Investigation of ROS scavenging properties and in vitro cytotoxicity of oxygen-deficient La2O3-x nanostructure synthesized by spray pyrolysis method


Oxygen-deficient metal oxides have seen increased application in the field of free radical biology, whereby their electronic structure imparts unique antioxidant properties. In this work, we use the facile, one-step, cost-effective method of spray pyrolysis to synthesize oxygen-deficient lanthanum oxide (La2O3-x), nanoparticles. Structural and morphological characterization revealed the formation of an aggregate of La2O3-x nanocrystals in the form of hollow spheres. Photocatalytic activity (PCA) was benchmarked against commercial La2O3 and Evonik Aeroxide® TiO2 P25 via dye degradation experiments and a significant pH dependence of PCA is reported. Furthermore, chemical assays based on the Fenton reaction verified the scavenging properties of the synthesized materials towards reactive oxygen species (ROS), with increased scavenging of hydroxyl (OH) and superoxide (O2∙–) radicals observed at pH 4.8. Biological assays (in vitro), with a 24 h incubation period in the presence of the La2O3-x nanoparticles, were conducted upon a non-malignant human keratinocyte cell line (HaCaT). The La2O3-x nanoparticles showed no toxicity when compared with the control over a significant concentration range. Biocompatibility with the non-malignant HaCaT cell line suggests the future application of La2O3-x as a doping material for inorganic oxides used as UV filters or as an antioxidant to mitigate oxidative stress by scavenging free radicals in conditions such as melanoma and inflammation.

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This research work is a part of University of Wollongong (UOW) Global challenge program “Next Generation Sunscreens”, carried out at the Institute of Super Conducting and Electronic Materials (ISEM), Australian Institute for Innovative Materials (AIIM), and the Illawarra Health & Medical Research Institute (IHMRI), UOW. In addition, the financial support also provided under the joint scholarship program of Higher education commission (HEC) Pakistan and UOW, Australia. We would like to thank Dr. Dongqi Shi (ISEM, UOW) for his assistance in XPS measurements. Furthermore, the authors acknowledge the use of Electron Microscopy facility (EMC), AIIM, at University of Wollongong, Australia.

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Rehman, Y., Copet, C., Morlando, A. et al. Investigation of ROS scavenging properties and in vitro cytotoxicity of oxygen-deficient La2O3-x nanostructure synthesized by spray pyrolysis method. J Nanostruct Chem (2020).

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  • Spray pyrolysis
  • Oxygen deficient
  • Reactive oxygen species
  • Photodegradation
  • Radical scavenging