Thursday, April 12, 2012
“Engineering Nanoparticle Tags for Multiplexed Cytometry”
John P. Nolan, PhD, Professor — La Jolla Bioengineering Institute, San Diego, CA
Cytometry, the quantitative, multi-parameter, and high-throughput analysis of individual cells, has revolutionized our understanding of cells and cell systems. A distinguishing feature of cytometry is the use of multiple markers or labels to reveal and quantify heterogeneity at the single cell level not possible using bulk measurements of many cells, which provide only population averages and obscures important information.
To extend the multiplexing capability of cytometry, we are developing instruments, software, and reagents that can exploit the phenomenon of Surface Enhanced Raman Scattering (SERS). High speed spectral flow and image cytometers allow complete optical spectra to be obtained from individual cells at high rates, and spectral unmixing software allow these single cell spectra to be rapidly analyzed to reveal molecular and cellular information. Nanoparticle SERS tags, constructed from plasmonically active metal nanoparticles, exhibit a high density of spectral information, allowing the discrimination of multiple tags within a narrow region of spectral space, while offering sensitivity and specificity comparable to fluorescence-labeled probes.
To improve the performance of our SERS tags, we are developing chemistries to control the size and shape of our nanoparticles, allowing us to tune and optimize their optical properties. Single nanoparticle analysis is a key tool in the development of methods to prepare bright and uniform nanoparticle tags, and we are using a combination of electron microscopy and single nanoparticle spectroscopy to guide our protocol development.