This work reports recent advances in Raman imaging of biological samples tagged with a new contrast agent made of dyes encapsulated inside a single-walled carbon nanotube (dyes@SWNT). By capitalizing on the enhanced cross-section in Raman of the dyes@SWNT, we first demonstrate their use as multispectral Raman tags for imaging. Simple chemical modifications to the nanotubes' sidewall using functionalized polyethylene glycol are shown to provide good dispersion in water media and selective attachment to biological materials. Multicolors tagging, bio-labelling, as well as protein assay applications are also demonstrated. This work presents a thorough characterization of these new tags for biological imaging and highlights new demonstrations of their use in two colors multiplexing.
Optical and Raman multiplexed images of Candida albicans (upper left and center, respectively) labelled with two different dyes@SWNT-PEG-NH2 (schematic representation, right), each tag presents a fingerprint band that is specific to the encapsulated dyes (bottom).