Multiplexed Multi-Color Raman Imaging of Live Cells with Isotopically Modified Single Walled Carbon Nanotubes

We show that single walled carbon nanotubes with different isotope compositions exhibit distinct Raman Gband peaks and can be used for multiplexed multi-color Raman imaging of biological systems. Cancer cells with specific receptors are selectively labeled with 3 differently colored SWNTs conjugated with various targeting ligands including Herceptin, anti-Her2, Erbitux, anti-Her1, and RGD peptide, allowing for multi-color Raman imaging of cells in a multiplexed manner. SWNT Raman signals are highly robust against photo-bleaching, allowing long term imaging and tracking. With narrow peak features, SWNT Raman signals are easily differentiated from the auto-fluorescence background. The SWNT Raman excitation and scattering photons are in the near-infrared region, which is the most transparent optical window for biological systems in vitro and in vivo. Thus, SWNTs are novel Raman tags promising for multiplexed biological detection and imaging.