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Immobilizing DNA on gold via thiol modification for atomic force microscopy imaging in buffer solutions
M Hegner1, P Wagner, G Semenza
1Department of Biochemistry, Swiss Federal Institute of Technology, ETH Zentrum, Zürich.
FEBS Letters
|December 28, 1993
Summary
Thiolated DNA molecules were synthesized and shown to strongly bind to gold surfaces. Atomic force microscopy confirmed their structural integrity in liquid, enabling visualization of DNA on gold. Keywords: thiolated DNA, gold surfaces, atomic force microscopy.
Area of Science:
- Biophysics
- Materials Science
- Nanotechnology
Background:
- Sulfur-containing organic molecules, including thiols, dialkylsulfides, and dialkyldisulfides, exhibit strong chemisorption on gold surfaces.
- Gold surfaces possess unique properties amenable to molecular interactions and imaging.
Purpose of the Study:
- To synthesize DNA molecules functionalized with thiol groups at both ends.
- To investigate the binding affinity and structural integrity of these thiolated DNA molecules on ultraflat gold surfaces.
- To demonstrate the capability of imaging DNA-gold interfaces using Atomic Force Microscopy (AFM) in liquid environments.
Main Methods:
- Polymerase chain reaction (PCR) amplification of plasmid DNA using primers modified with a thiol-terminated alkyl chain (HS-(CH2)6-arm) at the 5'-end.
- Preparation of large, ultraflat gold surfaces.
- Atomic Force Microscopy (AFM) imaging in aqueous solutions and propanol.
Main Results:
- Successful synthesis of DNA with thiol groups at both termini.
- Strong adsorption of thiolated DNA onto the prepared gold surfaces.
- AFM imaging in liquids revealed DNA molecules with lengths consistent with the native B-conformation, indicating structural preservation.
Conclusions:
- Thiolated DNA can be effectively immobilized on gold surfaces with high affinity.
- AFM is a suitable technique for visualizing DNA on gold substrates in liquid media.
- The study confirms the structural integrity of DNA upon immobilization, preserving its native B-conformation.