

Synonym: Foxgreen, IC Green, Indocyanine green

  • CAS Number 3599-32-4

  • Empirical Formula (Hill Notation) C43H47N2NaO6S2

  • Molecular Weight 774.96

  •  Beilstein Registry Number 4115884

  •  EC Number 222-751-5

  •  MDL number MFCD00013078

  •  PubChem Substance ID 24895979



Related Categories C, Cell Biology, Core Bioreagents, Hematology and Histology, Research Essentials,
form   powder
composition   Dye content, ~90%
solubility   H2O: 1 mg/mL


General description

Cardiogreen is a negatively charged polymethine dye that forms noncovalent fluorescent complexes with proteins. This "pseudofluorogenic" property has been utilized for protein determination by capillary electrophoresis with diode laser-induced fluorescence detection.


25, 50, 100 mg in glass bottle

Bottomless glass bottle. Contents are inside inserted fused cone.


Cardiogreen has been used to resolve several labeled proteins including: human serum albumin, ribonuclease A, transferrin, and cytochrome c.
Cardiogreen has been used as an intraocular capsular stain. It has been used in the dye-dilution method for cardiac output.

Safety & Documentation

Safety Information

GHS07  GHS07
Signal word 
Hazard statements 
Precautionary statements 
Personal Protective Equipment 
NONH for all modes of transport
WGK Germany 

Frequently Asked Questions

How does the storage temperature relate to shipping conditions?
The storage conditions that a Sigma-Aldrich catalog and label recommend for products are deliberately conservative. For many products, long-term storage at low temperatures will increase the time during which they are expected to remain in specification and therefore are labeled accordingly. Where short-term storage, shipping time frame, or exposure to conditions other than those recommended for long-term storage will not affect product quality, Sigma-Aldrich will ship at ambient temperature. The products sensitive to short-term exposure to conditions other than their recommended long-term storage are shipped on wet or dry ice. Ambient temperature shipping helps to control shipping costs for our customers. At any time, our customers can request wet- or dry-ice shipment, but the special handling is at customer expense if our product history indicates that the product is stable for regular shipment. See Shipping and Storage for more information.
Which document(s) contains shelf-life or expiration date information for a given product?
If available for a given product, the recommended re-test date or the expiration date can be found on the Certificate of Analysis.
How do I get lot-specific information or a Certificate of Analysis?
The lot specific COA document can be found by entering the lot number above under the "Documents" section.
How do I find price and availability?
There are several ways to find pricing and availability for our products.Once you log onto our website, you will find the price and availability displayed on the product detail page.You can contact any of our Customer Sales and Service offices to receive a quote. USA customers: 1-800-325-3010 orview local office numbers.
What is the Department of Transportation shipping information for this product?
Transportation information can be found in Section 14 of the product's (M)SDS.To access the shipping information for this material, use the link on the product detail page for the product.
Has Cardiogreen been used for in vivo optical imaging studies?
We do not subject this product to in vivo testing. However, one study documents the use of the product in a study with mice:For optical imaging, mice were injected intravenously with a mixture of 0.05 ml of 260 μM ICG (Cardiogreen) and 0.05 ml of 360 μM DTR (70,000 MW, Invitrogen) in saline (equivalent to 0.4 mg per kg or 7.4 μM initial concentration in blood).
Does Cardiogreen dissolve equally well in saline and in water?
Each lot is tested for solubility in hot water at 1 mg/mL. We have found that Sigma Product No. I2633 (which has the same CAS number as Product No. 21980) dissolves in water at 1 mg/mL without heating. Further dilute in saline to prepare an isotonic solution.
How long can I store a solution of Cardiogreen after it has been prepared?
Sigma-Aldrich recommends that solutions be prepared fresh and not stored. Solutions "are stable only for a few hours and cannot be kept overnight." See: Sigma-Aldrich Handbook of Dyes, Stains, and Indicators, Green, F. ed., p. 407.
Can Product No. I2633, Cardiogreen, be used as a biological stain?
Limited absorbance in the visible region practically precludes the use of Indocyanine Green as a biological stain. See: Sigma-Aldrich Handbook of Dyes, Stains, and Indicators, Green, F. ed., p. 407.
My question is not addressed here, how can I contact Technical Service for assistance?
Ask a Scientist here.
Show more questions

Milli-Q® Water Purification Solutions
Protocols & Articles
Peer-Reviewed Papers


Related Products

Technical Service:

Our team of scientists has experience in all areas of research including Life Science, Material Science, Chemical Synthesis, Chromatography, Analytical and many others.

Bulk Ordering & Pricing:

Need larger quantities for your development, manufacturing or research applications?