New Contrast Dyes Improve Medical Images, Reduce Prep Time

Thomas Just Sørensen (University of Copenhagen)

Chemistry researchers at University of Copenhagen in Denmark, with colleagues from two Texas universities, developed a new type of contrast dye for medical imaging that the inventors say cuts the time and labor needed for preparation. Their discoveries are described in a series of publications over the past five months, the most recent appearing in this month’s issue of the journal Analytical and Bioanalytical Chemistry (paid subscription required).

Thomas Just Sørensen, a Copenhagen postdoctoral researcher, is lead or co-author on the four scientific articles, with colleagues from University of North Texas Health Science Center and Texas Christian University, both in Fort Worth. Their research aims to solve a problem with medical imaging in highlighting biological targets, such as proteins and antibodies,  to separate these targets from surrounding tissue.

The earlier journal articles appeared in Analytical and Bioanalytical Chemistry, Journal of Physical Chemistry, and Methods and Applications in Fluorescence.

Current technologies for contrasting targets from surrounding tissue use a dyeing process that illuminates the target, but often with limited effect. One of the key problems with current contrast agents is the very short time the fluorescent dye stays illuminated when exposed to light, about 10 nanoseconds — 1 nanosecond equals 1 billionth of a second. That’s about the same amount of time natural tissue lights up when illuminated, thus the difficulty in imaging the dyed targets.

Sørensen and colleagues developed a new type of fluorescent dye called AzaDiOxaTriAngulenium, or triangulenium that decays more slowly on the target, providing an illuminated target for 100 nanoseconds, much more time than the surrounding tissue. In lab experiments, the researchers devised a technique where the very early light fluorescent signals were discarded, leaving illuminated the targets with the trangulenium dyes.

The team believes its new process not only works better, but can also reduce the time and cost needed to produce medical images needing contrast agents. Medical labs now spend a lot of preparation time in staining samples, say the researchers, since the samples need two separate dyes to provide adequate contrast. Not only do triangulenium dyes require only one treatment, viewing the images can be done with an ordinary microscope, and lens material similar to that in polarized sunglasses.

The university has not disclosed commercialization plans for the dyes, but Sørensen says he is offering them free of charge to other researchers who want to test triangulenium against current methods.

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