The present invention disclose a very simple method for the synthesis of bioactive monodispersed cerium oxide fluorescent nanoparticles (quantum dots)/nanoparticles using aqueous extract of Justicia adhatoda leaf under mild environment at ambient temperature. The synthesis of cerium oxide fluorescent nanoparticles (quantum dots) generated by this method were found to be in the range of 2-4 nm in size characterized by transmission electron microscopy (TEM). Extraordinary monodispersity of cerium oxide fluorescent nanoparticles (quantum dots) was observed. Generated cerium oxide fluorescent nanoparticles (quantum dots) showed enhanced antioxidant activity and also mimic catalase which can be utilized in various domains of biomedical applications including diagnostics.
