A- to B-form transition in DNA between gold surfaces

Area of Science:

• Biophysics
• Materials Science
• Computational Chemistry

Background:

• DNA-templated nanoparticle assembly is crucial for creating superlattice crystals.
• Understanding DNA conformation under these conditions is key to controlling crystal formation.
• Previous assumptions favored A-form DNA due to length matching X-ray data.

Purpose of the Study:

• To characterize the DNA conformation in DNA-linked gold nanoparticle superlattices using molecular dynamics simulations.
• To investigate the structural transformations of DNA strands connecting gold surfaces.
• To determine the role of DNA conformation in the formation of nanoparticle superlattices.

Main Methods:

• Molecular dynamics simulations of DNA-linked gold nanoparticles.
• Modeling DNA bridging two gold surfaces with specific salt and separation conditions.
• Monitoring DNA structure over 40 ns and analyzing coordinate distributions.

Main Results:

• All double-stranded DNA (ds-DNA) transformed from A-form to B-form DNA during simulations.
• Single-stranded DNA (ss-DNA) linkers adsorbed onto the gold surfaces.
• ds-DNA strands exhibited significant bending (approximately 143°) at the gold surface junctions to accommodate B-DNA conformation.

Conclusions:

• The observed short DNA length in nanoparticle superlattices is not due to A-DNA presence.
• DNA conformation dynamically changes from A- to B-form, driven by interactions with gold surfaces.
• This conformational flexibility and surface adsorption are critical factors in DNA-mediated gold nanoparticle assembly.