Noam Eliaz

Zinc–tungsten coatings have been considered as environmentally friendly, and corrosion- and wear-resistant coatings. Here, Zn–W coatings were successfully electrodeposited from an aqueous solution. Citrate-based electrolytes with pH in the range of 3.0 to 5.7 were used as plating baths. The kinetics of co-reduction in the Zn(II)–W(VI)–Cit system was studied on the basis of partial polarization curves. The effects of applied potential, electrolyte composition, pH, hydrodynamic conditions and passed charge on the electrodeposition of Zn–W layers were determined. X-ray photoelectron spectroscopy confirmed the presence of metallic tungsten co-deposited with zinc. X-ray diffraction analysis revealed the formation of hexagonal Zn–W phase resulting from a substitution of Zn atoms by W atoms in the Zn crystal lattice. The formation of the proper stable and electroactive W(VI) and Zn(II) complexes is the first crucial factor enabling the induced codeposition of Zn–W alloys. The tungsten content in the Zn–W deposit is closely related to the concentration of electroactive tungstate–citrate species and its ratio relative to the zinc–citrate electroactive species in the electrolytic bath. The oxidation state of tungsten in the electrodeposited Zn–W layers can be controlled mainly by the applied deposition potential and by the bath pH, which determines the type of W(VI)–Cit species that can be reduced.

Digital light processing (DLP) is a vat photopolymerization 3D printing technique with increasingly broad application prospects, particularly in personalized medicine, such as the creation of medical devices. Different resins and printing parameters affect the functionality of these devices. One of the many problems that biomedical implants encounter is inflammation and bacteria growth. For this reason, many studies turn to the addition of antibacterial agents to either the bulk material or as a coating. Zinc oxide nanoparticles (ZnO NPs) have shown desirable properties, including antibacterial activity with negligible toxicity to the human body, allowing their use in a wide range of applications. In this project, we developed a resin of poly(ethylene glycol) diacrylate (PEGDA), a cross-linker known for its excellent mechanical properties and high biocompatibility in a 4:1 weight ratio of monomers to water. The material’s mechanical properties (Young’s modulus, maximum elongation, and ultimate tensile strength) were found similar to those of human cartilage. Furthermore, the ZnO NPs embedding matrix showed strong antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S.A.). As the ZnO NPs ratio was changed, only a minor effect on the mechanical properties of the material was observed, whereas strong antibacterial properties against both bacteria were achieved in the case of 1.5 wt.% NPs.