Scientists at HHMI’s Janelia Research Campus have developed a new method for fine-tuning the structure of rhodamine dyes, and can now create a colorful palette of fluorescent molecules.

With a new technique to craft a spectrum of glowing dyes, chemists are no longer chasing rainbows.

Swapping out specific chemical building blocks in fluorescent molecules called rhodamines can generate nearly any color scientists desire –­ ­ROYGBIV and beyond, researchers report September 4, 2017 in the journal Nature Methods.

The work offers scientists a way to adjust the properties of existing dyes deliberately, making them bolder, brighter, and more cell-permeable too. Such an expanded palette of dyes could help researchers better illuminate the inner workings of cells, said study leader Luke Lavis, a group leader at the Howard Hughes Medical Institute’s Janelia Research Campus in Ashburn, Virginia. His team lit up cell nuclei, made larval fruit fly brains shine, and highlighted visual cortex neurons in mice that had tiny glass windows fitted into their skulls.

Scientists used to concoct different dyes mostly by trial and error, Lavis says. “Now, we’ve figured out the rules, and we can make almost any color.” His team’s method could allow chemists to synthesize hundreds of different colors.