The quantitative characterization of surface-bound thiolate ligands on gold nanoparticles (AuNPs) is difficult because current analysis techniques are indirect, require large sample volumes, and/or require complicated data analysis techniques. Ellman's Reagent (DTNB) � a disulfide compound capable of stoichiometric detection of thiol molecules �has been used directly and indirectly to quantify thiolate ligand coverage of aqueous AuNPs but not to particles dissolved in organic solvents. In this work, we demonstrate the successful application of DTNB-based quantification to hexadecane thiol (HDT) dissolved in organic solvents and to surface-bound HDT on AuNPs in toluene. We have detected thiolate concentrations of < 10-5 M from digested AuNP solutions; this value corresponds to a Au to thiolate ratio of ~ 7:1 for AuNP with d ~ 3.5 nm which is in agreement with calculation and literature. Application of this technique to larger particles and particles with mixed surface composition will also be discussed.

Application of Ellman's Reagent for direct measurement of thiolate surface coverage of gold nanoparticles in organic solvents

245th National Meeting (2013)

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