(397p) Using Photoluminescence and Proton NMR As Probes to Understand the Interaction of Surfactants and Other Adsorbents With Single Walled Carbon Nanotubes

The ability to understand and control the surface structure of nano materials is a difficult barrier that must be overcome for their practical application in biology and medicine. Single walled carbon nanotubes (SWCNTs) have a large specific surface area and, thus, a high adsorption capacity. The high adsorption capacity can be utilized for practical applications in drug loading but also has important implications on their fate and toxicity as the materials enter natural systems during production and disposal. The changes that occur to the localized region surrounding individual SWCNT can be tracked by photoluminescence (PL), which has been proven to be a quick and reliable probe of SWCNT surfaces. In this approach, the SWCNTs act like a chemical sensor that qualitatively detects the adsorption of molecules around itself, such as drugs, chemicals, or environmental species. While PL provides information about direct contact with the SWCNT, Proton NMR is another probe that we have started to use to track the specific interaction of surfactants with SWCNTs and other molecules adsorbed onto their surface. Changes to the NMR chemical shift of the surfactant molecules provides information about their interaction with either the SWCNTs or other molecules. These changes are shown to correspond to molecular structural changes. By combining PL and Proton NMR analysis, we aim to understand the formation and morphology of both surfactant and solvent structures around SWCNTs. We find characteristic trends in the PL and Proton NMR changes that help elucidate the different interactions occurring between SWCNTs, surfactants, and adsorbents. The ability to understand and control the structure around SWCNTs while interacting with different adsorbents has novel applications in drug delivery and will also improve our understanding of the fate and transport of SWCNTs in natural systems.