Effects of cell proliferation inhibitors investigated by delayed luminescence spectroscopy

The possibility of using phot-induced Delayed Luminescence (DL) of living cells to monitor the effects of some cancer treatment that inhibit cell proliferation and induce apoptosis has been investigated. Different human cancer cell lines were investigated and DL measurements from liquid suspension of cultured cells, in the time interval 10 µs – 1 ms after the switching off of the illumination source, were performed on treated samples and compared to untreated ones. In particular the time decay of two spectral components, the blue (emission wavelength 460 nm) and the red components (emission wavelength 645 nm) were analyzed.The obtained data showed to be consistent with an important role of the Mitochondrial Respiratory Chain in DL emission. Changes in DL parameters can be correlated to apoptosis level. In particular changes in the DL blue component (connected to the mitochondrial level of nicotinamide adenine dinucleotide, NADH) may be a hallmark of induced apoptosis, while the response in the red spectral range may be ascribed to oxygen effects, as or Protoporphyrin IX emission quenching (that could be correlated to iron homeostasis in the cell) or dimol photoemission generated by two colliding molecules of singlet oxygen charge (that could be correlated to recombination in Fe/S redox centers in Complex I).