Physico-chemical and biological evaluation of doxycycline loaded into hybrid oxide-polymer layer on Ti-Mo alloy

Oxide-polymer coatings were formed on the surface of the vanadium-free Ti–15Mo titanium alloy.The Ti alloy surface was modified by the plasma electrolytic oxidation process,and then,the polymer layer of a poly(D,Llactide-co-glycolide)with doxycycline was formed.The polymer evenly covered the porous oxide layer and filled some of the pores.However,the microstructure of the polymer surface was completely different from that of the PEO layer.The surface morphology,roughness and microstructure of the polymer layer were examined by scanning electron microscopy(SEM)and a confocal microscope.The results confirmed the effectiveness of polymer and doxycycline deposition in their stable chemical forms.The drug analysis was performed by highperformance liquid chromatography.The 1H NMR technique was used to monitor the course of hydrolytic degradation of PLGA.It was shown that the PLGA layer is hydrolysed within a few weeks,and the polyglycolidyl part of the copolymer is hydrolysed to glycolic acid as first and much faster than the polylactide one to lactic acid.This paper presents influence of different microstructures on the biological properties of modified titanium alloys.Cytocompatibility and bacterial adhesion tests were evaluated using osteoblast-like MG-63 cells and using the reference S.aureus and S.epidermidis strains.The results showed that the optimum concentration of doxycycline was found to inhibit the growth of the bacteria and that the layer is still cytocompatible.

Antibacterial and cytocompatible coatings based on poly(adipic anhydride) for a Ti alloy surface

This paper describes a formation of hybrid coatings on a Ti-2Ta-3Zr-36Nb surface.This is accomplished by plasma electrolytic oxidation and a dip-coating technique with poly(adipic anhydride)((C6H8O3)n)that is loaded with drugs:amoxicillin(C16H19N3O5S),cefazolin(C14H14N8O4S3)or vancomycin(C66H75Cl2N9O24·xHCl).The characteristic microstructure of the polymer was evaluated using scanning electron microscopy and confocal microscopy.Depending on the surface treatment,the surface roughness varied(between 1.53μm and 2.06μm),and the wettability was change with the over of time.X-ray photoelectron spectroscopy analysis showed that the oxide layer did not affect the polymer layer or loaded drugs.However,the drugs lose their stability in a phosphate-buffered saline solution after 6.5 h of exposure,and its decrease was greater than 7%(HPLC analysis).The stability,drug release and concentration of the drug loaded into the material were precisely analyzed by high-performance liquid chromatography.The results correlated with the degradation of the polymer in which the addition of drugs caused the percent of degraded polymer to be between 35.5%and 49.4%after 1 h of material immersion,depending on the mass of the loaded drug and various biological responses that were obtained.However,all of the coatings were cytocompatible with MG-63 osteoblast-like cells.The drug concentrations released from the coatings were sufficient to inhibit adhesion of reference and clinical bacterial strains(S.aureus).The coatings with amoxicillin showed the best results in the bacterial inhibition zone,whereas coatings with cefazolin inhibited adhesion of the above bacteria on the surface.