Effects of ZnO/TiO2 nanoparticle and TiO2 nanotube additions to dense polycrystalline hydroxyapatite bioceramic from bovine bones.

OBJECTIVES: A bovine dense hydroxyapatite ceramic (HA) was produced as new biomaterial, however, the production of a material with consistently high flexural strength remains challenging. The objective of this study was to evaluate the effects of ZnO nanoparticles, TiO2 nanoparticles, and TiO2 nanotubes (1%, 2%, and 5% by weight) on the microstructure and flexural strength of a bovine dense hydroxyapatite ceramic (HA). METHODS: Discs (Ø=12.5mm; thickness=1.3mm) were prepared and subjected to X-ray diffraction (XRD), and observation with a field emission scanning electron microscope (FE-SEM), biaxial flexural strength (BFS) testing, and Vickers hardness (VH) testing. The BFS and VH data were subjected to ANOVA and Tukey post-hoc tests (α=0.05) and Weibull analysis. RESULTS: The XRD showed that the addition of nanomaterials caused the formation of a secondary phase when 5% of the ZnO nanoparticles was used, or when all percentages of the TiO2 nanoparticles/nanotubes were used, and the HA crystallographic planes were maintained. Differences were not observed between the higher BFS values obtained with pure HA and those obtained with the 5% addition of TiO2 nanoparticles. However, the results were different compared with the other groups (α=0.05). The results obtained by Weibull analysis revealed that the 1%, 2%, and 5% addition of TiO2 nanotubes, and the 1% and 2% addition of TiO2 nanoparticles decreased the HA characteristic strength (σ0), while the Weibull modulus (m) increased when 5% of TiO2 nanoparticles, 1% and 2% of ZnO nanoparticles, and 2% of TiO2 nanoparticles were added, but with no statistical difference from the pure HA. The 5% addition of ZnO2 nanoparticles decreased the σ0 without changing m. Moreover, the 5% addition of TiO2 nanoparticles resulted in an m closest to that of pure HA. Regarding the VH results, the blend of HA with 1% and 2% addition of TiO2 nanoparticles exhibited the higher values, which were similar between the different addition ratios (p=0.102). Moreover, the addition of 5% TiO2 nanoparticles resulted in higher value compared with pure HA. SIGNIFICANCE: This study demonstrated that the HA blend with 5% of TiO2 nanoparticles has the greatest potential as a bovine HA dense bioceramic reinforcement.

Resposta in vitro de células pré-osteoblásticas em cerâmica de hidroxiapatita / In vitro evaluation of pre-osteoblastic cells in hydroxyapatite ceramic

Com a evolução do Biomateriais houve melhorias nas opções de tratamentos e atualmente são utilizados em substituição de partes do corpo que foram perdidas e promovem a recuperação de funções biológicas. Dentre eles existem as chamadas Biocerâmicas, que incluem alumina, zircônia e derivadas de fosfato de cálcio. A hidroxiapatita possui composição e estrutura minerais semelhantes à fase mineral óssea e apresenta como propriedades a biocompatibilidade, osteocondutividade e bioatividade. O trabalho avaliou a viabilidade celular em cerâmica de hidroxiapatita experimental de origem bovina em comparação com dois tipos de zircônia comerciais e liga de titânio comercialmente puro, para que futuramente possa ser utilizada como material base para implantes dentários. A avaliação in vitro foi realizada por meio de testes nos quais células pré-osteoblásticas cultivadas de linhagem murina MC3T3-E1 foram colocadas em contato indireto e direto com estes materiais. Para viabilidade celular (n=8) foram feitos testes de ensaio MTT e Cristal Violeta em duplicata e após 24, 48 e 72 horas os níveis de absorbâncias foram analisados por meio de espectrofotometria no leitor de Elisa. Para as analises por microscopia eletrônica de varredura (n=6) as células foram plaqueadas diretamente sobre as superfícies dos discos, fixadas em vapor de tetróxido de ósmio 2% após 24 e 48 horas, seguido da metalização após 48 horas da fixação das células para análise em Microscópio Eletrônico de Varredura. Os resultados para viabilidade indireta foram submetidos ao teste paramétrico ANOVA, seguido de teste de Tukey (p<0,05). Tanto no teste de MTT quanto no Cristal Violeta, de acordo com o grupo controle positivo, todos os grupos apresentaram resultados satisfatórios. A cerâmica de hidroxiapatita não apresentou diferença estatística significante, demonstrando não ser um material citotóxico. Pelas imagens geradas no MEV do teste de viabilidade direta, verificou-se que houve adesão...

With the evolution biomaterials there were improvements in treatment options, and are currently used in replacement body parts that were lost and promote the recovery of biological functions. Among them are the bioceramic which include alumina, zirconia and calcium phosphate derivative. Hydroxyapatite has mineral composition and structure similar to bone mineral phase and can be used as a biomaterial having biocompatibility, osteoconductivity and bioactivity. The study evaluated the cell viability in experimental hydroxyapatite ceramic bovine compared the two types of commercial zirconia and titanium alloy commercially pure, so that in future it can be used as base material for dental implants. In vitro evaluation was carried by means of tests in which the pre-osteoblastic cells MC3T3-E1 murine lineage cultured were placed in indirect and direct contact with these materials. For cell viability (n=8) were carried MTT assay and Crystal Violet tests in duplicate and after 24, 48 and 72 hours the absorbance levels were analyzed by spectrophotometry Elisa reader. For analysis by Scanning Electron Microscope variable pressure (n = 6) cells were plated directly on the discs surfaces, fixed in osmium tetroxide steam 2% after 24 and 48 hours, followed by metallization after 48 of cells fixation. The results for the cell viability were submitted to parametric test ANOVA, followed by Tukey test (p<0.05). Both in the MTT assay as Crystal Violet all groups exhibited satisfactory results absent cytotoxicity. By means of the SEM images produced, it was found that there was adhesion and proliferation of cells on the materials surfaces in the two periods. Therefore, it can be stated that the hydroxyapatite ceramic was presented as a biocompatible material.