Efeitos biológicos da funcionalização de superfícies de TiO2 com Alendronato de Sódio e Albumina (BSA)
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2020-03-18
Autores
Albano, Carolina Simão
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Universidade Estadual Paulista (Unesp)
Resumo
O dióxido de titânio (TiO2) tem sido utilizado como modificador de superfície de implantes, possibilitando um aperfeiçoamento na resistência à tribocorrosão do material e aumento da bioatividade dos óxidos, apresentando resultados favoráveis quando em contato com o tecido vivo. Apesar da biocompatibilidade deste óxido ser reconhecida, ainda existem muitos aspectos inexplorados sobre os mecanismos de imobilização entre as proteínas e a superfície do material que induzem à osseointegração do implante. No entanto, entre diferentes estratégias, a superfície de TiO2 pode ser prontamente funcionalizada através dos grupos hidroxila com grupos bifuncionais, tais como bisfosfonatos e proteínas, os quais podem melhorar a osseointegração do implante. No presente estudo o bisfosfonato em questão é o alendronato de sódio, um fármaco utilizado no tratamento de doenças associadas ao aumento da reabsorção óssea, como a osteoporose. A albumina é a proteína de interesse que se associa aos processos biológicos iniciais após a incorporação do implante. A fim de analisar a morfologia e a rugosidade superficial, foram realizadas técnicas de caracterização por Microscopia Eletrônica de Varredura e Microscopia Óptica Confocal, respectivamente; além do ângulo de contato que avaliou a molhabilidade das superfícies. As superfícies modificadas com TiO2 foram analisadas por Difração de Raios X, a qual indicou a formação da fase cristalina rutilo. Além disso, após a imobilização de alendronato e BSA, a técnica de XPS indicou uma funcionalização eficiente da superfície. Quando a superfície de um material com aplicações biomédicas é modificada, alguns ensaios in vitro são necessários para a avaliação da toxicidade celular, permitindo averiguar os possíveis efeitos durante a adesão e a proliferação de células quando colocadas em contato direto e indireto com o material. A biocompatibilidade das superfícies funcionalizadas foi analisada através do comportamento de adesão de pré-osteoblastos e fibroblastos nas amostras. Os resultados mostraram uma melhora significativa em relação à adesão e viabilidade celular. Além disso, o remodelamento da matriz extracelular é um pré-requisito importante para os estágios iniciais da adesão celular aos biomateriais, que foram testados pela avaliação das atividades enzimáticas das metaloproteinases da matriz (MMPs) e das expressões gênicas. Por fim, os dados expressaram um panorama da diferenciação osteoblástica como um comportamento adaptativo quando as células entraram em contato com as superfícies biofuncionalizadas por 24 horas. De maneira geral, os resultados mostraram um interessante desempenho osteogênico das células que responderam às superfícies com alendronato de sódio e BSA, no entanto, análises in vivo são necessárias para melhor considerar essas superfícies em ensaios clínicos na área biomédica.
Titanium dioxide (TiO2) has been used as an implant surface modifier, enabling an improvement in the material's tribocorrosion resistance and increased oxide bioactivity, showing favorable results when in contact with living tissue. Although the biocompatibility of this oxide is recognized, there are still many unexplored aspects about the mechanisms of immobilization between proteins and material surface that induce implant osseointegration. However, among different strategies, the TiO2 surface can be readily functionalized through hydroxyl groups with bifunctional groups, such as bisphosphonates and proteins, which can improve implant osseointegration. In the present study the bisphosphonate in question is sodium alendronate, a drug used to treat diseases associated with increased bone resorption, such as osteoporosis. Albumin is the protein of interest that is associated with early biological processes following implant incorporation. In order to analyze morphology and surface roughness, Scanning Electron Microscopy and Confocal Optical Microscopy characterization techniques were performed, respectively; besides the contact angle that evaluated the wettability of the surfaces. TiO2-modified surfaces were analyzed by X-ray Diffraction, which indicated the formation of rutile crystalline phase. In addition, after immobilization of alendronate and BSA, the XPS technique indicated efficient surface functionalization. When the surface of a material with biomedical applications is modified, some in vitro assays are required to assess cell toxicity, allowing to investigate the possible effects during cell adhesion and proliferation when placed in direct and indirect contact with the material. The biocompatibility of functionalized surfaces was analyzed by the adhesion behavior of pre-osteoblasts and fibroblasts in the samples. The results showed a significant improvement regarding adhesion and cell viability. In addition, extracellular matrix remodeling is an important prerequisite for the early stages of cell adhesion to biomaterials, which were tested by evaluating the enzymatic activities of matrix metalloproteinases (MMPs) activities and gene expression. Finally, the data expressed an overview of osteoblastic differentiation as an adaptive behavior when cells came into contact with biofunctionalized surfaces for 24 hours. Overall, the results showed an interesting osteogenic performance of cells that responded to surfaces with sodium alendronate and BSA, however, in vivo analysis is needed to better consider these surfaces in clinical trials in the biomedical field.
Titanium dioxide (TiO2) has been used as an implant surface modifier, enabling an improvement in the material's tribocorrosion resistance and increased oxide bioactivity, showing favorable results when in contact with living tissue. Although the biocompatibility of this oxide is recognized, there are still many unexplored aspects about the mechanisms of immobilization between proteins and material surface that induce implant osseointegration. However, among different strategies, the TiO2 surface can be readily functionalized through hydroxyl groups with bifunctional groups, such as bisphosphonates and proteins, which can improve implant osseointegration. In the present study the bisphosphonate in question is sodium alendronate, a drug used to treat diseases associated with increased bone resorption, such as osteoporosis. Albumin is the protein of interest that is associated with early biological processes following implant incorporation. In order to analyze morphology and surface roughness, Scanning Electron Microscopy and Confocal Optical Microscopy characterization techniques were performed, respectively; besides the contact angle that evaluated the wettability of the surfaces. TiO2-modified surfaces were analyzed by X-ray Diffraction, which indicated the formation of rutile crystalline phase. In addition, after immobilization of alendronate and BSA, the XPS technique indicated efficient surface functionalization. When the surface of a material with biomedical applications is modified, some in vitro assays are required to assess cell toxicity, allowing to investigate the possible effects during cell adhesion and proliferation when placed in direct and indirect contact with the material. The biocompatibility of functionalized surfaces was analyzed by the adhesion behavior of pre-osteoblasts and fibroblasts in the samples. The results showed a significant improvement regarding adhesion and cell viability. In addition, extracellular matrix remodeling is an important prerequisite for the early stages of cell adhesion to biomaterials, which were tested by evaluating the enzymatic activities of matrix metalloproteinases (MMPs) activities and gene expression. Finally, the data expressed an overview of osteoblastic differentiation as an adaptive behavior when cells came into contact with biofunctionalized surfaces for 24 hours. Overall, the results showed an interesting osteogenic performance of cells that responded to surfaces with sodium alendronate and BSA, however, in vivo analysis is needed to better consider these surfaces in clinical trials in the biomedical field.
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Palavras-chave
Biomaterial, Dióxido de titânio, Superfícies, Biocompatibilidade, Osseointegração, Biomaterial, Titanium dioxide, Surfaces, Biocompatibility, Osseointegration