Low-Temperature Synthesis of Monetite/Dextran Hybrid Coatings with Tailored Corrosion Resistance on Ti6Al4V

Hybrid coatings composed of crystalline monetite (CaHPO₄) and kefir-derived Dextran were synthesized on Ti6Al4V substrates using a low-temperature sol-gel-assisted route (≤80 °C), enabling biopolymer integration without thermal degradation. X-ray diffraction (XRD) confirmed the formation of triclinic monetite nanocrystals (∼152 nm), while Fourier transform infrared (FTIR) and scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS) analyses verified the uniform incorporation of Dextran, particularly in the 4 wt % formulation, which yielded compact, homogeneous surfaces. Electrochemical evaluations in Fusayama artificial saliva revealed a substantial enhancement in corrosion resistance, with the open-circuit potential shifting from -0.272 V (uncoated) to -0.034 V and polarization resistance increasing from 1987.6 to 5573.4 Ω. This performance surpasses several benchmark coatings reported for biomedical alloys, highlighting the synergistic interaction between the inorganic phase and the biopolymeric matrix. The hybrid architecture promotes defect sealing, barrier formation, and interface stabilization. These results position the monetite/Dextran system as a scalable, sustainable, and biocompatible solution for next-generation implant coatings, offering a mild-temperature alternative to traditional ceramic deposition methods.