1. Sadao Takabayashi1, William Klein1, Blake Rapp2, Elias Lindau1, Lejmarc Snowball1, Juan Flores-Estrada, Andres Correa, William B. Knowlton1,2, Bernard Yurke1,2, Jeunghoon Lee3 ,Elton Graugnard1 ,Wan
Kuang2, and William L. Hughes1,*
1Department of Materials Science & Engineering, 2Department of Electrical & Computer Engineering, 3Department of Chemistry & Biochemistry Boise State University, Boise, ID 83725
*EMAIL: WILLHUGHES@BOISESTATE.EDU
Maximizing Nanoparticle Attachment onto DNA Origami Nanotubes
3. METHODS
• M13mp18 and 170 staple strands were utilized to form
the DNA nanotube.
• The DNA mixture was annealed at 90˚C for 15min then
cooled to room temperature at the rate of 0.6˚C/min
followed by agarose gel filttraion.
• Nanotubes and AuNPs were combined in a ratio of 5
AuNPs per binding site. The mixture was then
annealed at 45°C for 41 min.
• The nanotube/AuNP solution was purified by agarose
gel electrophoresis to remove unbound AuNPs.
• AuNP arrays were imaged using a Digital Instruments
MultiMode atomic force microscope (AFM).
• The number of attached AuNPs were manually counted
to determine the binding affinity of each design.
1. MOTIVATION
High yield, proximal assembly of metallic nanoparticle arrays is essential
for near-field, diffraction-limited, opto-electronic applications.1 Nanoparticle
arrays, with controlled spacing, have been assembled onto DNA origami
nanostructures.2 Studies of quantum dot attachment using biotin have
shown that using multiple biotin tethers per binding site significantly
increases attachment yield.3 Extending this approach, here we report
multi-tether attachment yields for DNA functionalized gold nanoparticles
(AuNP), as well as AuNP /quantum dot (QD) heterostructures.
2. BINDING STRATEGIES
• One tether per binding site (1x), 2 tethers per binding site (2x), and 4
tethers per binding site (4x) were incorporated into DNA origami.
• The 1x and 2x designs adopted existing origami nanotubes2 while the
4x design required side-by-side dimerization of parallel nanotubes to
create a nano-optical rail (Fig. 1).
• Nanotubes were synthesized with 9 binding sites separated by 43 nm
(Fig. 2).
• The 1x, 2x, and 4x designs contained one of two randomly generated
binding site sequences; sequence α (5’-ACCAGTGCTCCTACG-3’) or
sequence β (5’-TCTCTACCGCCTACG-3’).
• AuNPs (10 nm diameter) were functionalized with 5’ thiolated
oligomers consisting of a 5 thymine spacer and sticky-end
complements (5’-TTTTTcα-3’ or 5’-TTTTTcβ-3’).
Figure 1: Schematics of binding site strategies for attaching DNA conjugated gold
nanoparticles to DNA origami nanotubes. The strategies explore AuNP attachment
yield versus the number of sticky-ends per binding site.
Figure 2: DNA origami schematics with 9 binding sites. The 1x and 2x structures
contained a single nanotube, while the 4x structure contained side-by-side
dimerization of two parallel DNA nanotubes to create a nano-optical rail.
43nm
412nm
1x, 2x
4x
1x Tether 2x Tether 4x Tether
7. SUMMARY
• The 4x binding strategy demonstrated near 100% AuNP attachment onto DNA origami
nanotubes with a 45nm binding site periodicity.
• The αβ structure showed successful attachment of AuNPs onto DNA origami nanotubes
without site bridging, as well as minimizing site periodicity to 14nm.
• The AuNP / QD heterogeneous structure showed successful AuNP and QD attachment
on the origami nanotube with 14nm binding site periodicity utilizing TEM and EDS for
particle analysis.
This project was supported in part by the: (1) NSF Grant No. CCF 0855212, (2) NSF IDR No. 1014922, (3) NIH Grant No. P20 RR016454 from the INBRE Program of the National Center for Research Resources, (4) NIH
Grant No. K25GM093233 from the National Institute of General Medical Sciences, (5) W.M. Keck Foundation Award, (6) Micron MSE PhD Fellowship, (7) LSAMP Grant No. HRD 0901196. We thank Helen Barnes, Greg
Martinez and Emily Flores; Coordinators of the McNair Scholars Program and LSAMP, respectively. Also we would like to thank the students and staff within the Nanoscale Materials & Device Research Group
(nano.boisestate.edu).
ACKNOWLEDGMENTS:REFERENCES:
[1] K. Kelly et al., J. Phys. Chem. B, 107, 668 (2003)
[2] H. Bui, et al., Nano Lett. 10, 3367 (2010).
[3] S.H. Ko, et al., Adv. Func. Mater. 22, 1015 (2012)
4. BINDING STRATEGY YIELDS
• Attachment yields for the three binding site strategies
are shown in Fig.3. As the number of tethers per
binding site increased the attachment yield increased.
• The 4x α and 4x β structures had the highest probability
of attachment (~1) and the lowest standard deviation.
Figure 3: AuNP attachment yields of various structural designs for
the binding strategies shown in Fig. 1 and implemented on the
nanotube designs in Fig. 2.
5. αβ STRUCTURES
• Periodicity less than 29nm induces site-bridging.
• In order to minimize site bridging α and β binding sites were alternated to create 2x and
4x designs with 18 αβ binding sites separated by 14nm each.
• AFM images show AuNP attachment onto DNA origami nanotubes in high yield (Fig. 4).
2x 18site αβ 4x 18site αβ
Figure 4: AFM images of 2x and 4x 18 binding site AB structures.
6. HETEROGENEOUS STRUCTURES
• AuNP/QD heterogeneous structure were designed and synthesized with four 4x single
stranded DNA binding sites and one 2x biotin binding site with 14 nm periodicity.
• AFM and TEM analysis of the heterogeneous structure are shown in Fig. 5, while high
resolution TEM analysis, including EDS, of the nanoparticles is shown in Fig. 6.
Figure 5: AFM (left) image of the AuNP/QD heterogeneous structure shows successful attachment of
nanoparticles to the origami nanotube. TEM image (right) indicates the formation of heterostructures.
0nm
12nm
Figure 6: TEM analysis of free AuNPs and QDs. Low (a), medium (b), and high (d) resolution TEM
images of of mixture of AuNPs and QDs. EDS spectrum from AuNP (c) and QDs (e), respectively.