Tokyo, Japan – Researchers from Tokyo Metropolitan University have developed a new dye that can strongly absorb second near-IR radiation and transform it to heat. Starting with a dye from the bile pigment family, they designed a unique ring structure which can bind rhodium and iridium. Measurements and modeling revealed strong second near-IR absorptions and exceptional photostability. Second near-IR waves easily penetrate human tissue; the new dye may be applied in deep tissue therapies and imaging.