Niobium-Based Conditioning Layer to Reduce Bacterial Adhesion and Biofilm Formation on Titanium Surface

Niobium metal has a wide range of applications; however, the development of Nb-coated surfaces with antimicrobial activity remains unexplored. This study investigates the antimicrobial and antibiofilm activities of ammoniacal niobium oxalate (ANO) and develops a methodology to deposit it on titanium-functionalized surfaces to prevent bacterial colonization and biofilm formation. ANO is dispersed in water and characterized for particle size, Fourier transform infrared spectroscopy, X-ray diffraction, ζ-potential, and in vitro cytotoxicity. Its antimicrobial activity is assessed by microdilution and inhibition halo assays against Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus mutans, Candida albicans, and Candida glabrata. Antibiofilm activity is evaluated through biomass quantification, respiratory activity, and morphological analysis. Titanium surfaces functionalized with polyacrylic-acid-ANO films are tested under dynamic flow conditions for their antifouling properties in a multispecies biofilm model. ANO particles (∼450 nm) exhibit a negative charge, high crystallinity, and low cytotoxicity. The compound inhibits both Gram-negative and Gram-positive bacteria, even at low concentrations, and reduces the metabolic activity of mature biofilms. However, it does not remove aggregates or prevent adhesion and biofilm growth on titanium surfaces, indicating the need for further optimization of the functionalization conditions.