Currently, only three dyes with fluorescent properties used as optical imaging contrast agentsโmethylene blue, indocyanine green and fluoresceinโare approved for human use by the U.S. Food and Drug Administration (FDA). ย In diagnostic medicine and in some surgical procedures, imaging contrast agents are materials used to improve internal body picturesโฆ These materials can be ingested or injected and temporarily color targeted parts of the body, like specific cells, organs, blood vessels and tissues, to help clinicians see differences and abnormalities that may indicate disease.
Yet, [researcher Cristina] Zavaleta wondered about the significant catalogue of approved food, drug and cosmetic dyes that people routinely encounter in their everyday lives. Are there other imaging agents hiding in plain sight?
โAs my art brain was thinking about these paints [from class], I thought to myself, what paints are already being used in humans?โ says Zavaleta. โAnd a lightbulb went off.โ
Tattoos. High quality pigments used in tattooing are made from mineral salts and metal chelates, which have been isolated from natural sources and used by humans for thousands of years.
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Data from Zavaleta and her colleaguesโ study showed that FDA-approved Green 8 dyes used in drugs and cosmetics have significant tumor targeting potential in mice with cervical and colon tumors, and the Orange 16 pigment found in tattoo inks also showed, according to the authors, promising fluorescent properties and tumor targeting potential.
