Water-stable single-walled carbon nanotubes coated by pyrenyl polyethylene glycol for fluorescence imaging and photothermal therapy

Nanomaterials have recently received significant attention as photothermal agents and fluorescence contrast agents for molecular therapeutics due to their unique optical properties (e. g. light absorption). In particular, single-walled carbon nanotubes (SWNTs) have been recently utilized as photothermal agents (for photothermal therapy) because of the solubility of SWNTs as well as their light absorbing capability at the near-infrared region. In this work, we have developed the SWNT-based photothermal agents using pyrene-based PEGylation of SWNTs. FT-IR and/or H-NMR spectroscopies have validated the PEGylation of SWNTs, and it is shown that water-soluble SWNTs are able to generate heat under near-infrared (NIR) irradiation of 5W/cm². Moreover, it is found that our pyrene-based PEGylated SWNTs exhibit the fluorescence characteristic under the excitation wavelength of 340 nm. Our study sheds light on the pyrenyl PEGylated SWNTs as photothermal agents and/or fluorescence contrast agents for the future applications in molecular therapeutics.