Molecular dynamics simulations have been performed to characterize the conformation of DNA that is present when DNA links gold nanoparticles to form nanoparticle superlattice crystals. To model the DNA-linked gold nanoparticles, four strands of DNA are used to connect two gold surfaces, with a small interstrand separation and high added salt to match experiment. A-form DNA was assumed for the initial conformation, as this form of DNA has a length per base-pair that matches lengths that have been inferred from X-ray measurements. The DNA structure was monitored for 40 ns, and the distributions of the slide and zp coordinates were obtained from the simulations. We find that all the double-stranded DNA (ds-DNA) strands transform from A- to B-DNA during the simulations. In addition, single-stranded DNAa (ss-DNAs) that are used to connect the ds-DNA to each surface are found to become adsorbed on the gold surfaces during this process, and the ds-DNAs bend (∼143Â°) at their junctions with the two gold surfaces to accommodate the observed distance between gold surfaces using B-form DNA. We infer from this that the short length of DNA between the gold surfaces is not due to the presence of A-DNA.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films
- Materials Chemistry