In this research, the cerium oxide nanoparticles (CeO2-NPs) were first synthesized using Spirulina platensis microalgae with mean particle sizes of around 20 nm. Physical-chemical properties of CeO2-NPs including FE-SEM, TEM, FTIR, XRD, and DLS were analyzed. CeO2-NPs were nano-encapsulated based on ultrasonic emulsification methods to improve the efficiency of the biological studies. The particle size of synthetic cerium oxide nanoemulsion (CeO2-NE) was found around 60 nm and their morphology, size, and stability were verified by TEM, SEM, DLS, and surface zeta-potential data, respectively. Antioxidant, antimicrobial against Escherichia coli and Staphylococcus aureus, and cytotoxic (on cancer cell line HT-29 and normal cell HFF) were performed comparatively between CeO2-NE and CeO2-NPs by FRAP/ABTS, MIC, and MTT assays, respectively. Moreover, apoptotic (caspase-3, caspase-8, and caspase-9) and antioxidant (superoxide dismutase, glutathione peroxidase, and catalase) related genes expression were determined in HT-29 treated cells with the CeO2-NE by Q-PCR. Due to the increased bioavailability and solubility, the CeO2-NE showed a much greater effect on anticancer activity (in a dose- and time-dependent manner), growth inhibition of two bacterial strains, antioxidant capacity, and reduction of ferric ions. Overexpression of caspase-3, caspase-8 and, caspase-9 of CeO2-NE confirmed apoptosis. Upregulation of superoxide dismutase (in all three concentrations) attributed to the cellular redox potential of CeO2-NE in HT-29 human cancer cells. In conclusion, the higher bioavailability of CeO2-NE provides more efficient biological applications that could turn it into a promising factor for cancer treatment.

Keywords