Chemistry in Pictures: Rhodamine RGB

Hot off the preparative-scale HPLC, these dye samples are headed for quality control and purity checks. Despite the intense color, there is only a tiny amount of dye in each vial—micrograms. Jon Grimm has made a fleet of the specialty dye molecules by making systematic alterations to a class of molecules called rhodamines (generic structure shown). Grimm is a senior scientist at the Howard Hughes Medical Institute’s Janelia Research Campus. He’s working with group leader Luke Lavis to develop “bright, photostable, cell-permeable dyes for advanced biological imaging, including single-molecule localization microscopy and single-particle tracking,” he says. Not just colorful, the rhodamines are fluorescent, absorbing at 575, 650, and 725 nm and emitting at 600, 675, and 750 nm, from left to right. Grimm says that in addition to their bright coloration, rhodamines permeate well into a wide range of tissues and cells.As a molecular scaffold, rhodamines also offer several sites to swap out heteroatoms and functional groups, a feature that can help in the search for new optical and chemical properties, such as protein targeting. Grimm has been working with rhodamines for roughly 11 years and is still eager to keep exploring their permutations and applications. “We are happy to freely share our dyes/probes with anyone who wants to try them,” he says, just reach out to him or Lavis.

Credit: Jon Grimm/HHMI, (@dyerfulchymist on Instagram, @jonathangrimm on Twitter).

Read more about the research here: Nat. Methods. 2020, DOI: 10.1038/s41592-020-0909-6; J. Am. Chem. Soc. 2021, DOI: 10.1021/jacsau.1c00006

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