Structural, morphological, and cytotoxicity evaluation of surfactant-modified niobium oxides

The employment of metal nanoparticles for biomedical applications is gaining visibility as a result of their excellent properties. Niobium oxide (Nb₂O₅) possesses interesting physicochemical properties that can be modified for its use in prosthetic coatings. However, there are only a limited number of studies in the literature concerning its characterization as a pure powder, its surface modification and their cytotoxicity. Therefore, the purpose of this study was to evaluate nine different Nb₂O₅samples synthesized using the microwave technique, each with a different surfactant. x-ray diffraction results indicated that all samples were amorphous, and the addition of surfactants did not seem to cause any alterations, as indicated by Raman and FTIR. Scanning electron microscopy (SEM) images revealed that the particles tended to form aggregates; modification of parameters such as surface area and acid sites was also observed, with pure Nb₂O₅having the highest area (230.4 m²g^-1) and NbSDS5 having the highest total acidity (3141 µmol g^-1). We assessed the cytotoxicity in sheep's erythrocytes and the Zebrafish Liver (ZF-L) cell line. Pure Nb₂O₅exhibited high cytotoxicity at 10 mg ml^-1in red blood cells with an erythrocyte survival rate of 15%. The MTT assay that revealed that NbCA1 showed only 27.1% cell viability, while NbSDS1 was able to increase cell proliferation (101.1%) even at a lower pH. Compounds were also able to interfere with the intrinsic coagulation pathway, with several samples exceeding the clotting time (>120 s). Nb ions leaching to the medium does not seem to directly affect cytotoxicity. Pearson's correlation does not indicate a direct relationship between surface area, acid sites, and cytotoxicity assays.