Impact of Nb₂O₅ Coating Produced by Using the Reactive Sputtering Technique on Bacterial Biofilm Formation

The reactive sputtering technique has been employed to deposit niobium pentoxide (Nb₂O₅) thin films onto the surfaces of the Ti-6Al-4 V alloy, which is widely used in trauma care and tissue repair. This approach has shown significant potential in enhancing the alloy's resistance to uniform and localized corrosion, as well as improving its wear and fatigue performance. In this study, Nb₂O₅ thin films were deposited on Ti-6Al-4 V surfaces using reactive DC sputtering, and their biofilm-modulating effects were evaluated in the presence of artificial saliva (AS) and two clinically relevant bacteria strainsStaphylococcus aureus ATCC 25923 (Gram-positive) and Escherichia coli ATCC 25922 (Gram-negative). The extent of biofilm coverage, expressed as a percentage, was quantitatively assessed using scanning electron microscopy (SEM) coupled with energy-dispersive spectroscopy (EDS). This combined analytical approach allowed for detailed morphological examination of the biofilm's distribution. Results demonstrated that the uncoated Ti-6Al-4 V surfaces exhibited 99.83% organic retention after saliva exposure and up to 74.94% biofilm coverage with E. coli, while Ti-6Al-4 V/Nb₂O₅ specimens showed lower retention under the same conditions (85.11 and 51.10%, respectively). Notably, S. aureus adhesion was markedly reduced on the coated samples (67.42%) when compared to that on the AS sample (40.68%), suggesting species-specific modulation of bacterial colonization. These findings indicate that Nb₂O₅ coatings can alter the surface wettability and biofilm architecture, reducing nonspecific organic adsorption and selectively influencing bacterial adhesion. This study underscored the potential of Nb₂O₅ coatings for the development of multifunctional biomedical surfaces exhibiting both antimicrobial and biointeractive properties.