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Electron transfer of plurimodified DNA SAMs
Alessandro Rospigliosi1, Rudolf Ehlich, Heinrich Hoerber
1Department of Chemical Engineering, University of Cambridge, Pembroke Street, New Museum Site, Cambridge, United Kingdom. alessandro@rospigliosi.com
Langmuir : the ACS Journal of Surfaces and Colloids
|June 26, 2007
Summary
Phenyl modifications enhance electron transfer through deoxyribonucleic acid (DNA) monolayers on gold surfaces, especially at negative biases. This finding is crucial for developing DNA-based electronic components.
Area of Science:
- Nanotechnology
- Molecular Electronics
- Biophysics
Background:
- Investigating the electronic properties of deoxyribonucleic acid (DNA) is key for molecular electronics.
- Surface modification of DNA can alter its conductivity.
- Scanning tunneling microscopy (STM) is a powerful tool for probing electronic transport at the nanoscale.
Purpose of the Study:
- To investigate the current-voltage (I/V) characteristics of modified deoxyribonucleic acid (DNA) oligonucleotide monolayers on gold.
- To compare the electron transfer efficiency of normal, halogenated, and phenyl-modified DNA.
- To understand the effect of modifications on immobilized versus complementary DNA strands.
Main Methods:
- Fabrication of 18 base pair (bp) DNA oligonucleotide monolayers on template stripped gold (tsg) surfaces.
- Characterization using atomic force microscopy (AFM) and scanning tunneling microscopy (STM).
- Current-voltage (I/V) spectroscopy in tunneling spectroscopy (TS) mode within a +/-250 mV range.
Main Results:
- AFM confirmed the formation of DNA monolayers with expected heights.
- Phenyl-modified DNA monolayers exhibited more efficient electron transfer than normal or halogenated DNA, particularly at negative substrate bias (< -100 mV).
- Unmodified double-stranded (ds) DNA showed slightly better conductivity than modified strands at positive bias, potentially due to increased monolayer order.
Conclusions:
- Phenyl modifications significantly enhance electron transport through DNA monolayers, especially under negative bias.
- Modifications on the surface-bound (thiolated) strand have a greater impact on electron transport than modifications on the complementary strand.
- These findings offer insights into designing DNA-based electronic devices with tunable conductivity.
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