Chlorotoxin

Chlorotoxin, a relatively small (36–amino acid) peptide is what makes the venom of the deathstalker scorpion (Leiurus quinquestriatus) poisonous. In 1991, J. A. DeBin and G. R. Strichartz at Harvard Medical School discovered that its mode of toxicity is to block small-conductance chloride channels, which results in paralysis.

Chlorotoxin preferentially binds to glioma cells, which prompted researchers to investigate it as a tool for diagnosing and treating some cancers. Building upon much of this research, J. M. Olson at Fred Hutchinson Cancer Center (Seattle) discovered a way to use chlorotoxin to image cancer cells—a product he calls Tumor Paint. An unusual aspect of Olson’s work is that he funded it via crowdsourcing when he couldn’t obtain grant money through the normal channels.