THE SENSITIVITY OF ANIMAL CELLS SENSITIZED WITH BILIRUBIN UNDER IRRADIATION OF SPECTRAL BLUE AND GREEN BAND

It has been shown that optical irradiation with LED sources of an emission band maximum at about 465 nm and 520 nm has substantially identical damaging effects on animal cells in culture that are in a logarithmic growth phase and pre-incubated with pigment. Photobiological effect is caused by photodynamic processes involving singlet oxygen generated by triplet excited sensitizer. Mono-exponential type dependence of cell survival on irradiative energy dose indicates that it is bilirubin that acts as a sensitizer but not its photoproducts. The inclusion of bilirubin in the cells where it is primarily localized in the mitochondria, is accompanied by a multiple enhanced photochemical stability compared to pigment molecules bound with albumin.