Enzyme-catalyzed bio-pumping of electrons into Au-nanoparticles: A surface plasmon resonance and electrochemical study

Oleg Lioubashevski, Vladimir I. Chegel, Fernando Patolsky, Eugenii Katz, Itamar Willner*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The enzyme glucose oxidase (GOx) is reconstituted on a flavin adenin dinucleotide (FAD, 1) cofactor-functionalized Au-nanoparticle (Au-NP), 1.4 nm, and the GOx/Au-NP hybrid is linked to a bulk Au-electrode by a short dithiol, 1,4-benzenedithiol (2), or a long dithiol, 1,9-nonanedithiol (3), monolayer. The reconstituted GOx/Au-NP hybrid system exhibits electrical communication between the enzyme redox cofactor and the Au-NP core. Because the thiol monolayers provide a barrier for electron tunneling, the electron transfer occurring upon the biocatalytic oxidation of glucose results in the Au-NPs charging. The charging of the Au-NPs alters the plasma frequency and the dielectric constant of the Au-NPs, thus leading to the changes of the dielectric constant of the interface. These are reflected in pronounced shifts of the plasmon angle, ηp, in the surface plasmon resonance (SPR) spectra. As the biocatalytic charging phenomenon is controlled by the concentration of glucose, the changes in the ηp values correlate with the concentration of glucose. The biocatalytic charging process is characterized by following the differential capacitance of the GOx/Au-NP interface and by monitoring the potential generated on the bulk Au-electrode. The charging of the GOx/Au-NPs is also accomplished in the absence of glucose by the application of an external potential on the electrode, that resulted in similar plasmon angle shifts. The results allowed us to estimate the number of electrons stored per Au-NP at variable concentrations of glucose in the presence of the two different thiol linkers.

Original languageEnglish
Pages (from-to)7133-7143
Number of pages11
JournalJournal of the American Chemical Society
Issue number22
StatePublished - 9 Jun 2004
Externally publishedYes


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