Singlet-Oxygen Generation from Individual Semiconducting and Metallic Nanostructures During Near-Infrared Laser Trapping

Bennett E. Smith , Paden B Roder , Jennifer L Hanson , Sandeep Manandhar , Arun Devaraj , Daniel Perea , Woo-Joong Kim , A. L. David Kilcoyne , and Peter J. Pauzauskie

Photodynamic therapy has been used for several decades in the treatment of solid tumors through the optical generation of chemically reactive singlet-oxygen molecules (1O2). Recently, nanoscale metallic and semiconducting materials have been reported to act as photosensitizing agents with additional diagnostic and therapeutic functionality. To date there have been no reports of observing the generation of singlet-oxygen at the level of single nanostructures, particularly at near-infrared (NIR) wavelengths. Here we demonstrate that NIR laser-tweezers can be used to observe the formation of singlet-oxygen produced from individual silicon and gold nanowires via use of a commercially available reporting dye. The laser trap also induces 2-photon photoexcitation of the dye following a chemical reaction with singlet oxygen. Corresponding 2-photon emission spectra confirms the generation of singlet oxygen from individual silicon nanowires at room temperature (30°C), suggesting a range of applications for investigating semiconducting and metallic nanoscale materials for solid tumor photoablation.

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