Synthesis of “Naked” TeO₂Nanoparticles for Biomedical Applications

Abstract

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.

Synthesis of Ultrawide Band Gap TeO2 Nanoparticles by Pulsed Laser Ablation in Liquids: Top Ablation versus Bottom Ablation

“…By using the Tauc plot methodology, their energy band gap was determined to be around ∼5.8 eV ( Figure 8 d). Both values of energy band gap are in agreement with the values reported in the literature, Khalef 29 and Hesabizadeh et al 30 Theoretically, it is well known that by shrinking the size of a semiconductor, its energy band gap increases. 42 At the nanoscale, size effects may have two origins: surface effects and quantum effects.…”

“…Colloids produced by both PLAL protocols are shown in Figure 2 . Both colloids exhibited a dark gray color, characteristic of TeO 2 nanoparticles being produced, as already observed by Khalef 29 and Hesabizadeh et al 30 By shining a red laser pointer through the colloid, the red laser light (λ = 650 nm) is being scattered, indicating the presence of particles within the sample. This phenomenon is known as the Tyndall effect.…”

“…Consequently, TeO 2 nanoparticles synthesized in ethanol were more stable than the ones synthesized previously in 2022 in deionized (DI) water, as the ζ-potential in DI water at that time was measured to be around −8 mV. 30 Finally, it is interesting to note that the higher ζ-potential value obtained for the colloid synthesized with the Bottom-ablation synthesis protocol is correlated to a larger pH change and a larger temperature change during the irradiation. In the literature, Ali et al 40 also found that the pH of the nanofluids decreases when the temperature increases.…”

“…So far, they have been produced by different methods such as spray analysis, sonochemistry, hydrothermal, , evaporation, biosynthesis, wet chemistry, and pulsed laser ablation in liquids (PLAL, Table ). − PLAL offers several advantages in comparison to other synthesis techniques. First, PLAL does not require capping ligands as wet chemistry does. − Specifically, PLAL produces nanoparticles with clean surfaces because it relies on electrostatic repulsion instead of stearic repulsion.…”

TeO2: A Prospective High‐k Dielectric

“…[ 30 ] This improvement could be due to the increase in nanocrystalline nature of the films with the increase in growth temperature. [ 31 ] The presence of TeO 3 units has a shorter bond length compared to TeO 4 units that can also be a factor in improving the bandgap. [ 32 ] Because of the wide bandgap at higher deposition temperatures, we have adopted 500 °C films in the later part of the study.…”