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In this study, rosemary leaf extract was effectively used to synthesize cobalt oxide nanoparticles (Co3O4 NPs) using a rapid, low-cost, and environmentally friendly approach. The prepared Co3O4 NPs were examined using various analytical techniques. However, UV spectrum analysis displayed two sharp absorption peaks at ~350 and 745 nm. The dynamic light scattering and zeta potential measurements were used to evaluate the particle size and the effective stabilization of the synthetic nanoparticles in the suspensions. A semi-triangular pyramidal shape of the Co3O4 NPs with a wide particle-size distribution could be observed in the scanning electron microscopy images. The energy-dispersive X-ray spectrum confirmed their successful synthesis, as the experimental atomic percentages agreed with the theoretical values. Moreover, X-ray diffraction analysis revealed that the synthesized Co3O4 NPs had a cubic crystalline structure corroborating that of theoretical Co3O4. Additionally, the Co3O4 NPs were not toxic at ≤62.5 µg/mL for Hep G2 and at ≤31.25 µg/mL for Mcf7. Therefore, these unique environmentally friendly Co3O4 NPs at this safe concentration could be studied in the future for their therapeutic activity. [ABSTRACT FROM AUTHOR]

Magnetite Fe3O4 and spinel (2:1) and (4:1) NiFe2O4 magnetic nanoparticles (MNPs) were prepared by simple and affordable co-precipitation methods using an extract of star anise (Illicium verum) as a green reducing agent. The morphology and chemical composition of these MNPs were confirmed by field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, UV–visible spectroscopy, and X-ray diffraction (XRD). The synthesized magnetite Fe3O4 and spinel (2:1) and (4:1) NiFe2O4 MNPs were in the size range of 0.1–1 µm. The MNPs had irregular clustered platelets (magnetite Fe3O4) and pyramidal structures (spinel (2:1) and (4:1) NiFe2O4 NPs). The average sizes of the synthesized magnetite Fe3O4, and spinel (2:1) and (4:1) NiFe2O4 MNPs calculated using XRD analysis were 66.8, 72.5, and 72.9 nm, respectively. In addition to the characteristic absorption peaks of magnetite Fe3O4, those of spinel (2:1) and (4:1) NiFe2O4 MNPs were detected at ~300–350 nm and ~700 nm, respectively. Overall, the results of this study indicate that the synthesized magnetite Fe3O4, and spinel (2:1) and (4:1) NiFe2O4 MNPs showed high biomedical activities against liver carcinoma cells and non-small lung adenocarcinoma cells. [ABSTRACT FROM AUTHOR]