COLL 73 |
| Thirunavukarasu Dhanasekaran, Ke Du, and Subra Muralidharan. Department of Chemistry, Western Michigan University, Kalamazoo, MI 49008 |
| Our research program is focused on the design of nanoparticles with appropriate metal chelating ligands for the sensing of various metal ions and their separations in very small volumes. In this regard gold nanoparticles are attractive due to their absorbance in the visible region of the spectrum (523 nm) and high molar absorptivity (109 M-1cm-1) which provides the tool for sensing any metal ion in the nanomolar range if the surface of the gold nanoparticles are derivatized with a metal ion selective ligand. The technique that is most attractive for the separation and quantitation of metal ions in extremely small volumes using visible detection is capillary electrophoresis including the lab-on-a-chip devices. A characterization of the electrical double layer associated with the derivatized nanoparticles is critical as the changes in their electrophoretic mobilities upon binding metal ions will be dictated by the electrical double layer. Major findings of such studies as a function of ionic strength, pH, and dielectric constant of the medium are: (1) calculation of the zeta potential of the nanoparticles from electrophoretic mobilities must account for relaxation effects proposed by Oshima; (2) such calculations indicate that the zeta potential of the nanoparticles reaches a constant value at very low ionic strengths; and (3) an auxiliary ligand must be present in the electrophoretic buffer in addition to the complexing group on the nanoparticles to prevent aggregation of the nanoparticles and obtain the best detection limits. The significant results of these studies will be presented. |
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Nanoscience and Nanotechnology
2:00 PM-5:15 PM, Sunday, March 28, 2004 Marriott -- Grand Ballroom K, Oral
Division of Colloid and Surface Chemistry |