Photo‐Modification of Melanin by a Mid‐infrared Free‐electron Laser,

Takayasu Kawasaki, Aomi Sato, Yuki Tominaga, You Suzuki, Takahiro Oyama, Makoto Tadokoro, Koichi Tsukiyama, Kiyoshi Nokihara, Heishun Zen

Pages: 946-950 | First Published: 05 January 2019

 

We applied a free‐electron laser tuned to mid‐infrared wavelength (5.8 μm) to irradiate melanin. The melanin powder was dispersed by the pulse irradiation with power energy of 500 mJ cm⁻², and the minimum pulse number for damage to the morphology of melanin was 2 macro‐pulses, which was equivalent to 1.4 s of irradiation. Analyses by mass spectroscopy, infrared spectroscopy, and ¹³C‐nuclear magnetic resonance implied that pyrrole group in the structure of synthetic melanin was dissociated by the FEL irradiation. In addition, melanoma cells were substantially damaged by FEL irradiation.