Showing papers by "Sara E. Skrabalak published in 2013"

Seeding Bimetallic Nanostructures as a New Class of Plasmonic Colloids

Abstract: Colloidal plasmonics is a rapidly developing field, with applications of metal nanoparticles that range from biosensing to photocatalysis. Historically, Au- or Ag-only nanoparticles have been investigated for these uses. However, there is emerging interest in multifunctional plasmonic colloids as well as a desire to expand the light scattering and absorption properties of Au or Ag nanoparticles. Both of these goals can be achieved by incorporating a second metal. In this Perspective, recent advances in the synthesis and application of Au–Ag and Au–Pd nanostructures are discussed. The highlighted nanostructures were synthesized through the seed-mediated method, an approach that provides for structurally complex nanoarchitectures while maintaining sample homogeneity. Overall, these architecturally controlled bimetallic nanostructures are representative of a new class of plasmonic colloids in which composition and structure can be manipulated to achieve unique optical properties and functionality.

Core values: elucidating the role of seed structure in the synthesis of symmetrically branched nanocrystals.

Abstract: Branched metal nanoparticles often display unique physicochemical properties on account of their structures; however, most examples are asymmetric, with branches randomly distributed from the cores of the nanoparticles. This asymmetry can give rise to variable properties between samples. Here, we report the synthesis of symmetrically branched Au/Pd nanocrystals including five-branched pentapods with D3h symmetry, 24-branched nanocrystals with Oh symmetry, 12-branched nanocrystals with Td symmetry, and eight-branched octopods and bowties with Oh and D4h symmetry, respectively. These structures are achieved by seed-mediated co-reduction wherein the shapes of the seeds direct the number and symmetry patterns of the branches. Compositional boundaries exist at the interfaces between the seed and overgrowth metals to provide visualization via advanced electron microscopy of the relationships between seed structure and the symmetry of branched nanocrystals. Significantly, seed structure plays a definitive role i...

Sub 2-μm macroporous silica particles derivatized for enhanced lectin affinity enrichment of glycoproteins.

Abstract: A new, mechanically stable silica microparticle with macrosized internal pores (1.6 μm particles with 100 nm pores) has been developed for chromatography. The particles are characterized by an exte...

Aerosol-assisted synthesis and assembly of nanoscale building blocks

Abstract: Aerosol methods, including spray drying and spray pyrolysis, represent industrial scale routes to materials on account of their continuous nature. Recently, these methods have been used to prepare size-, shape- and architecturally controlled nanostructures for a range of inorganic materials. In this Feature Article, a brief overview of traditional aerosol methods is provided. Then, the new chemical methods that have been integrated into aerosol techniques to achieve high quality nanomaterials are highlighted. Given that the properties of nanomaterials are dependent on their structural features, these synthetic advances help to address the critical need for new nanomanufacturing routes to materials.

Spatial and Temporal Confinement of Salt Fluxes for the Shape-Controlled Synthesis of Fe2O3 Nanocrystals

Abstract: Here, molten salt syntheses (MSS) are coupled with ultrasonic spray pyrolysis to yield single-crystalline Fe2O3 nano- and microparticles with controlled shapes and phases. It was previously demonstrated that aerosol-assisted MSS can produce single-crystalline nanoplates. Now, by selecting different molten salt flux components, various crystalline phases and particle shapes are accessed via the dissolution of Fe2O3 colloids, followed by precipitation of the iron oxide products from molten alkali carbonates that are spatially and temporally confined in the aerosol phase. This confinement limits crystal growth to the nanoscale and provides access to products at different stages of supersaturation. The resulting powders consist of hexagonal nanoplates (α- or γ-Fe2O3), rhombohedra (α-Fe2O3), or octahedra (LiFe5O8) depending on the selected molten salt flux. Significantly, this synthetic approach represents a continuous and potentially general route to the generation of shape- and phase-controlled nano- and mic...

Manipulating the kinetics of seeded growth for edge-selective metal deposition and the formation of concave au nanocrystals.

Abstract: By manipulating the kinetics of seeded growth through judicious control of reaction conditions, edge-selective metal deposition can be achieved to synthesize new Au nanostructures with face-centered concavities, referred to herein as Au overgrown trisoctahedra. These nanostructures display higher sensitivity to changes in refractive index compared to both Au traditional trisoctahedra and the Au nanocube seeds from which they are grown. Often, concave nanostructures are achieved by selective etching processes or corner-selective overgrowth and adopt a stellated profile rather than a profile with face-centered concavities. The presented results illustrate another strategy toward concave nanostructures and can facilitate the synthesis of new concave nanostructures for applications in catalysis and chemical sensing.

Application of macroporous silica synthesized by a salt-templated aerosol method for chromatography

Abstract: The present invention discloses a silica particle having a diameter less than or equal to 2 μη, wherein the particle is spherical and comprises interconnected pores having a diameter in the range from 50 nm to 300 nm. The silica particle is preferably produced by spray pyrolysis (=spray drying) of a silica colloid. In the production process, porosity is introduced by means of an inorganic salt, such as NaCl, KCI, LiCl, NaNO3 or Ll NO3, which serves as a pore template. The silica particle may further be functionalized with proteins, peptides, nucleic acids, polysaccharides and proteoglycans, preferably concanavalin A or avidin. The present invention further discloses the use of the silica particle in chromatography, in particular in affinity chromatography.