RESUMEN
Cancer is one of the deadliest diseases worldwide and has been responsible for millions of deaths. However, developing a satisfactory smart multifunctional material combining different strategies to kill cancer cells poses a challenge. This work aims at filling this gap by developing a composite material for cancer treatment through hyperthermia and drug release. With this purpose, magnetic nanoparticles were coated with a polymer matrix consisting of poly (L-co-D,L lactic acid-co-trimethylene carbonate) and a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer. High-resolution transmission electron microscopy and selected area electron diffraction confirmed magnetite to be the only iron oxide in the sample. Cytotoxicity and heat release assays on the hybrid nanoparticles were performed here for the first time. The heat induction results indicate that these new magnetic hybrid nanoparticles are capable of increasing the temperature by more than 5 °C, the minimal temperature rise required for being effectively used in hyperthermia treatments. The biocompatibility assays conducted under different concentrations, in the presence and in the absence of an external alternating current magnetic field, did not reveal any cytotoxicity. Therefore, the overall results indicate that the investigated hybrid nanoparticles have a great potential to be used as carrier systems for cancer treatment by hyperthermia.
Asunto(s)
Calefacción , Hipertermia Inducida , Humanos , Hipertermia , ElectricidadRESUMEN
Objetivo: revisar as semelhanças e diferenças entre os implantes dentários osseointegráveis e os implantes ortopédicos. Material e métodos: apesar da escassez de dados, foram construídos quatro tópicos: 1) materiais dos implantes osseointegráveis e ortopédicos; 2) técnicas cirúrgicas na Odontologia e na Ortopedia; 3) possíveis causas e efeitos do aquecimento; e 4) análise do insucesso dos implantes nas duas áreas. Resultados: 1) nenhum dos biomateriais metálicos usados na Ortopedia apresenta osseointegração conforme o conceito atualmente usado na Odontologia e, sob alto carregamento, estas ligas estão submetidas ao stress shielding em função do seu módulo de elasticidade ser muito acima do osso; 2) na Implantodontia, a estabilidade primária é fundamental e os procedimentos são mais delicados, enquanto na Ortopedia os implantes são cimentados (estabilizados) e os procedimentos ortopédicos são mais agressivos, estando entre os maiores índices de perdas advindas de complicações pós-cirúrgicas; 3) as condições de realização da cirurgia para inserção de implantes ortopédicos são mais críticas em relação aos dentários, devido ao maior volume de osso que é removido, maiores dimensões da prótese, menor vascularização do local e ausência de irrigação do meio durante a cirurgia, com temperaturas médias (70oC) acima do que se observa na Implantodontia odontológica (43oC); 4) a propensão ao insucesso nos implantes ortopédicos parece maior pela chance de carregamento 3-5 vezes maior em áreas corporais (quadril e joelho) que sustentam o peso do corpo. Conclusão: melhorias contínuas nos materiais, procedimentos e treinamento fornecerão taxa menor de reposição de implantes dentários e, especialmente, dos implantes ortopédicos.
Objective: to review the similarities and differences between osseointegrated dental and orthopedic implants. Material and methods: besides data paucity, four topics were created: 1) materials for osseointegrated and orthopedic implants; 2) surgical techniques in Dentistry and Orthopedics; 3) possible causes and effects of heating; and 4) failures analyses in both areas. Results: 1) none of the metallic biomaterials for Orthopedics present osseointegration according to the concept developed for dentistry and, under high loading, alloys are subjected to stress shielding due to their elastic moduli being higher than the bone; 2) for implant dentistry, primary stability is fundamental and the procedures are more delicate, whereas in Orthopedics the implants are cemented (stabilized) and the procedures have a more aggressive nature, within the highest levels of post-surgical complications; 3) surgical conditions for Orthopedics are more critical than in the dental field, due to a greater bone volume, prosthesis size, less local vascularization and lack of irrigation, with mean temperatures (70oC) well-above compared to the implant dentistry (43oC); 4) the failure of orthopedic implants seems higher due to the 3-5 times chance of loading at corporal bearing structures (hips and knees). Conclusion: continuous improvement on materials, procedures, and training will provide less replacement rates for dental implants and specially for orthopedic devices.
