Cu/Zn-doped PEO titanium with waveform-tunable bioactivity for dental implants

Peri-implant diseases remain a leading cause of dental implant failure, creating a need for surfaces that simultaneously support soft and hard tissue integration and limit bacterial colonization. In this context, Plasma Electrolytic Oxidation (PEO) represents a promising single-step surface treatment capable of producing hydrophilic, microporous titanium oxide layers that can be doped with functional ions. Here, copper (Cu) and zinc (Zn) were incorporated into PEO coatings on grade-2 titanium using an alternating-current process in which only the electrical waveform was varied, yielding two doping levels (CuZn-10 and CuZn-20) while largely preserving the overall PEO surface topography. All PEO coatings produced uniformly microporous surfaces markedly more hydrophilic than untreated titanium, and waveform control reproducibly tuned the amount of incorporated Cu and Zn. This differential doping translated into distinct biological behavior: the lower-dose CuZn-10 surface best supported human gingival fibroblast and osteoblast responses, promoting collagen deposition, alkaline phosphatase activity, and matrix mineralization, whereas the higher-dose CuZn-20 exerted a stronger, dose-dependent effect on Staphylococcus aureus and Aggregatibacter actinomycetemcomitans at the cost of reduced cytocompatibility. CuZn-10 therefore provided the most favorable balance between tissue integration and bacterial control. Overall, waveform-controlled Cu/Zn incorporation acts as a form of biofunctional programming, allowing the biological and antibacterial response of titanium implants to be tuned through a single processing parameter, with potential relevance for both dental and orthopedic applications.