Fig. 6From: Revisiting the paradigm of silica pathogenicity with synthetic quartz crystals: the role of crystallinity and surface disorderCarbon-centred free radicals generated in an aqueous suspension containing sodium formate after incubation with quartz particles for 10, 30 and 60 min. Carbon-centred radicals result from homolytic cleavage of a C-H bond in the formate ion. Representative spectra in panel (a) were collected after 60 min of incubation. The signal intensity is proportional to the amount of radicals generated. The kinetics of carboxyl radical formation (b) was calculated by double-integration of the peak areas of collected spectra and expressed in arbitrary units. Experiments were performed in duplicate and reported as means ± SD. While as-grown quartz crystals (μ-Qz-syn, n-Qz-syn) showed no radical reactivity, fracturing (μ-Qz-syn-f) induced a strong, sustained reactivityBack to article page