Investigation of optimized poly(lactic acid)/hydroxyapatite/doxycycline coatings on titanium alloy surfaces

• PLA and PLA_HA coatings prepared using the dip-coating method on Ti6Al4V substrate. • Optimization of parameters based on design of experiments (DoE) • Porosity plays an important role in the corrosion resistance evaluation. • Doxy proved to be a potent inhibitor, both for PLA_D and PLA_HA_D coatings. • Release studies in SBF confirmed the sustained Doxy release during 21 days. The main goal of this research was the preparation and optimization of porous coatings based on poly(lactic acid) (PLA) and poly(lactic acid)-hydroxyapatite (PLA_HA) containing doxycycline (Doxy), to achieve control and sustained Doxy release. The prepared coatings were investigated by different techniques (i.e., SEM-EDX, TG/DTG, contact angle, electrochemical and spectrophotometric methods). The optimization of the coatings prepared by the dip-coating technique focused on the parameters influencing the change in the average pore size and film thickness of the coatings. The results shows that the concentration of the polymer solution had the predominant effect. An increase in immersion time resulted in a decrease in coating thickness. The electrochemical investigation methods showed that the film porosity plays an important role in evaluating the corrosion resistance, as large pores favoured corrosion processes. Moreover, Doxy proved to be a potent inhibitor, both for PLA_D and PLA_HA_D coatings.