###### Abstract  
Early biofilm formation could be inhibited by applying a thin biocompatible copper coating to reduce periprosthetic infections. In this study, we deposited crystalline Cu-doped TiO\({}_{2}\) films using one-step DC magnetron sputtering in an oxygen atmosphere on a biased Ti6 Al4V alloy without external heating. The bias voltage varied from \(-25\) V to \(-100\) V, and the resultant substrate temperature was measured. The deposited coatings were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), microhardness, scratch and hydrophilicity tests, potentiodynamic polarization measurements, and antibacterial assays against _S. aureus_ and _E. coli_. The findings demonstrated that when a higher negative bias is applied, the substrate temperature drops, and the anatase to rutile transformation is initiated without indicating obvious Cu-containing phases. The SEM images of the films showed spherical agglomerates with homogeneously distributed Cu with decreasing Cu content as the bias value increased. Higher bias results in the grain refinement of the thinning coatings with more lattice microstrain and more defects, together with an increase in water contact angles and hardness values. Samples biased at \(-75\) V exhibited the highest adhesive strength between coatings and substrate, whereas the specimen biased at \(-50\) V demonstrated higher corrosion resistance. Cu-containing TiO\({}_{2}\) coatings with pure anatase phase composition and Cu concentrations of \(2.62\) wt.% demonstrated excellent bactericidal activity against both _S. aureus_ and _E. coli_. The layers containing \(2.34\) wt.% Cu exhibited very good antibacterial properties against _S. aureus_, only. According to these findings, the produced copper-doped TiO\({}_{2}\) coatings have high bactericidal qualities in vitro and may be used to prepare orthopaedic and dental implants in the future. DC magnetron sputtering; copper-doped TiO\({}_{2}\); substrate bias; anatase; rutile; _E. coli_; _S. aureus_; antibacterial properties +
Footnote †: journal: Applied  
0000-0001-9958-0888][PERSON]  
0000-0001-9958-0888][PERSON]. [PERSON]  
0000-0001-9958-0888][PERSON]. [PERSON] and M. D. (2020) 2020-0202-0203]M. P. and M. D. (2020) 2020-0203-2  
bone integration, putting the patients' health at risk and negatively affecting their quality of life [5]. Inorganic antibacterial agents like Ag, Cu, Zn, etc., have drawn interest due to their low costs and low danger of biological adverse effects [6], and their superior simplicity, stability, and effectiveness at low concentrations [7]. They are not Gram-specific (effective against only Gram-positive or Gram-negative bacteria) and do not cause antibiotic resistance. Due in part to decades of improper antibiotic use, germs that have become resistant to many traditional antimicrobial agents can be effectively combated by this novel method of bactericidal activity. In vitro studies have demonstrated that copper ions exhibit enhanced antibacterial activity while preserving biocompatibility when confronted with silver, zinc, cobalt, aluminum, and mercury ions [8]. Apart from its excellent antimicrobial properties, copper (Cu) is an essential trace element for all living organisms and is required for several physiological processes, such as respiration, energy production, and tissue development [9]. Because of its strong antibacterial action and low cytotoxicity, copper is presently considered a suitable doping agent of TiO\({}_{2}\)[2; 10]. The microstructure, phase, chemical composition, and crystallite sizes of the Cu-doped TiO\({}_{2}\) films are critical factors that impact their biological properties. Hence, there is a great desire to manage these qualities by appropriately adjusting the deposition process parameters. Wet chemical techniques such as electrochemical [11; 12], solvothermal/hydrothermal [13], sol-gel [14], etc., and RF/DC magnetron sputtering [15], are two prominent fabrication methods that show promise today to obtain Cu-doped TiO\({}_{2}\) coatings.