[joshuahaglund]

How many times have we found a new medical use for an existing dye?

Prontosil was a pre-penicillin antibacterial based on azo dyes https://en.wikipedia.org/wiki/Prontosil#History

Brilliant blue, a food coloring, was found to help repair spinal injuries https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6719612/

[adonovan]

And the first antibiotic was inspired by the observation that dye stuck to bacteria better than other things! See https://en.wikipedia.org/wiki/Paul_Ehrlich

[foobiekr]

The blue dye seems to have gone nowhere since the initial study: https://en.wikipedia.org/wiki/Coomassie_brilliant_blue