Electrodeposition of Polypyrrole coatings on treated titanium surfaces by plasma electrolytic oxidation for dental implants application

Author(s)

Maria Helena Rossy Borges

• Document type: Master's Dissertation
• Press: Piracicaba, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Odontologia de Piracicaba
• Defense date: 2022-02-24

Examining board members

Valentim Adelino Ricardo Barão; Isabella da Silva Vieira Marques; Heloisa Navarro Pantaroto

• Advisor: Valentim Adelino Ricardo Barão

Abstract

Conductive polymers have been pointed as a promising coating strategy for biomaterials. Polypyrole (PPy) is a conductive polymer that presents adequate physics and electrochemical properties when deposited onto titanium (Ti) surfaces. However, PPy coatings have limitations such as low adhesion to metals and poor mechanical resistance. Therefore, this study developed a coating with plasma electrolytic oxidation (PEO) and the subsequent deposition of PPy film on the Ti surfaces and investigated the effect of PEO surface on the adhesiveness, physical-chemical, mechanical, microbiological, biological and corrosion resistance properties of PPy. Thus, commercially pure titanium (cpTi) discs were used with different treatments: (1) machined; (2) PEO; (3) machined and PPy-coated; (4) PEO and PPy-coated. Discs surfaces were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Vickers microhardness, profilometry, and 3D confocal laser scanning microscopy (CLSM). The conductivity of the film was evaluated by applying a continuous potential and using an electrical circuit. The friction coefficient of surfaces was evaluated in a tribological system and the morphology of the wear scars was investigated by SEM. In addition, the nanoindentation test and the evaluation of the PPy film adhesiveness were also carried out. Electrochemical tests were conducted with body fluid solution (SBF) (pH 7.4). The albumin and Fetal bovine serum (FBS) proteins interaction with the surfaces was measured by the bicinchoninic acid method. For the microbiological assay (microcosm model and Streptococcus Sanguinis), the biofilm (24 h) formation onto surfaces was evaluated by colony forming units (CFU/mL), the biofilm structure was analyzed by SEM. The cytotoxicity of surfaces for MC3T3-E1 pre-osteoblastic and Human Gingival Fibroblast (HGF) cells was investigated using the MTT assay. Furthermore, SEM was used to analyze the morphology of cells onto the surfaces. The results of this study demonstrated that PEO+PPy increased corrosion resistance, adhesive and mechanical strength of Ti when compared to machined Ti. Furthermore, the PPy film favored proteins adsorption, calcium phosphate growth, and demonstrated cell biocompatibility. Also, no increase in bacterial proliferation was identified on surfaces treated with PPy film. In general, we successfully developed a strategy to deposit tattoo-inspired PPy thin film onto the PEO surface by electrodeposition process, which may be favorable in promoting greater stability and longevity for biomedical implants (AU)

• FAPESP's process: 20/07087-8 - Electrodeposition of polypyrrole coatings on anodized titanium surfaces for dental implants application
• Grantee: Maria Helena Rossy Borges
• Support Opportunities: Scholarships in Brazil - Master