Hydroxyl radical production induced by plasma hydrogenated nanodiamonds under X-ray irradiation

For the first time, overproduction of hydroxyl radicals (HO center dot) induced by plasma hydrogenated detonation nanodiamonds (H-NDs) under X-ray irradiation is reported. Using coumarin (COU) as a fluorescent probe, we reveal a significant increase of 40% of the HO center dot production in the presence of H-NDs (6-100 mu g ml(-1)) compared with water alone. This effect is related to the negative electron affinity of the hydrogenated nanodiamonds and illustrates the ability of H-NDs to produce reactive oxygen species probably via electron emission in water under X-ray irradiation.