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Published on: May 9, 2014
Adsorption behavior of plasmid DNA on binary self-assembled monolayers modified gold substrates
Wei-Lun Kao1, Hsun-Yun Chang, Guo-Ji Yen
1Department of Materials Science and Engineering, National Taiwan University, Taipei 106, Taiwan.
Journal of Colloid and Interface Science
|July 6, 2012
Summary
Gold surfaces modified with self-assembled monolayers (SAMs) show tunable potentials affecting plasmid DNA adsorption. Adsorption generally decreases with higher pH and lower amine groups, but electrostatic models alone are insufficient, indicating other interactions are involved.
Area of Science:
- Biomaterials Science
- Surface Chemistry
- Nanotechnology
Background:
- Gold's inertness and tailorable surface properties via self-assembled monolayers (SAMs) are crucial for biocompatibility.
- Binary SAMs with amine and carboxylic acid groups create gold surfaces with tunable isoelectric points (IEPs).
- Understanding surface potential effects on interfacial interactions is key for biomolecule adsorption studies.
Purpose of the Study:
- To investigate how varying surface potentials influence plasmid DNA adsorption onto gold surfaces.
- To determine the role of electrostatic interactions and other forces in DNA-surface binding.
Main Methods:
- Utilized quartz crystal microbalance with dissipation (QCM-D) monitoring.
- Modified gold electrodes with binary SAMs of amine and carboxylic acid functional groups.
- Studied plasmid DNA adsorption in buffered saline solutions across a range of pH values.
Main Results:
- Plasmid DNA adsorption is primarily electrostatic, decreasing with higher pH and reduced surface amine density.
- Stronger electrostatic attraction on amine-rich surfaces led to denser films with slightly decreased apparent thickness.
- Negative surfaces adsorbed negative DNA under certain conditions, suggesting limitations of purely electrostatic models.
Conclusions:
- Surface potential significantly impacts plasmid DNA adsorption on SAM-modified gold.
- Electrostatic interactions are dominant but do not fully explain adsorption behavior.
- Induced dipole (Debye) interactions are necessary to consider for a complete understanding of DNA adsorption.
