Titanium (Ti) coatings deposited by plasma electrolytic oxidation (PEO) exhibit satisfactory biological results. However, the addition of antimicrobial agents such as chemical elements and antibiotics is necessary. Unlike other elements, zinc (Zn) demonstrates good antibacterial capacity and excellent cytocompatibility. The antibiotic demeclocycline (DMC) stands out for presenting, in addition to its bacteriostatic effect, the ability to generate reactive oxygen species when irradiated, being a photosensitizer in antimicrobial photodynamic therapy. Therefore, the aim of this study is to develop a new coating containing calcium, phosphorus and Zn deposited by PEO and coated by a chitosan film for controlled release of DMC, in addition to evaluating its cytocompatibility and antibacterial effect associated or not with light. Initially, the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of the DMC will be determined to establish the initial concentration of the drug to be incorporated into the film. Thus, the following groups will be tested: (I) machined and polished Ti (control); (II) Ti treated with PEO; (III) Ti with PEO and zinc; (IV) Ti with PEO, zinc and chitosan film; (V) Ti with PEO, zinc and chitosan film with DMC and (VI) Ti with PEO, zinc and chitosan film with DMC associated with light. The surface of the discs will be characterized by confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM), energy dispersive spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, profilometry, surface free energy, and photocatalytic activity. The degradation of the chitosan film will be evaluated by SEM. The release of Zn2+ and demeclocycline from the surfaces will be evaluated using inductively coupled plasma analysis and spectrophotometry, respectively. The antimicrobial activity of the surfaces will be evaluated in the absence and presence of light (415 nm; light dose of 10 J/cm2) using a microcosm model. Quantification of colony forming units (CFU/mL), structural analysis of the biofilm by SEM and CLSM, and microbial composition by DNA-DNA checkerboard will be performed. Protein adsorption will be evaluated through bovine serum albumin plasma protein. The cytocompatibility of MC3T3-E1 cells will be evaluated by MTT and fluorescence assay, morphological evaluation by SEM and CLSM, alkaline phosphatase enzyme activity and production of mineralization nodules. Quantitative data will be submitted to descriptive statistics and assumptions check to determine appropriate statistical tests. The significance level will be 0.05.
News published in Agência FAPESP Newsletter about the scholarship: