Bioconjugated Ag nanoparticles and CdTe nanowires: metamaterials with field-enhanced light absorption.

The hybrid assembly of inorganic and metallic nanomaterials by means of chemical and biological bonding to yield manifold optical and electromagnetic properties has received widespread attention. Currently available highly monodispersed nanomaterials such as semiconductors and noble metals that can be conjugated by ligand–receptor, antigen– antibody reactions, polymer tethering, and DNA hybridization are used as building blocks for 2D or 3D superstructures in which new collective properties of these artificial assemblies have been obtained. They represent a large class of newmaterials (i.e., metamaterials) in which the properties are determined not only by classical atomic composition, but also by nanoscale organization of structural components. Recently, metamaterials based on metallic composites have received special attention as these are expected to display negative values for permittivity and refractive index. This property should lead to a multitude of unique optical effects. Many of these effects are related to surface plasmons on Au or Ag nanoparticles (NPs), which generate exceptionally high localized electromagnetic fields, and have been exploited in surface-enhanced Raman spectroscopy and some optoelectronic devices. 22] Metamaterials from semiconductors and their combinations with metals can also produce optical effects that are useful for development of advanced sensing and imaging technologies. Recently, we