The effect of aniline concentration in the ligand exchange reaction with citrate-stabilized gold nanoparticles.

Sodium citrate reduction of hydrogen tetrachloroaurate is one of the most efficient routes in the synthesis of gold nanoparticles (AuNPs). However, a major limitation of this method is that it results only in citrate-stabilized AuNPs, and exchange reactions of the citrate for another stabilizer must be undertaken in cases where other surface functionalities are desired. These exchange reactions can be studied using a variety of techniques.

Investigation of the interactions between alkanethiol self-assembled monolayers and a liquid overlayer using impedance spectroscopy.

We report on changes in the complex impedance response of a quartz crystal microbalance (QCM) that result from the growth of an alkanethiol monolayer on the electrodes of the device. The purpose of this work is to understand the evolution of the interactions between alkanethiol-gold monolayers and a liquid overlayer as a function of time after initial deposition by evaluating the position, shape, and linewidth of the impedance spectra associated with the monolayer formation. We relate the complex impedance response of the QCM to the mass and viscosity of the monolayer through an established equivalent circuit model.

Optical organophosphate/phosphonate sensor based upon gold nanoparticle functionalized quartz.

Organophosphate/phosphonate (OPP) compounds represent a serious concern to public safety as nerve agents and pesticides. This study discusses the design and use of a class-selective optical sensor which may be used as a presumptive test for OPP presence. This sensor is based upon monitoring of the plasmon resonance (PR) of gold nanoparticles (AuNPs) attached to a planar quartz substrate.