RESUMEN
We develop approaches to hold fluorescent silver clusters composed of only 10-20 atoms in nanoscale proximity, while retaining the individual structure of each cluster. This is accomplished using DNA clamp assemblies that incorporate a 10 atom silver cluster and a 15 or 16 atom silver cluster. Thermally modulated fluorescence resonance energy transfer (FRET) verifies assembly formation. Comparison to Förster theory, using measured spectral overlaps, indicates that the DNA clamps hold clusters within roughly 5 to 6 nm separations, in the range of the finest resolutions achievable on DNA scaffolds. The absence of spectral shifts in dual-cluster FRET pairs, relative to the individual clusters, shows that select few-atom silver clusters of different sizes are sufficiently stable to retain structural integrity within a single nanoscale DNA construct. The spectral stability of the cluster persists in a FRET pair with an organic dye molecule, in contrast to the blue-shifted emission of the dye.
Asunto(s)
Transferencia Resonante de Energía de Fluorescencia , Nanotecnología/métodos , Plata/química , Secuencia de Bases , Colorantes/química , ADN/química , Nanopartículas del Metal/química , Datos de Secuencia Molecular , Distribución Normal , Oligonucleótidos/química , Rodaminas/química , Espectrometría de Fluorescencia , TemperaturaRESUMEN
Fluorescent DNA-stabilized silver nanoclusters contain both cationic and neutral silver atoms. The absorbance spectra of compositionally pure solutions follow the trend expected for rod-shaped silver clusters, consistent with the polarized emission measured from individual nanoclusters. The data suggest a rod-like assembly of silver atoms, with silver cations mediating attachment to the bases.
Asunto(s)
ADN/química , ADN/ultraestructura , Nanopartículas del Metal/química , Nanopartículas del Metal/ultraestructura , Excipientes/química , Luz , Ensayo de Materiales , Dispersión de RadiaciónRESUMEN
We propose an interface between the spin of a photon and the spin of an electron confined in a quantum dot embedded in a microcavity operating in the weak-coupling regime. This interface, based on spin selective photon reflection from the cavity, can be used to construct a CNOT gate, a multiphoton entangler and a photonic Bell-state analyzer. Finally, we analyze experimental feasibility, concluding that the schemes can be implemented with current technology.