Metal-enhanced fluorescence in the life sciences: here, now and beyond.

We discuss the phenomenon of enhanced fluorescence in the proximity of metal nanostructures addressing the question of how much fluorescence signal can be obtained from fluorophores in such altered environments. We review its applicability for the methodologies used in the life science, such as immunoassays, flow cytometry and bioimaging. Experimental and theoretical scenarios employing various metal nanostructures - such as homogeneous enhancing substrates, fluorescence-enhancing microbeads, and metal core-dielectric shell nanocomposites - are described.

Detection of specific strains of viable bacterial pathogens by using RNA bead assays and flow cytometry with 2100 Bioanalyzer.

Bead assays are an emerging microbial detection technology with the capability for rapid detection of extremely low levels of viable pathogens. Such technologies are of high value in clinical settings and in the food industry. Here, we perform a bead assay for extracted 16S rRNA from Escherichia coli (strain K12) with the flow cytometry readout on a 2100 Bioanalyzer, a highly accurate, small-scale flow cytometer system.

Dense two-dimensional silver single and double nanoparticle arrays with plasmonic response in wide spectral range.

We report the properties of plasmons in dense planar arrays of silver single and double nanostructures with various geometries fabricated by electron beam lithography (EBL) as a function of their size and spacing. We demonstrate a strong plasmon coupling mechanism due to near-field dipolar interactions between adjacent nanostructures, which produces a major red shift of the localized surface plasmon resonance (LSPR) in silver nanoparticles and leads to strong maximum electric field enhancements in a broad spectral range. The extinction spectra and maximum electric field enhancements are theoretically modeled by using the finite element method.

Simple bead assay for detection of live bacteria (Escherichia coli).

Bead assays are an important rapid microbial detection technology suitable for extremely low pathogen levels. We report a bead assay for rRNA extracted from Escherichia coli K12 that does not require amplification steps and has readout on an Agilent 2100 Bioanalyzer flow cytometry system. Our assay was able to detect 125 ng of RNA, which is 16 times less than reported earlier.