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Interfacial electron-shuttling processes across KolliphorEL monolayer grafted electrodes
Khadijeh Nekoueian1,2,3, Christopher E Hotchen1, Mandana Amiri2
1†Department of Chemistry, University of Bath, Bath BA2 7AY, United Kingdom.
ACS Applied Materials & Interfaces
|June 25, 2015
Summary
Grafting KolliphorEL onto electrodes blocks electron transfer, but allows mediated transfer with ferrocene derivatives. This enables amplified electroanalytical signals for specific ferrocene compounds.
Area of Science:
- Electrochemistry
- Materials Science
- Nanotechnology
Background:
- KolliphorEL, a poly(ethylene glycol)-based molecule, is used to transport hydrophobic drugs.
- Surface modification of electrodes can alter electron transfer kinetics.
Purpose of the Study:
- To investigate the effect of covalently grafted KolliphorEL on electron transfer at a glassy-carbon electrode.
- To explore the potential of KolliphorEL-modified electrodes for mediated electron transfer using ferrocene derivatives.
Main Methods:
- Electrochemical anodization to graft KolliphorEL onto glassy-carbon electrodes.
- X-ray Photoelectron Spectroscopy (XPS) to confirm monolayer formation.
- Voltammetry and impedance spectroscopy to study electron transfer kinetics.
- Systematic investigation of five ferrocene derivatives as electron shuttle guests.
Main Results:
- KolliphorEL grafting completely blocked electron transfer for the Fe(CN)6(3-/4-) redox system.
- In the presence of ferrocene derivatives, mediated electron transfer occurred via a shuttle mechanism.
- Amplification of ferrocene electroanalytical signals was observed.
- Electron shuttle efficiency varied among ferrocene derivatives, with (dimethylaminomethyl)ferrocene showing the highest efficiency.
Conclusions:
- Covalently grafted KolliphorEL monolayers can effectively mediate electron transfer.
- This provides a strategy for amplifying electroanalytical signals of specific guest molecules.
- The efficiency of mediation depends on the ferrocene derivative's structure.
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