Surface-enhanced Raman scattering (SERS) cytometry.

Significant advances have been made in the preparation and applications of surface-enhanced Raman scattering (SERS)-active materials for biomolecular analysis. Bright signals, photostability, and narrow spectral features of SERS-active materials offer attractive advantages for cytometric analyses. However, SERS cytometry is still in an early stage of development, and advances in both instrumentation and reagents will be necessary to realize its full potential.

Leveraging nanoscale plasmonic modes to achieve reproducible enhancement of light.

The strongly enhanced and localized optical fields that occur within the gaps between metallic nanostructures can be leveraged for a wide range of functionality in nanophotonic and optical metamaterial applications. Here, we introduce a means of precise control over these nanoscale gaps through the application of a molecular spacer layer that is self-assembled onto a gold film, upon which gold nanoparticles (NPs) are deposited electrostatically. Simulations using a three-dimensional finite element model and measurements from single NPs confirm that the gaps formed by this process, between the NP and the gold film, are highly reproducible transducers of surface-enhanced resonant Raman scattering.

Development of small and inexpensive digital data acquisition systems using a microcontroller-based approach.

Fully digital data acquisition systems for use in flow cytometry provide excellent flexibility and precision. Here, we demonstrate the development of a low cost, small, and low power digital flow cytometry data acquisition system using a single microcontroller chip with an integrated analog to digital converter (ADC). Our demonstration system uses a commercially available evaluation board making the system simple to integrate into a flow cytometer.

High throughput single nanoparticle spectroscopy.

Progress in the development and application of nanoengineered systems is limited by the availability of quantitative measurement techniques. For the engineering of nanoparticle (NP)-based systems, single NP characterization is essential, but existing methods are slow and low throughput. We demonstrate a flow spectroscopy technique capable of analyzing hundreds of nanoparticles per second and use this technique for the high throughput analysis of nanoparticle surface-enhanced resonant Raman scattering (SERRS) tags.

Reconfigurable core-satellite nanoassemblies as molecularly-driven plasmonic switches.

Molecular control of plasmon coupling is investigated in sub-100 nm assemblies composed of 13 nm gold "satellite" particles tethered by reconfigurable DNA nanostructures to a 50 nm gold "core" particle. Reconfiguration of the DNA nanostructures from a compact to an extended state results in blue shifting of the assembly plasmon resonance, indicating reduced interparticle coupling and lengthening of the core-satellite tether. Scattering spectra of the core-satellite assemblies before and after reconfiguration are compared with spectra calculated using a structural model that incorporates the core/satellite ratio determined by TEM imaging and estimates of tether length based upon prior measurements of interparticle separation in DNA linked nanoparticle networks.