Orally administered gadolinium orthovanadate GdVO4:Eu3+ nanoparticles do not affect the hydrophobic region of cell membranes of leukocytes

To assess the phospholipid bilayer of white blood cells (WBCs) and the ability of leukocytes to generate reactive oxygen species (ROS) in rats orally exposed to GdVO₄:Eu³⁺ nanoparticle (VNP) solution for 2 weeks by fluorescent probes—ortho-hydroxy derivatives of 2,5-diaryl‑1,3‑oxazole.

Steady-state fluorescence spectroscopy, i.e., a study by the environment-sensitive fluorescent probes 2‑(2′-OH-phenyl)-5-(4′-phenyl-phenyl)-1,3-oxazole (probe O6O) and 2‑(2′-OH-phenyl)-phenanthro[9,10]-1,3-oxazole (probe PH7), and flow cytometry, i.e., analysis of 2′,7′-dichlorofluorescein (DCF), a product of a dye 2′,7′-dichlorodihydrofluorescein diacetate (H₂DCFDA), fluorescence in CD45⁺/7-aminoactinomycin D (7-AAD)⁻ cells, were used to evaluate the state of cell membranes and reactive oxygen species (ROS) generation in leukocytes of rats orally exposed to gadolinium orthovanadate nanoparticles(VNPs).

No significant changes were detected in the spectra of the fluorescent probes bound to the WBCs from the rats orally exposed to nanoparticles in comparison with the corresponding spectra of the probes bound to the cells from the control group of animals. This indicates that in the case of the rats orally exposed to nanoparticles, no noticeable changes in physicochemical properties (i.e., in the polarity and the proton-donor ability) are observed in the lipid membranes of WBCs in the region where the probes locate. There was no statistically significant difference in the amount of ROS^high viable leukocytes in rats treated with VNPs and control samples.

Neither changes in the physical and chemical properties of the leukocyte membranes nor in ROS generation by WBCs are detected in the rats orally exposed to VNP solution for 2 weeks.