Non-cytotoxic molybdenum-based nanostructures as effective radical scavengers

Sodium molybdate is a potential candidate as an effective antioxidant even if no significant proof of its antioxidant properties has been reported so far, especially for nanoparticles. In the present work, we have synthesised sodium molybdate nanoparticles using MoS2 and NaOH as precursors. After thermal treatment at 200 °C for 20 hours, sodium molybdate nanoparticles with an average dimension of 26 nm have been obtained. An intermediate treatment time of 8 hours gives nanoparticles with a mixed composition, MoS2-Na2MoO4. The nanoparticles have been characterized using Raman and infrared spectroscopy, X-ray diffraction, atomic force microscopy and dynamic light scattering. The radical scavenging capability has been tested using 1,1-diphenyl-2-picrylhydrazyl as a molecular probe. Both pure Na2MoO4 and the heterostructured MoS2-Na2MoO4 nanoparticles have exhibited excellent radical scavenging activity in aqueous solutions, with MoS2-Na2MoO4 showing an enhanced response. Another test has been conducted in the solid state, introducing the nanoparticles within a mesoporous titania film matrix. The high photocatalytic activity of titania has been completely quenched by the presence of the sodium molybdate nanoparticles. Finally, in vitro studies using Hep G2 cells further confirmed the antioxidant capacity of the nanoparticles without inducing cytotoxicity. These findings suggest that sodium molybdate nanoparticles are promising candidates for biomedical and environmental applications, particularly in reducing oxidative stress.