Nanoceria were synthesized by discharging plasma at 800 V with a frequency of 30 kHz for 0-25 min using a pulsed unipolar power supply into solutions containing 1 or 2 mM of Ce(NO3)2. UV-Vis spectroscopy showed a characteristic absorbance maxima at 304-320 nm for the nanoceria with increase in the intensity of the peaks as the concentration of Ce(NO3)2 increased. The peaks exhibited transition red shift due to nanoceria formation. High resolution transmission electron microscopy revealed that spherical nanoparticles with an average size of 7.0 ± 0.2 nm were formed by discharging plasma for 15 min. The nanoceria showed excellent pH dependent antioxidant properties in hydroxyl and superoxide anion radical scavenging assays. Effect of the nanoceria on cell viability in vitro and inhibition of reactive oxygen species (ROS) by the nanoceria were examined using HeLa cell lines. As the results, no toxic effect was found up to 1600 μg mL-1 of nanoceria and they had an effective antioxidant property. Therefore, the nanoceria synthesized by one-step solution plasma process without employing hazardous chemicals have potential for utilization as antioxidant biomaterials and sustained release in the stream to scavenge ROS in the modern medicine.
Keywords: Antioxidant activity; Biocompatibility; Free radicals; Nanoceria; Reactive oxygen species; Solution plasma process.
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