RESUMEN
In this review we provide an overview of the recent progress in designing composite polymer capsules based on the Layer-by-Layer (LbL) technology demonstrated so far in material science, focusing on their potential applications in medicine, drug delivery and catalysis. The benefits and limits of current systems are discussed and the perspectives on emerging strategies for designing novel classes of therapeutic vehicles are highlighted.
Asunto(s)
Cápsulas/química , Disciplinas de las Ciencias Biológicas , Catálisis , Sistemas de Liberación de Medicamentos , Preparaciones Farmacéuticas/administración & dosificación , Polímeros/químicaRESUMEN
We report a quantitative analysis of the forces acting on optically trapped single gold nanorods. Individual nanorods with diameters between 8 and 44 nm and aspect ratios between 1.7 and 5.6 were stably trapped in three dimensions using a laser wavelength exceeding their plasmon resonance wavelengths. The interaction between the electromagnetic field of an optical trap and a single gold nanorod correlated with particle polarizability, which is a function of both particle volume and aspect ratio.
RESUMEN
We study the wavelength and polarization dependent plasmon resonances of single silver and gold nanorods, triangles, cubes, and dimers with a novel single particle spectroscopy method (RotPOL). In RotPOL, a rotating wedge-shaped polarizer encodes the full polarization information of each particle within one image. This reveals the symmetry of the particles and their plasmon modes, allows analyzing inhomogeneous samples and the monitoring of particle shape changes during growth in situ.
Asunto(s)
Oro/química , Nanopartículas del Metal/química , Plata/química , Anisotropía , Nanopartículas del Metal/ultraestructura , Microscopía Electrónica de TransmisiónRESUMEN
Silver coating gold nanorods reduces the ensemble plasmon line width by changing the relation connecting particle shape and plasmon resonance wavelength. This change, we term "plasmonic focusing", leads to less variation of resonance wavelengths for the same particle size distribution. We also find smaller single particle linewidth comparing resonances at the same wavelength but show that this does not contribute to the ensemble linewidth narrowing.
Asunto(s)
Cristalización/métodos , Oro/química , Nanotecnología/métodos , Nanotubos/química , Nanotubos/ultraestructura , Plata/química , Resonancia por Plasmón de Superficie/métodos , Sustancias Macromoleculares/química , Ensayo de Materiales , Conformación Molecular , Tamaño de la Partícula , Propiedades de SuperficieRESUMEN
We demonstrate the separation of gold and silver nanoparticles according to their size and shape by agarose gel electrophoresis after coating them with a charged polymer layer. The separation is monitored optically using the size- and shape-dependent plasmon resonance of noble metal particles and confirmed by transmission electron microscopy (TEM). Electrophoretic mobilities are quantitatively explained by a model based on the Henry formula, providing a theoretical framework for predicting gel mobilities of polymer coated nanoparticles.
Asunto(s)
Ensayo Cometa/métodos , Oro/química , Oro/aislamiento & purificación , Modelos Químicos , Nanoestructuras/química , Plata/química , Plata/aislamiento & purificación , Simulación por Computador , Nanotecnología/métodos , Tamaño de la PartículaRESUMEN
We present a general strategy to stabilize gold nanorod suspensions with mono- and bifunctional polyethylene glycol (PEG) and to attach a controlled number of nanoparticles or biomolecules. Characterization by gel electrophoresis, transmission electron microscopy (TEM), and optical dark-field microscopy show the specific binding of functionalized nanorods to their target while avoiding nonspecific binding to substrates, matrices, and other particles. Such nanorods are well suited for self-assembly of nanostructures and single-molecule labeling.
