IRDye^® 800CW

IRDye 800CW:
The best choice for translation applications using NIR fluorescence

LI-COR Translational Research seeks to facilitate the use of IRDye 800CW imaging agents in clinical studies for detection of disease and its progression, and for monitoring of treatment and drug efficacy. IRDye 800CW has been conjugated to a variety of targeting agents by leading molecular imaging laboratories developing translatable agents. Unlike indocyanine green, which cannot be attached to biomolecules in its clinically approved form, IRDye 800CW reactive dyes are easily conjugated.

Absorption and scattering of light are largely a function of the wavelength. Endogenous chromophores present in living tissue including hemoglobin, melanin, and lipids, absorb visible light. Absorption and scattering decrease above 700 nm with an optimal wavelength for imaging centered at 800 nm. Above 900 nm, water absorption can compromise signal-to-background. In addition, tissue autofluorescence is minimal at 800 nm. The excitation and emission of IRDye 800CW is in the spectral region where tissue absorption, autofluorescence, and scattering are minimal yielding the highest signal to background ratios.

ICG: Before IRDyes were available, researchers pioneering the in vivo field had a very limited selection of commercially available dyes in the 800 nm region. Indocyanine green (ICG) has been used in the early literature as one of the only 800nm dyes approved for clinical retinal imaging. Unfortunately ICG use was limit because it was not available with a reactive group for conjugation to a targeting moiety for molecular imaging. ICG is also hydrophobic and is bound nonspecifically to serum proteins.

IRDye 800CW: LI-COR has been developing near infrared dyes for biological use for more than twenty years. IRDye 800CW was empirically designed for optimal performance in Western blotting and an immunocytochemical assay, the In-Cell Western, used for assessing cell signaling pathways in situ. The dye is highly water soluble and shows very low nonspecific binding to cellular components and yields very high signal. In animal studies, it has been shown to clear through the kidneys and is approximately twenty times brighter than ICG [in 2008].

In 2006, LI-COR Biosciences introduced the MousePod imaging accessory and the Pearl In vivo imaging system along with IRDye 800CW labeled optical probes for the research market. We have continued to collaborate with the leaders in the optical imaging field and the list of probes labeled with IRDye 800CW has continued to grow. The following IRDye 800CW-labeled probes have appeared in the literature:

Agent	Target	Application
Epidermal Growth Factor	EGF Receptor	A target over-expressed on many types of cancer cell lines and tumors
RGD peptide	Integrin	Invasion
2-Deoxyglucose	GLUT1	Areas of high metabolism
PEG polyethylene glycol	Vascular and lymph agent	Angiography and lymphadema
Vascular Endothelial Growth Factor	VEGF receptor	Angiogenesis
EGFR antibodies	Epidermal Growth Factor Receptor	A target over-expressed on many types of cancer cell lines and tumors
Tetracycline derivatives	Bone	Bone mineralization
PK11195 (Drug candidate)	Peripheral benzodiazeine receptor (PBR) is a trans-mitochondrial membrane protein that modulates steroid biosynthesis.	Up-regulation and nuclear localization of PBR has been shown to be associated with colon, prostate, and breast cancer.
IRDye 800CW NHS ester	-	Cytotoxic T lymphocyte migration
Activity-based probe	Cathepsin	Breast cancer angiogenesis and invasion
Butyrylcholinesterase	Butyrylcholinesterase	Biodistribution study

In 2009 LI-COR Biosciences announced the successful completion of animal toxicity studies for IRDye^® 800CW infrared dye carboxylic acid using a protocol reviewed by the Food and Drug Administration. Currently LI-COR is exploring options for additional studies as next steps in the FDA approval process leading toward clinical use. In expectation of clinical applications, LI-COR has established cGMP manufacturing of IRDye 800CW along with an FDA drug master file. We continue to work with collaborators to translate optical imaging agents to the clinic.