Oxidation of aqueous ∼8 nm unprotected copper nanoparticles takes place under air in approximately 2 hours at 30 °C to give Cu(2+) as a final product through an intermediate Cu(+) species. At 5 °C the process is about 5 times slower; similarly, vitamin C, which plays a sacrificial role, also slows down the oxidation, while CuNP catalyses the oxidation. In this work, we present a detailed analysis of the oxidation mechanism of colloidal CuNP inferred through spectroscopic methods (UV-visible and EPR) combined with oxygen uptake measurements, with emphasis on factors affecting the oxidative process.

A new and unusual class of chain-breaking antioxidants has been discovered, where the actual antioxidant is, paradoxically, a carbon-centered radical. Properties of these molecules are currently being studied. The solvent dependence on antioxidant activity of the HP-136 dimer has been measured, in solvents of varying H-bond accepting ability, by the inhibited oxygen uptake (IOU) method. As anticipated, the HP-136 dimer was found to show much less solvent effect on antioxidant activity than a representative phenolic antioxidant.

We report a novel method of identifying damage to DNA leading to the loss of intercalation sites. Thiazole orange (TO), an intercalating cyanine dye, fluoresces strongly when intercalated in DNA, but not free in solution. Upon UVC-induced damage to DNA, the change in TO fluorescence is greater than the change in any of the other spectral or biochemical indicators (absorbance, circular dichroism and agarose gel electrophoresis), thus providing a fast screening method to identify damage to DNA. The method is geared toward high levels of damage, such as those that may result during radiation treatment of food products.

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