Modulation of direct electron transfer of cytochrome c by use of a molecularly imprinted thin film

Anal Bioanal Chem. 2013 Aug;405(20):6437-44. doi: 10.1007/s00216-013-7009-8. Epub 2013 May 10.

Abstract

We describe the preparation of a molecularly imprinted polymer film (MIP) on top of a self-assembled monolayer (SAM) of mercaptoundecanoic acid (MUA) on gold, where the template cytochrome c (cyt c) participates in direct electron transfer (DET) with the underlying electrode. To enable DET, a non-conductive polymer film is electrodeposited from an aqueous solution of scopoletin and cyt c on to the surface of a gold electrode previously modified with MUA. The electroactive surface concentration of cyt c was 0.5 pmol cm(-2). In the absence of the MUA layer, no cyt c DET was observed and the pseudo-peroxidatic activity of the scopoletin-entrapped protein, assessed via oxidation of Ampliflu red in the presence of hydrogen peroxide, was only 30% of that for the MIP on MUA. This result indicates that electrostatic adsorption of cyt c by the MUA-SAM substantially increases the surface concentration of cyt c during the electrodeposition step, and is a prerequisite for the productive orientation required for DET. After template removal by treatment with sulfuric acid, rebinding of cyt c to the MUA-MIP-modified electrode occurred with an affinity constant of 100,000 mol(-1) L, a value three times higher than that determined by use of fluorescence titration for the interaction between scopoletin and cyt c in solution. The DET of cyt c in the presence of myoglobin, lysozyme, and bovine serum albumin (BSA) reveals that the MIP layer suppresses the effect of competing proteins.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cytochromes c / chemistry*
  • Cytochromes c / metabolism
  • Electrochemical Techniques / instrumentation*
  • Electrochemical Techniques / methods
  • Electrodes
  • Electron Transport / physiology*
  • Fluorescence
  • Membranes, Artificial
  • Molecular Imprinting / methods*
  • Polymers / chemistry
  • Protein Binding
  • Scopoletin / chemistry

Substances

  • Membranes, Artificial
  • Polymers
  • Cytochromes c
  • Scopoletin