Visible and near infrared absorption and fluorescence studies of the adsorption and coverage of doxorubicin on single-walled carbon nanotubes

Single-walled carbon nanotubes have been identified as promising materials for drug delivery due to their large specific surface area, their ability to pass through the cell membrane without damaging it and their physicochemical properties, allowing their surface to be easily functionalised. Additionally, their optical properties permit investigation in biological media in the near infrared (the “biological window”). In this paper, adsorption of doxorubicin on single-walled carbon nanotubes dispersed with carboxymethylcellulose salt is monitored by absorption and fluorescence spectroscopy in the visible and near infrared. We confirm that Raman-fluorescence coupled spectroscopy in the near infrared is a useful tool for probing the adsorption of drugs on single-walled carbon nanotubes in a sub-monolayer regime. By combining spectroscopic studies of doxorubicin in the visible range, we propose a protocol for quantifying the amount of adsorbed drug over a broad range of concentrations.