Synthesis of "Naked" TeO 2 Nanoparticles for Biomedical Applications.

Chalcogenide nanoparticles have become a very active field of research for their optoelectronic and biological properties. This article shows the production of tellurium dioxide nanoparticles (TeO 2 NPs) by pulsed laser ablation in liquids. The produced nanoparticles were spherical with a diameter of around 70 nm. The energy band gap of those nanoparticles was determined to be around 5.2 eV. Moreover, TeO 2 NPs displayed a dose-dependent antibacterial effect against antibiotic-resistant bacteria such as multidrug-resistant Escherichia coli (MDR E. coli ) and methicillin-resistant Staphylococcus aureus (MR S. aureus ). The "naked" nature of the nanoparticle surface helped to eradicate the antibiotic-resistant bacteria at a very low concentration, with IC50 values of ∼4.3 ± 0.9 and 3.7 ± 0.2 ppm for MDR E. coli and MR S. aureus , respectively, after just 8 h of culture. Further, the IC50 values of the naked TeO 2 NPs against melanoma (skin cancer) and healthy fibroblasts were 1.6 ± 0.7 and 5.5 ± 0.2 ppm, respectively, for up to 72 h. Finally, to understand these optimal antibacterial and anticancer properties of the TeO 2 NPs, the reactive oxygen species generated by the nanoparticles were measured. In summary, the present in vitro results demonstrate much promise for the presently prepared TeO 2 NPs and they should be studied for a wide range of safe antibacterial and anticancer applications.