Creation, Characterization and Corrosion Behavior of Antibacterial Double‐Layer PLGA/CaP Coatings Impregnated With Vancomycin on Titanium Implants

ABSTRACT Creation of vancomycin (Vanc)‐loaded bone implants as drug delivery systems for the treatment of bone defects complicated by infectious pathology is extremely important. Topcoat PLGA at concentrations of 5, 8, and 10 wt% was applied to Vanc‐loaded CaP coating deposited by hybrid ultrasound‐assisted micro‐arc oxidation on pure Ti and subsequently evaluated. PLGA coating was placed on the surface of CaP undercoat impregnated with Vanc, which had a porosity of 28%–37%, thickness of 53 μm, and roughness of 3.3 μm. Dense homogeneous PLGA finish resulted in closure of CaP surface pores and cracks, a decrease in porosity to 4%–14%, a reduction in roughness to 2.3 μm and an increase in thickness to 70.4 μm. PLGA‐free CaP coatings exhibited excellent hydrophilicity and high surface free energy (SFE) of 73.8 mJ·m −2 . Applying topcoat PLGA to the Vanc‐loaded CaP coating hydrophobized the surface, reducing SFE to 21.3–50.7 mJ·m −2 . Double‐layer PLGA/CaP coatings exhibited higher impedance modulus (| Z | = 1.54–2.04 × 10 7 Ω·cm 2 ) and more stable electrochemical response ( R p = 2.08 × 10 7 −2.29 × 10 8 Ω·cm 2 ) compared to CaP coatings (| Z | = 1.23 × 10 5 Ω·cm 2 ; R p = 1.75 × 10 5 Ω·cm 2 ), indicating improved corrosion resistance provided by the polymeric top coating. Bulk stability provided by the PLGA/CaP coating, characterized by nonpolar ester backbone (methyl groups) of PLA, is integrated with a functional hydroxyl and phosphate groups of CaP. Vanc‐loaded double‐layer PLGA/CaP coatings on Ti implants have demonstrated complex hierarchical morphology, amorphous phase structure and excellent electrochemical stability, which can ensure delayed drug release and long‐term antibacterial efficacy.