Nanoestruturas à base de nióbio funcionalizadas com antioxidantes naturais: uma abordagem para aplicações biomédicas de alto desempenho

Abstract

Ascorbic acid (AA), tannic acid (TA), and quercetin (QUE) are natural antioxidants that exhibit potential in the treatment and prevention of various diseases. However, their efficacy is limited by low absorption and degradation under physiological conditions. Niobium (Nb) is a transition metal that presents good chemical stability in aggressive environments, corrosion resistance, and potential for composing biocompatible materials for biomedical applications. In this study, hydrated niobium oxide was synthesized and functionalized with AA, TA, and QUE to obtain nanostructured systems with bioactive properties. The synthesis involved dissolving the metallic precursor (NbCl5) in deionized water, and the functionalization was carried out using two methods: (1) during the reduction of the metallic precursor and synthesis of the non-functionalized material, and (2) after the synthesis process, by immersing the base material in a solution containing the antioxidants of interest. The materials were characterized by UV-Vis spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, Raman spectroscopy, X-ray diffraction (XRD), scanning and transmission electron microscopy (STEM), scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM/EDX), and zeta potential measurements. The results indicate the formation of nanostructured materials based on hydrated niobium pentoxide (Nb2O5·nH2O), a characteristic that was preserved even after functionalization with the antioxidant compounds, regardless of the method employed. Zeta potential measurements and EDX analyses indicate that Method 2 was more effective in producing more dispersed systems with higher concentrations of bioactive compounds. Regarding the cell viability assays, the functionalization processes, regardless of the method and antioxidant used, increased the cytotoxic concentration threshold of the non-functionalized material from 62,5 to 125 μg mL-1. Finally, all materials exhibited activity against Escherichia coli biofilm formation. Furthermore, except for the niobium-based nanostructures functionalized with AA, the synthesized materials also demonstrated bactericidal properties. Therefore, it can be concluded that the synthesis and functionalization of Nb-based nanostructured materials proposed in this work represent a promising strategy to expand the use of Nb in biomedical applications.