Structural characterization and degradation analysis of molybdenum-doped β-tricalcium phosphate

This study presents the first comprehensive investigation of molybdenum-doped β-tricalcium phosphate (Mo-β-TCP) synthesized via precipitation and sintered at 1000 °C, examining structural modifications and degradation behavior at 2%, 4%, and 6% mol Mo concentrations. XRD analysis confirmed successful Mo ions incorporation into the β-TCP lattice, with predominantly β-TCP phase and minor Ca₂P₂O₇ traces, revealing systematic unit cell contraction from 3490.9 ų for pure β-TCP to 3474.3 ų for 4% Mo due to Ca²⁺ substitution by smaller Mo⁶⁺ ions. Crystallite size analysis demonstrated non-linear behavior, decreasing from 675 nm (pure) to 177 nm (4% Mo), indicating optimal structural disruption at intermediate doping. FTIR spectroscopy revealed systematic phosphate vibrational mode shifts and Mo=O stretching at ~453 cm⁻¹, confirming MoO₄²⁻ tetrahedral substitution. TEM analysis showed morphological evolution from spherical to faceted, aggregated structures with enhanced surface roughness. UV–Vis spectroscopy maintained high visible reflectance (>95%) while demonstrating bandgap narrowing through d-d electronic transitions. Ion release studies in PBS revealed dramatically altered dissolution kinetics, with enhanced calcium/phosphorus release and controlled Mo ion release (2–8.2 mg/L) within biocompatible ranges. The 4% Mo concentration demonstrated an optimal balance between structural modification and phase stability, exhibiting maximum unit cell contraction, the smallest crystallite size, and enhanced dissolution characteristics. These findings establish Mo-doped β-TCP as a promising biomaterial with tailored degradation properties and potential antimicrobial functionality for bone tissue engineering applications.