Welcome to Gaia! :: View User's Journal | Gaia Journals

Figure optionsDownload full-size imageDownload as PowerPoint slide
The nanoparticle-conjugated R406 showed much brighter images (Fig. 2c–f) than the blank and mAb-conjugated cells. Importantly, the emission signals of single mAb–metal complexes could be distinctly isolated over the cellular backgrounds due to enhanced intensities and different lifetimes of the nanoparticle probes. The nanoparticle-conjugated cells also displayed clearly CCR5 expression-dependent images. On the images with low CCR5 expression levels (Fig. 2c–e), the emission signals of mAb–metal complexes could be identified as small and round individual spots, which presumably represented the single receptors or small CCR5 clusters. With increased CCR5 [removed](Fig. 2f–h), the emission signals of mAb–metal complexes appeared as discrete profiles throughout the cell images that may represent large CCR5 clusters.
We also tested the immuno-specificity of the mAb–metal complexes with the CCR5 targets on the cells. For this control experiment, Alexa Fluor 647 goat anti-mouse IgM molecules were covalently bound on the 20 nm silver nanoparticles. These IgG mAb–metal complexes are not expected to bind to the cell surfaces. The IgM–metal complexes were incubated with the highest CCR5 expression HeLa cells. The collected cell images showed on average less than 10 emission spots from the IgM–metal complexes demonstrating the immuno-specificity of CCR5 mAb–Ag complexes with the target CCR5 receptors on the cell surfaces.