RESUMO
A submicrometer-sized pH sensor based on biotin-fluorescein-functionalized multiwalled BN nanotubes with anchored Ag nanoparticles is designed. Intrinsic pH-dependent photoluminescence and Raman signals in attached fluorescein molecules enhanced by Ag nanoparticles allow this novel nanohybrid to perform as a practical pH sensor. It is able to work in a submicrometer-sized space. For example, the sensor may determine the environmental pH of sub-units in living cells where a traditional optical fiber sensor fails because of spatial limitations.
Assuntos
Técnicas Biossensoriais/métodos , Compostos de Boro/química , Nanotecnologia/métodos , Nanotubos/química , Concentração de Íons de Hidrogênio , Medições Luminescentes/métodos , Microscopia Eletrônica de Varredura , Nanopartículas/química , Nanopartículas/ultraestrutura , Nanotubos/ultraestrutura , Espectrometria de FluorescênciaRESUMO
A comprehensive understanding of the design, synthesis, characterization, and properties of boron carbonitride nanotubes (BCN) is presented in this review. Distinctive structural and electronic properties are revealed in theoretical studies of the BCN nanotubes and compared with the properties of carbon nanotubes. In the experimental studies, BCN nanotubes have been synthesized by various techniques. For different purposes, controllable growth processes have been used to fabricate BCN nanotubes with novel structures, such as nanojunctions and filled nanotubes. Some interesting phenomena originating from the substitution of B and N atoms, such as the phase segregation, are considered theoretically and experimentally. Mainly the physical properties--field electron emission and photoluminescence--are discussed, which turn out to have potential applications in the industry.
Assuntos
Compostos de Boro/química , Compostos de Boro/isolamento & purificação , Cristalização/métodos , Luminescência , Nanotecnologia/instrumentação , Nanotecnologia/métodos , Nanotubos/química , Nanotubos/ultraestrutura , Compostos de Boro/síntese química , Condutividade Elétrica , Eletroquímica/métodos , Campos Eletromagnéticos , Teste de Materiais , Microscopia Eletrônica de Varredura , Conformação Molecular , Fotoquímica/instrumentação , Fotoquímica/métodos , Propriedades de SuperfícieRESUMO
Large-scale highly aligned boron carbonitride (BCN) nanofibers with controllable orientations and chemical compositions were synthesized directly on nickel substrates from a gas mixture of N2, H2, CH4, and B2H6 by plasma-enhanced hot filament chemical vapor deposition. The morphology of the BCN nanofibers was examined by scanning electron microscopy, the microstructures were studied by high-resolution transmission electron microscopy, and the bonding states as well as chemical compositions were determined by electron energy loss spectroscopy. To our knowledge, this is the first report on the photoluminescent properties of BCN nanofibers that shows that they are interesting blue- and violet-light-emitting materials with tunable wavelengths. Further studies on field electron emission suggest that BCN nanofibers are also promising candidates for field emission sources.
