An emulsion of pigmented nanoceria as a medicinal cosmetic
Formulating nanoparticle based cosmetics with medicinal values to protect skin from environmental stress is a challenging task nowadays. In our work, we have prepared an emulsion of bluish pigmented cerium oxide nanoparticles (nanoceria) with potent free radical scavenging activity. The nanoceria were prepared by conventional thermal decomposition, and encapsulated by the amine-containing polyethylenimine. Characterizations such as Nuclear Magnetic Resonances (NMR), Dynamic Light Scattering (DLS), Atomic Force Microscope (AFM), Transmission Electron Micrographs (TEM) and X-ray Diffractograms (XRD) showed that the nanoceria were near spherical, monodispersed and sized 3–10 nm. UV-vis analysis confirmed that the particles were pigmented whereas circular dichroism revealed that the secondary structure of collagen, a fibrillar protein present in skin, was not affected by the presence of these pigmented nanoceria. In vitro anti-oxidant assays showed that the pigmented nanoceria were more effective than non-pigmented nanoceria against nitrile and peroxy radicals, with their activity depending on the concentration of CeO2. Thus, the emulsion of pigmented nanoceria can be evaluated, in future, as a medicinal cosmetic for protecting the skin.