Identifying characteristic properties and antioxidant effect of quercetin loaded titanium dioxide nanoparticles

Quercetin (Que) is strong antioxidant but its poor solubility limits its applications. Que could be designed at the nanoscale level and using nanoparticles for this purpose brings improved solubility, drug release and bioavailability. In this study, we aimed to determine characteristic properties of quercetin-loaded-PEGylated titanium dioxide nanoparticles (Q-PEGTiO2) and their biological effects. Firstly, TiO2 NPs were modified with polyethylene glycol to increase biocompatibility. Next, SEM and DLS were used to characterize Q-PEGTiO2 and results showed that bare TiO2 NPs tend to agglomerate and have larger size in water. Additionally, cellular viability of cells was analyzed after the treatments and we observed that while Q-PEGTiO2 showed lower toxicity, Que-treated cells lost their viability after 24 and 48 hour of treatment. Thereafter, cellular uptake of Q-PEGTiO2 and Que were detected by laser scanning confocal microscope and it was observed that they localized mainly in the cytoplasmic part. Penetration efficiency was determined by colocalization analysis and it was observed that the nanosystem reached its maximum levels at 12th hour. Lastly, DPPH radical scavenging assay was used to see antioxidant effect of the nanosystem and we observed that Q-PEGTiO2 has increasing scavenging activity over time. Here, we elucidated physicochemical identity of QPEGTiO2 with its low toxicity and higher antioxidant effect