Optimizing Titanium Osseointegration through Thermally Modified Co-Doped Monetite Coatings

Although Ti implants have been used clinically for decades, their osseointegration is still a major concern in aged, diseased and osteoporotic patients. Using a hydrothermal synthesis approach, monetite (CaHPO₄) and Co-monetite coatings with controlled crystallinity and surface topography were designed and produced. Structural characterization via X-ray diffraction (XRD) confirmed the formation of phase-pure monetite (triclinic) with homogeneous cobalt distribution, while scanning electron microscopy (SEM) and profilometry revealed microstructured surfaces featuring peaks and valleys, mimicking native bone morphology. Remarkably, the coatings exhibited superhydrophilic properties for Co-monetite versus uncoated Ti. Biological assessments demonstrated excellent cytocompatibility using preosteoblasts, with MTT assays showing higher metabolic activity in Co-monetite groups compared to control. SEM analysis revealed enhanced preosteoblast adhesion and spreading on Co-monetite surfaces by day 7. Gene expression profiling uncovered significant upregulation of osteogenic markers, while zymography further demonstrated increased both MMP-2/9 activity, indicating active extracellular matrix remodeling. Altogether, these findings highlight the dual functionality of Co-monetite coatings toward (1) the physicochemical properties that promote osteoblast adhesion and early differentiation, and (2) cobalt doping, that induces a pro-angiogenic response through HIF-1α stabilization. By addressing both osteogenesis and vascularization, two critical challenges in implant integration, this research provides a foundation for the rational design of multifunctional biomaterial coatings for orthopedic and dental applications. The results suggest that Co-monetite coatings are a promising strategy to enhance the osseointegration of bone implants, warranting further preclinical investigation.