Electrophoretic properties of DNA-modified colloidal gold nanoparticles

Area of Science:

• Nanotechnology
• Biotechnology
• Materials Science

Background:

• Oligonucleotide-modified gold nanoparticles are crucial for DNA biosensors and nanoparticle assembly.
• Understanding how DNA modification affects nanoparticle size is essential for optimizing these applications.

Purpose of the Study:

• To investigate the size changes of 13 nm gold colloids after DNA modification.
• To determine the influence of oligonucleotide length, secondary structure, and modification type on particle size.

Main Methods:

• Electrophoresis experiments were conducted on gold nanoparticles modified with single- and double-stranded oligonucleotides.
• Particles were modified using both thiol-specific and non-specific methods.
• The Ogston model was applied to Ferguson plots derived from electrophoresis data.

Main Results:

• DNA modification increased the effective particle size, with the extent depending on oligonucleotide properties and modification strategy.
• Thiol-specifically modified particles exhibited a thicker DNA layer than non-specifically modified particles.
• The observed DNA layer thickness for thiol-specific modification was less than the fully extended oligonucleotide length, indicating strand flexibility.

Conclusions:

• The size increase of gold nanoparticles upon DNA modification is quantifiable and predictable.
• Thiol-specific modification leads to a more extended DNA layer compared to non-specific adsorption.
• Oligonucleotide flexibility plays a role in the conformation of DNA layers on gold nanoparticle surfaces.