Slide-format proteomic biochips based on surface-enhanced nanocluster-resonance

Abstract

The most fundamental properties of metal nanoclusters, namely the high local-field enhancement and nanoscale resonance behavior of the cluster electron plasma when exited by electromagnetic radiation, have been used to set up a variety of sensors transducing biorecognitive interactions into optical signals. This paper focuses on applications of resonant-cluster technology, which enabled us to monitor biorecognitive binding of a variety of proteins on a chip, thus constructing high-throughput interaction-screening devices. Decisive for this type of sensor is the nanometric distance from the local field surrounding a cluster to other parts of the sensor interacting with this field. In particular, the cluster-mirror or cluster-fluorophore distance gives rise to a variety of enhancement phenomena. Depending on the desired application this "resonance"- distance is approximately 5-400 nm. All types of sensor can be set up on photolithographically constructed microchips, but microscopic glass slides can also be employed; this also enables the use of standard devices for dotting and read out. Using slide based chips a standard format of 3,200 microdots (125 microm in diameter) was the basis of either microassays applying direct optical transduction via surfaceenhanced absorption or striking for more sensitivity via surface-enhanced fluorescence.

Optimization of Nanoparticle Size for Plasmonic Enhancement of Fluorescence

“…For this reason, the dyes were not attached directly onto the NP but a silica shell of 5-nm thickness was added. At such distances, the excitation enhancement is still significant and should overcome the negative effect of the quenching, which is much less than at zero distance [1,19,20]. Therefore, the numerically calculated excitation enhancement F a enh is the maximum enhancement of the fluorescence for this system, and, depending on the strength of the quenching, the experimentally measured enhancement will be decreased.…”

Application of Surface Plasmon Resonance Based on a Metal Nanoparticle

“…Wher Pb is the background polarization, and the susceptibility ( P E χ = ) therefore the dielectric function (ɛ) is 14 14…”

“…[12]. They enhanced the sensitivity and response of biosensor based on absorption spectroscopy techniques [13,14]. They shown the resonance angle can be improved by caused by the conformational changes of proteins and enzymes when they bind with analytes of low molecular weights and the response of sensor can be increased by adopting Au nanoshells or nanoclusters.…”

Fluorescence-based assay formats and signal amplification strategies for DNA microarray analysis

“…(Modified from Taton et al, 2000. ) Maximal fluorescence enhancement is observed only from molecules at certain distances from the metal surface, thus the distance must be carefully chosen (Mayer et al, 2001;Liebermann and Knoll, 2000). The enhancement of fluorescence also depends sensitively on the fluorescence quantum yield (QE) of molecules (Weitz et al, 1983).…”