Bioimaging: nanoparticles versus traditional tags

Monday, October 9, 2017 - 14:45
In a ground-breaking study comparing traditional fluorescent tags to Surface Enhanced Raman Scattering (SERS) nanoparticles, researchers have found significant differences between the two imaging methods.
Maria Navas-Moreno and colleagues at the University of California Davis Centre for Biophotonics used Prior Scientific’s H117 motorized precision stage to compare the characteristics of fluorescent probes with SERS nanoparticles while imaging live and fixed cells.
Interest in using SERS NPs rather than traditional fluorescent tags in biological imaging is growing, due to the nanoparticles’ stability and narrow spectral features.
Results from Navas-Moreno and colleagues indicate that the two methods produced similar results in fixed cells, but dramatically different patterns when used on live cells.
Side by side comparison of SERS and fluorescence images. Top: Fluorescence and Raman images of MDA-MB-231 cells stained with CD44 fluorescence and SERS conjugates, respectively. Bottom: Fluorescence and Raman images of SKBR3 cells stained with HER2 fluorescence and SERS conjugates, respectively. All images are accompanied by brightfield images for reference. Blue indicates nuclei of cells. Scale bars are 8 μm. [Scientific Reports 7, 4471(2017)]
The researchers discovered that unexpected cellular interactions with nanoparticles must be taken into account, before using SERS as an alternative to traditional probes. 
As Nava-Moreno writes in Nature Scientific Reports: "When labeling live cells to monitor surface biomarker expression and dynamics, nanoparticles are rapidly uptaken by the cells and become compartmentalised into different cellular regions."
"This behaviour is in stark contrast to that of [traditional] fluorescent antibody conjugates," she adds. "This study highlights the impact of nanoparticle internalization and trafficking on the ability to use SERS nanoparticle-antibody conjugates to monitor cell dynamics.
Nanoparticle labels are internalised and result in a different distribution than fluorescent counterparts. [Scientific Reports 7, 4471(2017)]
Researchers used a custom-built Raman microscopy system, incorporating an H117 stage; the stage provided a large field of view thanks to its large 114 x 75 mm  travel range.
Research is published in Nature Scientific Reports.
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