Controlled EGCG Release from Zeolite-Coated Ti6Al4V: Effects of Divalent Ions on Release and Cytotoxicity

This study presents the development of titanium-based implants coated with zeolite layers for controlled delivery of epigallocatechin gallate (EGCG), a polyphenolic compound with osteogenic, antiresorptive, and antibacterial properties. Zeolite coatings were modified with divalent ions (Zn²⁺, Mg²⁺, Ca²⁺) to investigate their influence on EGCG adsorption and release under neutral (pH 7.4, SBF) and acidic (pH 5.0, acetate buffer) conditions. Comprehensive characterization using SEM, EDS, FT-IR, UV-vis spectroscopy, and surface profilometry confirmed uniform zeolite formation, effective EGCG loading, and tunable release profiles. Zinc-containing zeolite exhibited the highest EGCG adsorption but demonstrated cytotoxicity toward hFOB 1.19 osteoblasts. Magnesium-zeolite-coated implants provided controlled EGCG release, were nontoxic, and did not support cell adhesion, making them suitable for temporary internal fixation in the management of orthopedic trauma. Release studies revealed pH-dependent kinetics, with accelerated EGCG release under acidic conditions simulating osteoclast activity. These findings demonstrate the potential of Mg-zeolite-coated titanium implants as functional devices that provide mechanical support, enable localized drug delivery, and promote bone regeneration while minimizing tissue damage during removal.