# Optimizing Titanium Osseointegration through Thermally Modified Co-Doped Monetite Coatings

## TL;DR

This study shows that Co-doped monetite coatings on titanium implants improve bone integration by enhancing cell adhesion and promoting blood vessel growth.

## Contribution

The paper introduces thermally modified Co-doped monetite coatings that address both osteogenesis and angiogenesis for better implant integration.

## Key findings

- Co-monetite coatings showed superhydrophilic properties and enhanced preosteoblast adhesion and spreading.
- Gene expression revealed upregulation of osteogenic markers and increased MMP-2/9 activity for extracellular matrix remodeling.
- Cobalt doping induced a pro-angiogenic response through HIF-1α stabilization, supporting vascularization.

## Abstract

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.