Controlling the lattice parameters of gold nanoparticle FCC crystals with duplex DNA linkers

Abstract

DNA-functionalized gold nanoparticles can be used to induce the formation and control the unit cell parameters of highly ordered face-centered cubic crystal lattices. Nanoparticle spacing increases linearly with longer DNA interconnect length, yielding maximum unit cell parameters of 77 nm and 0.52% inorganic-filled space for the DNA constructs studied. In general, we show that longer DNA connections result in a decrease in the overall crystallinity and order of the lattice due to greater conformational flexibility.

Figure 1.

2-Dimensional and 1-Dimensional SAXS data. (A) 2-D data collected for the N = 39 linker system displayed in false colors. (B) 1-D line profiles of the 2-D data taken for the X-linker, N = 26, 39, and 52 systems demonstrating that the q* peak shifts to smaller values of q with increasing linker length. The 1-Dimensional data for the N = 13 bp linker was not included in part B, as this structure could not be annealed at 35 °C due to the low melting temperature of the A13/T13 duplex region. When N = 13 aggregates were formed at room temperature and subsequently imaged, they did show an FCC structure, but not of the quality of the structures formed with the other linkers (Figure 2, Supporting Figures 1B and 2B).

Figure 2.

Correlating linker length with crystal quality. The orange trace represents the modeled SAXS scattering for a perfectly ordered FCC crystal. The blue traces are the experimental data for the various length linkers and the values above the arrows are the theoretical q/q* peak locations. The strong correlation between simulated and experimental spectra confirms the presence of highly ordered FCC crystal structures.

Figure 3.

Interparticle spacing as a function of total DNA length. A plot of the gold nearest neighbor distances as a function of the total number of bases used to separate them.

Scheme 1.

Materials Sequence and Design^{a a} (A) Illustration of the three-dimensional arrangement of particles forming a face-centered cubic lattice showing the effect of increasing linker length on lattice parameters, (B) sequences of oligonucleotides used to form the various N = X linkers ranging from 13 duplex spacers up to 52; (C) sequences of oligonucleotides used to form the X-linker system