Antibacterial and biocompatible zinc-containing coatings on titanium for cranial defect repair

Complex cranial defects resulting from trauma or oncological diseases present a significant clinical challenge. Titanium implants are the most promising for the reconstruction of large cranial defects due to their biocompatibility, ease of handling, strength, and low infection rate. In this work, comparative studies of the physicochemical and biological properties of three types of zinc-containing micro-arc biocompatible coatings were conducted: coatings based on zinc-substituted hydroxyapatite Ca8Zn2(PO4)6OH2 (Zn-HA), and coatings based on tricalcium phosphate and wollastonite in combination with zinc oxide ZnO (Zn-TCP and Zn-Wol). The coatings were applied to fragments of a cranioplasty mesh, fabricated from Ti-6Al-4V titanium alloy using 3D printing. Surface morphology, internal structure of the coatings, elemental and phase composition were investigated using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). The biocompatibility of the coatings concerning 3T3 cells was assessed using the MTT assay. The antibacterial properties of the coatings were determined using Staphylococcus aureus (S. aureus). It was found that with an identical zinc concentration in the three electrolyte compositions, equal to 7.4 g-ion / L, the Zn content in the Zn-HA coating was 0.6 at.%, an order of magnitude lower than in the Zn-TCP and Zn-Wol coatings. The antibacterial activity for the Zn-HA, Zn-TCP, and Zn-Wol coatings was 87.3 %, 98.2 %, and 99.9 %, respectively. Meanwhile, the viability of 3T3 cells after cultivation with coating extracts was 86 %, 101.9 %, and 89 %, respectively. Consequently, the Zn-TCP coatings exhibit the highest bacteriostatic effect against S. aureus and the highest cytocompatibility towards 3T3 cells.

1. Government research assignment for ISPMS SB RAS - project FWRW-2026-0004