Modificações superficiais em pentóxido de nióbio: avaliação estrutural, atividade citotóxica e resposta biológica em Drosophila melanogaster

Abstract

The search for novel biomaterials has triggered the investigation of metal oxides, particularly niobium oxide (Nb₂O₅), given its corrosion resistance, chemical inertness, and economic importance to Brazil. Nb₂O₅ possesses great applications in catalysis, metallic coatings, glass, and polymers, exhibiting an alteration on cell proliferation and adhesion, with a decrease in inflammatory marker levels. However, there is an absence of research about its surface modifications and biological interactions. This study aimed to physicochemically characterize and evaluate the in vitro cytotoxicity and in vivo toxicity of surface-modified niobium oxides using different surfactants, namely citric acid, oleic acid, sodium dodecyl sulfate (SDS), and cetrimonium bromide. The Nb2O5 samples were analyzed using Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and X-ray diffraction (XRD), but no addition of functional groups from the surfactants was detected. Pure Nb2O5 exhibited the highest surface area (230.4 m²/g) using the Brunauer-Emmett-Teller technique, while Nb2O5 modified with 0.5 mmol of SDS (NbSDS5) showed the highest acidity (3141 µmol/g), as assessed by ammonia desorption. Through in vitro and in vivo analyses, a dose dependent behavior was observed for hemolytic activity, ranging from 1 to 10 mg/mL, with pure Nb2O5 being highly cytotoxic to erythrocytes (85% cell death) and modulating the intrinsic coagulation pathway. Furthermore, cytotoxicity assays indicated cell proliferation for Nb2O5modified with 0.1 mmol of SDS (NbSDS1), even under low pH conditions, but apparently without correlation to the release of Nb ions into the medium. Oral exposure using Drosophila melanogaster (10× and 50× the IC50 of hemolytic activity) demonstrated that even acute administration (72 h) was capable of altering parameters such as glucose, non-protein thiols (NPSH), and reactive species. However, it did not modulate triglyceride levels or lipid peroxidation, which may indicate a protective effect of adipose tissue, as NPSH levels increased. These studies demonstrate, for the first time, the exposure of Nb2O5to erythrocytes, hepatocytes, the coagulation pathway, and an animal model of D. melanogaster.