CYTOTOXICITY EVALUATION OF SILOXANE COATED TITANIUM OBTAINED BY SOL-GEL METHOD AFTER ANODIZATION IN CONVENTIONAL ACIDS OR Psidium guajava EXTRACT

Resumo

INTRODUCTION: Titanium is widely used in implants; however, the release of metal ions can lead to cytotoxicity. Anodization produces a protective oxide layer that mitigates these effects. Moreover, this surface can be further enhanced with siloxane-based coatings, which offer stability and corrosion resistance. OBJECTIVE: This study evaluates the cytotoxicity of a siloxane coating obtained via the Sol-Gel method as an alternative strategy to improve the titanium surface after anodization. For this purpose, 1×1 cm titanium plates were subjected to three anodization electrolytes: phosphoric acid (H₃PO₄), a combination of phosphoric and hydrofluoric acids (H₃PO₄ + HF) and Psidium guajava leaves extract. Each group was analyzed with and without the application of the siloxane coating to assess the impact of the coating on cell viability. MATERIALS AND METHODS: The cytotoxicity of the siloxane-based coating was evaluated using human osteosarcoma cells (Saos-2) cultured in DMEM supplemented with 10% FBS. The assay was performed in microplates using confluent monolayers of cells incubated with extraction medium (EM) for 24 hours at 37°C and 5% CO₂. The EM was obtained by incubating titanium plates in culture medium for 24 hours at 37°C. As a negative control, only DMEM with 10% FBS was used. Cell viability was assessed by the colorimetric Neutral Red uptake and the MTT reduction assays. Statistical analysis was performed using ANOVA followed by Tukey’s post hoc test (p ≤ 0.05). RESULTS AND CONCLUSION: For MTT assay, the coating of anodized titanium with siloxane prevented the increase in mitochondrial activity typically observed after anodization with acidic electrolytes, reducing this increase by 38% for H₃PO₄ and by 30% for H₃PO₄ + HF. For NRU assay, no difference was observed for these samples. The siloxane layer probably minimizes the leaching of species capable of interfering with mitochondria’s oxidative status. Samples from Psidium guajava electrolyte didn’t show alterations for either assay. Taking together, our results demonstrated that the anodized plates—regardless of the electrolyte used—and the siloxane coating maintained 100% cell viability, comparable to the negative control. In conclusion, the siloxane coating does not cause cytotoxicity and may be a promising strategy for surface preservation.