Metal Nanoshells

Abstract

Metal nanoshells are a new class of nanoparticles with highly tunable optical properties. Metal nanoshells consist of a dielectric core nanoparticle such as silica surrounded by an ultrathin metal shell, often composed of gold for biomedical applications. Depending on the size and composition of each layer of the nanoshell, particles can be designed to either absorb or scatter light over much of the visible and infrared regions of the electromagnetic spectrum, including the near infrared region where penetration of light through tissue is maximal. These particles are also effective substrates for surface-enhanced Raman scattering (SERS) and are easily conjugated to antibodies and other biomolecules. One can envision a myriad of potential applications of such tunable particles. Several potential biomedical applications are under development, including immunoassays, modulated drug delivery, photothermal cancer therapy, and imaging contrast agents.

Controllable Cobalt Oxide/Au Hierarchically Nanostructured Electrode for Nonenzymatic Glucose Sensing

“…Nanoshells are another type of metal nanostructures with interesting optical properties useful for various applications [59][60][61][62][63]. These structures, which are typically made of spherical silica cores surrounded by a layer of noble metal aggregates, have variation in size, shape and surface morphology due to the random nature of aggregation [64,65].…”

“…This promotes both optimal cell penetration and bioclearance [70,71,73]. Additionally, nanomaterials must be stable to photodegradation, biocompatible and capable of conjugating easily to biomolecules [53,60,74]. However, most commonly used structures lack one or more of these requirements, and their use in many bio-applications still needs to be optimized.…”

“…HGNs are also biocompatible, stable to photodegradation and can be easily functionalized for use in bio-targeting and biodelivery [53,60,[78][79][80]. These particles also possess large surface to volume (S/V) ratios, tunable plasmon resonance, pinholes that act as hot spots to further intensify EM surface energy and, as hollow structures, are known to be more sensitive to the refractive index of their surroundings than their solid counterparts [15,66,[81][82][83][84].…”

“…In addition to their small size, spherical shape, biocompatibility, and lack of susceptibility to photobleaching, their extinction peaks can be easily tuned to the NIR [60,78,79,221]. Additionally, the enhanced near field energy associated with their surface plasmon resonance and thin shells, which produce high absorption cross-sections, makes them ideal nanostructures for PTA.…”

Environmentally responsive polymeric "intelligent" materials: the ideal components of non-mechanical valves that control flow in microfluidic systems

“…The transverse mode resonance resembles the observed peak for spheres, but the longitudinal mode is considerably red-shifted and depends strongly on the difference in length compared to width. The absorption spectrum can be shifted from the blue to the red by forming elongated wires, tubes, belts, and other more sophisticated structures (stars, rings, cubes, nanoshells and onion-like structures) that incorporate different metals (Aizpurua et al, 2003;Lu et al, 2004;Chen et al, 2005;Halas, 2005;Hirsch et al, 2006). All these shapes have been synthesized to move the absorption peaks across the absorption spectrum and design sensors and molecular labels.…”