Most of AuNP analytical applications take advantage of its unique electromagnetic properties.  The competitive ligand adsorption method (CELA) presented herein is a novel AuNP-based analytical method that takes advantage of the chemical property of AuNP that organothiols compete with each other and self-assemble onto gold surface.  With this method, the analyte and the probe organothiol are mixed simultaneously with AuNP to allow equilibrium adsorption.  The concentration of analyte is deduced from the amount of the probe organothiol replaced by the analyte from the AuNP.   Using mercaptobenzimidazole as the probe organothiol and homocysteine as the model analyte, the detection sensitivity of this CELA method is ~10 mM.   Importantly both the dynamic range and the detection limit of this method can be readily tuned by combining this CELA with the common sample pre-concentration or dilution methods where the probe organothiol is used as the internal reference for determination of the concentration or dilution factors.

Competitive equilibrium ligand adsorption onto gold nanoparticle for organothiol quantification

242nd National Meeting (2011)

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