Tuesday, April 21, 2015

Product Focus: Biotium CF Dyes™ Range

CF™ dyes are a series of highly water-soluble fluorescent dyes spanning the visible and near-infrared (NIR) spectrum for labeling biomolecules, especially proteins and nucleic acids. Developed by scientists at Biotium using new breakthrough chemistries, CF™ dyes rival or exceed the quality of other commercial dyes, such as Alexa Fluor® dyes, due to the following novel features.

New rhodamine chemistry

Rhodamine dyes are known for their excellent photostability and good fluorescence quantum yield; consequently several of the Alexa Fluor® dyes bear the rhodamine core structure.

Unfortunately, traditional rhodamine chemistry makes it difficult to extend the fluorescence wavelength to the far-red region and even more challenging in the near-IR region, especially for water-soluble dyes for bioconjugation. Recently, Biotium scientists discovered a new way to prepare novel rhodamine dyes of any fluorescence color from green to near-IR.

The new chemistry is a key element in the development of many of our CF™ dyes, particularly our far-red CF™ dyes, which are not only bright and water-soluble but also extremely photostable.

Excellent labeling efficiency

Reactive dyes for bioconjugation are generally susceptible to hydrolysis, which can cause problems for shipping, handling and storage and result in lower labeling efficiency. Heavily sulfonated dyes, such as the Alexa Fluor® dyes, DyLight® dyes and IRDye® are particularly hygroscopic, worsening the hydrolysis problem.

For example, the percent of active Alexa Fluor® 488 succinimidyl ester (SE) could be well below 50% by the time of application (Alexa Fluor 488 microscale labeling kit product information sheet, Invitrogen). In contrast, all of Biotium’s amine-reactive CF™ dyes have a relatively stable form of SE, which is more resistant to hydrolysis than the SE in many of the Alexa Fluor dyes. Accordingly, CF™ dye SE products generally give consistently higher labeling efficiency, thus providing users a better value.

Multi-color flexibility

Biotium currently offers 20 CF™ dyes spanning the visible, far-red, and near-infrared spectra, with additional colors in development. The CF™ dye product line includes reactive dyes, secondary antibodies, streptavidin, phallodin and other conjugates, and antibody labeling kits.

Unrivaled near-IR dyes

Near-IR dyes are typically much larger in size than dyes in the visible range. The large size often results in serious problems of low dye solubility, dye aggregation and poor fluorescence quantum yield. To overcome the problems, many commercial near-IR dyes, such as the near-IR Alexa Fluor® dyes, DyLight® dyes and IRDyes®, are prepared by placing a number of negatively charged sulfonate group on the dyes. While sulfonation improves dye solubility and fluorescence quantum yield to some degree, it creates another even more serious problem: non-specific binding of the bioconjugates prepared from the dyes.

For example, conjugation to a highly negatively charged dye can dramatically alter an antibody’s isoelectric point (iP), which is essential for maintaining specific antibody-antigen interaction. With this insight, Biotium scientists devised a revolutionary new approach to near-IR dye design that results in superior physical properties of the dyes without introducing an excessive amount of negative charge.

Biotium’s near-IR CF™ dyes are based on the core structure of either cyanine dyes or rhodamine dyes. Those core structures are modified such that the intramolecular mobility of the dyes is restricted, which leads to higher quantum yield and better water solubility without adding excessive charge. As a result, near-IR CF™ dyes are much brighter and more photostable than any other near-IR dyes. Most importantly, antibodies labeled with near-IR CF dyes™ give far better signal-to-noise ratio in immunostaining compared with antibody conjugates prepared with other commercial near-IR dyes.

Where can I find more information about US Biological?

Visit the manufacturer page at www.stratech.co.uk/usbio, email info@stratech.co.uk or call +44 (0) 1638 782600.

Stratech Scientific is a distributor of high quality, competitively priced, reliable products for research laboratories throughout the UK and Europe. Please contact us to find out which ranges we can supply in your country.
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