Increase Sensitivity for Low Fluorescence Signals

The Krome Orange from Beckman Coulter Inc. is a novel violet-excited organic dye that expands the range of available choices and dye sensitivity limits for violet lasers. Common gating markers can be easily transferred to this fluorochrome, freeing other channels for use with more esoteric markers and enabling more versatile 10-color flow cytometry applications.

Krome Orange has excitation and emission maxima of 398 nm and 528 nm respectively and provides a brighter signal than Pacific Orange* conjugates with equivalent spectral overlaps into adjacent channels. The new dye is at least as bright as V500 and can provide more than twice the population separation obtained with Pacific Orange dye conjugates, with little compensation compared to Pacific Blue* dye.

Krome Orange conjugates show optimal performance with violet laser excitation and a 550/40 bandpass filter (the standard FL10 channel on flow cytometry systems), while no excitation is detected using a 488 nm laser. The initial release of Krome Orange includes conjugates to human CD45 and CD4, with the range of human and mouse targets to expand going forward.

“Krome Orange provides scientists with the ability to increase sensitivity for low fluorescence signals and to expand their flexibility for multi-color flow cytometry experiments,” said Brad Calvin, vice president and general manager of the Beckman Coulter Flow Cytometry Business Center. “The development of this new dye underscores Beckman Coulter’s commitment to expand multi-color cellular analysis technologies.”