Kathryn J. Vannoy

Stochastic nanoelectrochemistry can be employed to track the enzymatic reactions occurring in single attoliter aqueous nanodroplets, probed one nanodroplet at a time. When a nanodroplet irreversibly adsorbs onto an ultramicroelectrode surface, the enzymatic reaction can be traced due to the electrochemical regeneration of the enzyme cofactor. The enzymatic reaction rate has been shown to increase up to 100× for nanodroplets under 1 μm in radius.  

 Multiphase environments are ubiquitous in nature and provide a means for driving specific reactions. Water droplets adsorbed on an electrode immersed in an immiscible liquid phase create a functional three-phase junction (water|oil|electrode). Control over the multiphase geometry can offer control over local reactivity at three-phase boundaries. 

Cocaine is an organic salt that is readily water soluble as a cation and almost insoluble in the deprotonated neutral form. By driving water reduction (consuming protons/producing hydroxide) at an electrode surface we can electroprecipitate cocaine base. The precipitate on the electrode surface can then be electrochemically oxidized by a voltammetric sweep through sufficiently positive potentials. This patented method provides a highly selective technique for cocaine identification in the presence of adulterants without the need to bring any chemicals to the scene!