Boranephosphonate DNA-Mediated Metallization of Single-Walled Carbon Nanotubes

Article abstract of DOI:10.1021/acs.chemmater.6b05182

Single-walled carbon nanotubes (SWNTs), when dispersed in DMSO with boranephosphonate DNA (bpDNA), were efficiently metalized with silver, gold, and palladium nanoparticles (NPs). This was possible by first adsorbing boranephosphonate DNA onto the surface of SWNTs and then bathing with silver, gold, and palladium metal salts, which form the corresponding nanoparticles by reduction of their respective ions without addition of any external reducing agent. Reduction of a redox dye, 2,6-dichlorophenolindophenol (DCPIP), by Pd nanoparticle conjugates (PdNP/bpDNA/SWNT) disclosed the efficient electron transfer properties of these metallized SWNTs. These PdNP/bpDNA/SWNT conjugates were also successfully used to catalyze Heck and Suzuki coupling reactions. Boranephosphonate DNA-mediated metallization of SWNTs therefore provides a new method for fabricating well-defined SWNT-based nanostructures. This discovery should reveal unexpected applications in various research areas ranging from nanoelectronic devices to nanoscale SWNT supported multimetallic catalysts having different compositions.

Full text of DOI:10.1021/acs.chemmater.6b05182

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Article
Boranephosphonate DNA Mediated Metallization
of Single Walled Carbon Nanotubes
Saheli Ganguly, Sibasish Paul, Omer Yehezkeli, Jennifer Cha, and Marvin H. Caruthers
Chem. Mater., Just Accepted Manuscript • DOI: 10.1021/acs.chemmater.6b05182 • Publication Date (Web): 10 Feb 2017
Downloaded from http://pubs.acs.org on February 12, 2017
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Boranephosphonate DNA Mediated Metallization of Single
Walled Carbon Nanotubes
Saheli Gangulya, Sibasish Paula, Omer Yehezkelib, Jennifer Chab and Marvin H. Caruthers*a
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aDepartment of Chemistry and Biochemistry, bDepartment of Chemical and Biochemical
Engineering, University of Colorado, Boulder, Colorado, 80303, USA
ABSTRACT
Single walled carbon nanotubes (SWNTs), when dispersed in DMSO with boranephosphonate
DNA (bpDNA), were efficiently metalized with silver, gold, and palladium nanoparticles (NPs).
This was possible by first adsorbing boranephosphonate DNA onto the surface of SWNTs and
then bathing with silver, gold, and palladium metal salts which form the corresponding
nanoparticles by reduction of their respective ions without addition of any external reducing
agent.Reduction of a redox dye, 2,6ꢀdichlorophenolindophenol (DCPIP), by Pd nanoparticle
conjugates (PdNP/bpDNA/SWNT) disclosed the efficient electron transfer properties of these
metallized SWNTs. These PdNP/bpDNA/SWNT conjugates were also successfully used to
catalyze Heck and Suzuki coupling reactions. Boranephosphonate DNA mediated metallization
of SWNTs therefore provides a new method for fabricating well defined SWNT based
nanostructures. This discovery should reveal unexpected applications in various research areas
ranging from nanoelectronic devices to nanoscale SWNT supported multimetallic catalysts
having different compositions.
INTRODUCTION
Owing to the unique combination of one dimensional structure and topology, single walled
carbon nanotubes exhibit outstanding structural, mechanical and electronic properties. Since their
discovery two decades ago,1carbon nanotubes (CNTs) have been the focal point for research
directed towards several potential applications such as field effect transistors (FET), electrodes
for lithium ion batteries and scanning probes,2ꢀ4 and biosensors.5 Several investigations have
been conducted on the use of DNA as a fabrication material for designing new SWNT
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applications. This is because single stranded DNA (ssDNA), through πꢀstacking interactions with
the sidewalls of CNTs, offers intriguing possibilities for wrapping SWNTs with DNA. For
example considerable research has been carried out with sequence specific ssDNA in attempts to
disperse, via sonication, SWNTs in aqueous solution.6ꢀ11Attempts have also been made to
metalize DNA by sequence specific scaffolding with reducing agents including
glutaraldehyde.7In other research, Han et al. have reported depositing linear arrays of gold
particles onto SWNTs wrapped with thiolated DNA.12 Keren et al., have used ssDNA to
disperse, assemble and pattern SWNTs for microelectronics.13Molecular dynamic simulations
enabled exploration of the physical properties of these multifunctional nanomaterials.14ꢀ16
Oligonucleotides containing boranephosphonate internucleotide linkages were first synthesized
by the Shaw laboratory.17These compounds contain a borane (BH3) moiety in place of one of the
nonbridging phosphate oxygens (Figure 1). Our group has recently reported a new method for
synthesizing boranephosphonate DNA and has shown that this analog reduces metal ions such as
Au (III), Pt (II) and Ag (I).18,19 This research was further extended by constructing a two
dimensional DNA array that was metalized via incorporation of boranephosphonate
DNA.19These arrays were very fragile and observed to rollꢀup into cylinders that formed both
simple and complex structures. Similar results were reported previously with nonꢀmetalized two
dimensional DNA arrays12,20 as well as with DNA arrays that were metalized by other
procedures.21ꢀ23
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This manuscript reports a strategy for organizing noble metal nanoparticles (Ag, Au, Pd) onto
bpDNA wrapped SWNTs. Transmission Electron Microscopy, Scanning Electron Microscopy,
Energy Dispersive Spectroscopy, and Atomic Force Microscopy were used to characterize the
metal NP/bpDNA/SWNT conjugates. The electrochemical and chemical catalytic properties of
PdNP/bpDNA/SWNTs were studied by reduction of 2,6ꢀdichlorophenolindophenol (DCPIP) and
by catalyzing both Heck and Suzuki reactions.
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Figure 1. Chemical structures of DNA and Boranephosphonate DNA
EXPERIMENTAL SECTION
General. SWNTs (7,6ꢀchirality) with a diameter of 0.7ꢀ1.1 nm were purchased from
SigmaꢀAldrich. Other chemicals and buffers were purchased from SigmaꢀAldrich unless noted.
TEM imaging was carried out using CMꢀ10 and FEI Technaiꢀ12 electron microscopes. CMꢀ10
is a 100 KV TEM equipped with a 1K x 1K GatanBioscanDigital Camera and a traditional film
camera. FEI Technaiꢀ12 is a120 KV TEM equipped with two digital cameras: a wideꢀangle, sideꢀ
mounted 2K x2K AMT Camera and a bottomꢀmounted 4K x4K FEI Eagle Camera. Carbon
coated gold grids (400 mesh, Electron Microscopy Science) were used for imaging. Prior to
being used, these grids were cleaned by a plasma treatment. AFM imaging was performed using
NanosurfEasyscan. SEM imaging with EDS was performed using a JEOL6480LV Microscope.
Samples for SEM imaging were deposited on 4” diameter silicon wafers in a 5x5mm chip (TED
Pella Inc). Cyclic voltametric measurements were performed in a three electrode system
consisting of metal NP/bpDNA/SWNT deposited on a glassy carbon electrode (GCE), a
platinum counter electrode and a Ag/AgCl reference electrode. Data was recorded with an
Autolabpotentiostat interfaced with a computer. All of the electrochemical experiments were
performed at room temperature with pH7 phosphate buffer (0.1M) under an argon atmosphere.
UVꢀVIS measurements were completed using a CARY 100 Bio spectrophotometer. The ICP
measurements were performed by ARL 3410+ inductively coupled optical emission spectrometer
(ICPꢀOES).A blank and three standards were used for calibration. Standards were made by
accurately diluting certified standards.
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Synthesis of Boranephosphonate DNA. Oligodeoxynucleotides (ODNs) containing
boranephosphonate linkages were synthesized as described previously.19 Following synthesis,
each resin linked ODN was treated with disodiumꢀ2ꢀcarbamoylꢀ2ꢀcyanoethyleneꢀ1,1ꢀdithiolate
in N, Nꢀdimethylformamide (1.0 M) for 45 minutes in order to remove the methyl protecting
groups from phosphorous, washed repeatedly with anhydrous DMF and acetonitrile, and dried
under a stream of argon. The resin was next treated overnight with a solution containing 940 µL
DMF, 470 µL Et3N, and 630 µL Et3N.(HF)3 in order to remove the silyl protecting groups from
the 2’ꢀdeoxyribonucleoside bases. The resulting resin was washed repeatedly first with DMF and
then with anhydrous acetonitrile. The bpDNA was hydrolyzed from the resin by treatment with 1
mL of 37% ammonium hydroxide in water for 30 minutes and ammonia removed by evaporation
in a SpeedVac. bpDNA was then dissolved in an appropriate solvent for further use.
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Preparation of bpDNA Wrapped SWNTs. bpDNA was purified using acrylamide gel (20%)
electrophoresis and then used for dispersing SWNTs. SWNTs (0.1 mg) in dimethylsulfoxide
(DMSO) and bpDNA in water were dispersed in a total volume of 500 µL (30 µM bpDNA, 10%
water, 90% DMSO). DNA wrapped SWNTs were then prepared following a published
procedure.11The solution was sonicated at 250 watts for 20 min and subsequently centrifuged at
12,000 g for 10 min. The precipitate containing nondispersed SWNTs was discarded. The
supernatant solution containing dispersed SWNTs and unbound DNA was further centrifuged for
10 min at 12,000 g. The precipitate containing DNA wrapped SWNTs was collected and
suspended in DMSO. This solution was used for metallization.
Metalization of bpDNA/SWNTs. Solutions (10 mM) of AgNO3, HAuCl4 and Na2PdCl4 in
millipore water were prepared. These salt solutions (25 µL each) were added to 75 µL aliquots of
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bpDNA wrapped SWNTs suspended in DMSO and the solution incubated at 50 C overnight
with continuous shaking in a MultiꢀTherm Heat Shaker. The solution was centrifuged at 12,000 g
and the precipitate containing MetalNP/bpDNA/SWNTs was suspended in DMSO for
subsequent characterizations and use in various experiments.
Catalysis Reactions with PdNP/bpDNA/SWNTs.
Heck Coupling. 5ꢀIodoꢀ2’ꢀdeoxyribouridine (0.005 g, 0.014 mmol) and styrene were added to a
solution of the PdNP/bpDNA/SWNTcatalyst (1X10ꢀ9 M solutionof Pd NPs as calculated using an
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inductively coupled plasma (ICP) measurement) and triethylamine (0.003 mL) in 1ꢀmethylꢀ2ꢀ
pyrrolidone (NMP, 1.0 mL). This reaction mixture, under an argon atmosphere, was stirred for 5
o
min at room temperature and then for 3 h at 120 C. At this time, TLC indicated complete
conversion to product (Rf 0.3, 9:1 chloroform:methanol). The reaction mixture was evaporated to
dryness, diluted with dichloromethane (5.0 mL) and washed with brine. The organic layer was
dried over sodium sulphate and analyzed by ESI (mass found for C17H18N2O5H+: 331.1485;
calculated mass: 331.1494). The same protocol was used for the reaction of iodobenzene,
styrene, and the PdNP/bpDNA/SWNT catalyst. The product was analyzed by ESI (mass found
for C14H12: 180.1024; calculated mass: 180.1039).
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Suzuki Coupling. 5ꢀiodoꢀ2’ꢀdeoxyribouridine (0.005 g, 0.0015 mmol), pyreneꢀ1ꢀylboronic acid
(0.007 g, 0.03 mmol) and K2CO3 (0.006 g, 0.044 mmol) were placed in a 5.0 mL vial containing
water (2.0 mL) and acetonitrile (0.5 mL). A solution of the PdNP/bpDNA/SWNT catalyst (1X10ꢀ
9 M) in DMSO was centrifuged, the DMSO removed, and the reaction mixture was added to the
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catalyst. The vial was flushed with argon, closed and heated at 55 C. After 5 h TLC analysis
showed almost complete conversion (~90 %) of starting material to product (Rf 0.56, 1:1
hexane:ethylacetate). This reaction was also monitored using reverse phase HPLC (Buffer A:
triethylammonium bicarbonate, 0.05 M; Buffer B: acetonitrile; 0−100% B in 50 min; 55 °C; 1.5
mL/min flow rate). Aliquots of the reaction mixture (100 uL) at the indicated time intervals were
filtered using 0.2 um centrifugal filters and injected onto the HPLC column. Following this
analysis, after 5 h the reaction mixture was allowed to cool to room temperature and extracted
with dichloromethane (2 X 4.0 mL). The combined organic phases were washed with brine,
dried over Na2SO4, and solvent removed in vacuo. The ESI mass for the product was 430.1438
(calculated mass for C25H22N2O5: 430.1429). Pyreneꢀ1ꢀylboronic acid and iodobenzene were also
condensed using the Suzuki reaction towards complete conversion. ESI mass found for 1ꢀ
phenylpyrene was 278.1214 (calculated mass for C22H14: 278.1196).
RESULTS
Preparation of bpDNA Wrapped SWNTs. Previous research has demonstrated that the
relative binding energies of the DNA bases onto SWNTs follow the hierarchy
G>T>A>C.24Moreover Zheng et al. reported that poly (A) and poly (C) strongly selfꢀstack in
aqueous solutions which leads to a minimum free energy of binding to carbon nanotubes and
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therefore a lower dispersion efficiency.6These observations coupled with other studies that report
wrapping SWNTs with d(GT)n in water using vigorous probe sonication12 led us to prepare
d(TbpT)10 and d(GbpT)10 and to observe their interactions with carbon nanotubes.25Our initial
studies followed the research of others where we attempted to use water or methanol/water
solutions coupled with vigorous pulse probe sonication at 750 watts for one hour in order to
disperse the carbon nanotubes wrapped with these bpDNAs. Generally we observed considerable
aggregation and minimal dispersion (Supporting Information, Figure S1). Because it is known
that boranephosphonate DNA is relatively nonpolar when compared to DNA,17we chose to study
the aggregation of bpDNA wrapped carbon nanotubes using a series of polar organic solvents
having high dielectric constants and solubility for bpDNA. These included dimethylsulfoxide,
N,Nꢀdimethylformamide, and formamide. With N,Nꢀdimethylformamide (Supporting
Information, Figure S2 and S3) and formamide (Supporting Information, Figure S4 and S5), ultra
sonication was not efficient for dispersion of SWNTs in the presence of bpDNA. The SWNTs
remained either aggregated or bundled in these solvents. However SWNTs in the presence of
bpDNA were readily dispersed in DMSO (Supporting Information, Figure S6). Previous
studies26 on SWNT dispersion efficiencies relative to sonication times with (dT)30 having natural
phosphate diester linkages showed that high sonication time increased dispersion efficiency but
reduced the length of SWNTs (90 min probe sonication at 130 watts). However in the present
study, 20 min ultrasonication at 250 watts was found to be sufficient for bpDNA mediated
dispersion of SWNTs in DMSO. When measured on a TEM grid, the length and thickness of
these bpDNA dispersed SWNTs from DMSO varied between 0.5ꢀ1.5 µm and 6ꢀ12 nm
respectively. Because the SWNT thickness as specified by the manufacturer was ~1 nm, these
results suggest that the bpDNA wrapped nanotubes were present as thin bundles in DMSO
although we occasionally isolated SWNTs with thickness < 1nm. Closer inspection of these
TEM images (Supporting Information, Figure S6b and c) showed that SWNTs were decorated
throughout their length by localized textures at selected regions of the nanotube sidewalls. These
observations suggest that bpDNA wraps were visualized as nodules on the sidewalls of SWNTs.
The average distance between two consecutive nodules was found to be 50ꢀ60 nm. In order to
authenticate the proposed bpDNA wrapping of SWNTs, control experiments without bpDNA
were performed in DMSO. TEM characterization showed that these SWNTs in the absence of
bpDNA existed in large aggregates (Supporting Information, Figure S7). In a second experiment,
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SWNTs were incubated with DMSO and d(GT)10 (no boranephosphonate linkages on the DNA).
TEM images disclosed that these SWNTs were mostly dispersed in DMSO with some local
aggregated structures (Supporting Information, Figure S8). These observations validate that
bpDNA wrapping helps to disperse SWNTs in DMSO.
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Formation of Metal Nanoparticles (NP) with bpDNA Wrapped SWNTs. Previous research
from this laboratory prompted us to examine whether bpDNA wrapped SWNTs could also
reduce metal salts.18After incubation with AgNO3 and examination by TEM, numerous, discrete
structures of silver nanoparticles (AgNP) were found to be deposited on essentially all SWNTs
(Figure 2a and 2b). The lengths of the individual SWNT conjugates (0.5 µmꢀ1.5 µm) were the
same as found during dispersion of SWNTs and bpDNA in DMSO. The measured height of the
attached nodules was 5ꢀ10 nm although there were a few larger aggregated particles or
nanoclusters (15ꢀ20 nm). As boranephosphonate is a 3eꢀ reduction system, a 20 mer provides 19
sites for reducing Ag+ and in each site 3 Ag+ would be reduced. This leads to a high local
concentration of silver as well as the possibility for stabilization and growth of the nanoparticles.
In order to confirm that these results were dependent on the bpDNA wrapped SWNTs, two
control experiments were conducted. In one experiment, a AgNO3 solution was incubated with
SWNTs in DMSO (no bpDNA). The concentrations of metal and SWNTs were maintained the
same as with the bpDNA wrapped nanotubes. Large black aggregated SWNTs without reduced
silver were found (Supporting Information, Figure S9). In a second experiment, SWNTs were
incubated with DMSO and d(GT)10 (no boranephosphonate). When the silver salt was added and
the resulting mixture studied by TEM (Supporting Information, Figure S10), crosslinking of
SWNTs developed but there were no AgNPs associated with the nanotubes.
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Figure 2. (a), (b) High magnification TEM images of AgNP/bpDNA/SWNT conjugates. (c) EDS analysis of
AgNP/bpDNA/SWNT conjugates. (d) AFM height and amplitude images of a AgNP/bpDNA/SWNT conjugate.
The successful formation of AgNP/bpDNA/SWNTs was also studied using SEM combined
with EDS. SEM images, when compared to TEM, reveal different structures relative to length
and thickness. Thus through SEM imaging of AgNP/bpDNA/SWNTs, certain discrete conjugates
with higher length and thickness than observed by TEM were found (Supporting Information,
Figure S11). During sample preparation, these solutions were applied to silicon wafers, solvent
was removed by air drying, and the preparation was examined by SEM imaging. This procedure
could have caused the interlinking growth of conjugates and extended networks of rope like
structures as can be seen in Figure S11 because it is known that longer incubation times induce
aggregation.27Additionally previous observations have reported that carbon nanotubes have a
strong tendency to cling to each other and form ropes.6EDS experiments on selected nodules
(Figure 2c) indicated the coexistence of C (0.3 keV), Ag (3.0 keV), S (2.3 keV), O (0.5 keV),
and P (2.0 keV). Peaks of S and O are from the DMSO solvent. Of major interest are the peaks
for P and Ag. These peaks indicated the presence of DNA (phosphorus) and that Ag+ had been
reduced by boranephosphonate DNA to silver nanoparticles. In the absence of Ag+, the EDS
spectra of SWNT/bpDNA in DMSO showed peaks for S, O and P at 2.3 keV, 0.5 keV, and 2.0
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keV respectively (Supporting Information, Figure S12). Silicon wafers were used for SEM
samples and this accounts for the peak of Si at 1.7 keV in Figure S12. However this peak was
absent in the EDS spectra of AgNP/bpDNA/SWNTs shown in Figure 2c. This was because the
metal peak was prominent at lower full scale intensity (270 cts) whereas the Si peak was found
only at a higher range. The peak for Na in all EDS plots was from DNA as it was present in the
LCMS of d(GbpT)10 (Supporting Information, Figure S13). AFM imaging of
AgNP/bpDNA/SWNT conjugates depicted the metal decorated features in height and amplitude
(Figure 2d). The size of these metal nodules was found to be ~0.33 µm and the thickness of
individual AgNP/bpDNA/SWNT conjugates varied within 0.33ꢀ2.48 µm.
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Gold deposited SWNT conjugates were also formed when the bpDNA wrapped SWNTs in
.
DMSO were incubated with HAuCl4 3H2O (Figure 3a). These AuNP/bpDNA/SWNTs were
extensively crosslinked and aggregated, when compared to AgNP/bpDNA/SWNT conjugates,
and also displayed gold nanoparticles on the nanotubes. In these images, the size range of
individual AuNPs was about 10 nm (Figure 3a). Because one boranephosphonate linkage (a 3
electron reduction system) reduces one Au3+, the local concentration of gold on SWNTs should
.
be lower when compared to silver. However multivalent Au3+ in acidic solutions (HAuCl4 3H2O)
selfꢀaggregates rather than disperses on SWNTs.28Because bpDNA undergoes solvolysis in the
presence of acid,29 this protic environment encourages aggregation of gold nanoparticles. As
revealed by the TEM images of AuNP/bpDNA/SWNTs and AgNP/bpDNA/SWNTs, AgNPs are
much more precisely deposited onto SWNTs whereas AuNPs are clustered. The EDS spectra of
AuNP/bpDNA/SWNTs from SEM images showed a precise signal for Au (2.3 keV) as well as
the expected peaks for DMSO and DNA (Figure 3b). SEM images also revealed well defined
hexagonal AuNPs deposited on bundled SWNTs (Supporting Information, Figure S14).
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Figure 3. (a) High magnification TEM image of AuNP/bpDNA/SWNT conjugates, (b) EDS analysis of
AuNP/bpDNA/SWNT conjugates.
Treatment of bpDNA and SWNTs in DMSO with Na2PdCl4 generated assemblies of
palladium nanoparticles (Figure 4a). In TEM studies, these PdNP/bpDNA/SWNT conjugates
displayed as small nodules (15ꢀ25 nm) predominantly located in a sequential manner on the
sidewalls of SWNT bundles (0.5 to 1.5 µm in length) and the distance between two consecutive
nanoparticles was 50ꢀ60nm.This value coincides with our previously found bpDNA wrapping
distance for SWNTs after solubilization in DMSO (Supporting Information, Figure S6b and c).
These observations led to a conjecture that bpDNA wraps the SWNTs in a helical fashion
(Figure 4a) with each nodule representing a bpDNA/SWNTconjugate.The EDS spectra showed
the elemental presence of Pd as well as peaks characterized previously (Figure 4b).
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Figure 4. (a) High magnification TEM image of PdNP/bpDNA/SWNT conjugates. (b) EDS analysis of
PdNP/bpDNA/SWNT conjugates.
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Electrocatalytic Activity of PdNP/bpDNA/SWNTs. When metal NP/bpDNA/SWNTs
were placed in buffer solution, they adhered firmly onto a glassy carbon electrode (GCE). This
observation enabled us to use cyclic voltammetry (CV) to study the electrochemical properties of
these conjugates as an immobilized glassy carbon working electrode.30Using CV, the silver, gold,
and palladium bpDNA/SWNT conjugates were tested and the expected electrocatalytic
"fingertips" of the metals were observed, (Supporting Information, Figure S15). By applying
positive potential above 0.8V vs Ag/AgCl, an increase in current was observed, attributed to the
formation of an oxide layer over the gold. As expected, by sweeping the voltage back we could
identify the reduction process which stripped the oxide layer and formedAuo.31Significantly
higher currents were observed in the CV profile of PdNPs. This observation means that a
PdNP/bpDNA/SWNT modified electrode possesses higher electrocatalytic activity which we can
attribute to water oxidation32(Supporting Information, Figure S15). Testing with
AgNP/bpDNA/SWNT we observed a redox couple of Ag+/Ago.33Neither bpDNA nor
SWNT/d(GT)20 yielded this type of conductivity or any redox activity (Supporting Information,
Figure S16).
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As PdNP/bpDNA/SWNT possesses higher electrocatalytic activity than either silver or
gold NP/bpDNA/SWNTs, the ability of the palladium SWNTs to catalyze reduction of DCPIP
was studied.When1ꢀ4 µL of the PdNP/bpDNA/SWNT solution (the 100 µL DMSO solution as
described in the experimental section) was added to an aqueous solution of DCPIP 1.0 mL (3.73
pM), significant absorbance loss of DCPIP was observed at ~600 nm (Figure 5a). A replot of this
data (Figure 5b) shows a steady decrease of absorbance at 600 nm with each additional 1µL of
the PdNP/bpDNA/SWNT solution. Addition of 50 µL of this DMSO PdNP/bpDNA/SWNT
solution to aqueous DCPIP (1.0 mL at 3.73 pM) turned the blue solution pink instantaneously
with a blue shift from 600 nm to 524 nm (Supporting Information, Figure S17). Further addition
of this conjugate (50µL) generated a colorless solution. These color changes were due to partial
(DCPIPH) and complete (DCPIPH2) reduction of DCPIP. This loss of DCPIP absorbance was
also dependent upon temperature. Using the same reaction conditions (10µL of
PdNP/bpDNA/SWNTs, 1.0 mL of the aqueous DCPIP solution at 3.73 pM, 1min), absorbance
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values were found to be ~22% lower at 50 C and 80 oC when compared to 5 oC and 25 oC. The
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DCPIP reduction kinetics was studied by measuring absorbance at 600nm over time (s) after
addition of PdNP/bpDNA/SWNTs. As can be seen from Figure S18a & b (Supporting
Information), a steady decrease in absorbance was observed with time. Two different slopes of a
linear fit of the logarithm plot against time (s) generated two reaction rates of 2.042x10ꢀ4 and
5.0259x10ꢀ5 sꢀ1 (Supporting Information, S18a). The result suggests that more than one
mechanism contributed to the reduction process of the DCPIP, which holds different reaction
rates. Furthermore, the aromaticity of the DCPIP molecule can allow its absorption over the
SWNTs surface, leading to a nonꢀdiffusional reduction process with higher rate.
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Figure 5. DCPIP reduction with palladium SWNTs. (a) Addition of 0ꢀ4 µL of PdNP/bpDNA/SWNT. (b) A plot
showing the loss of absorbance upon addition of PdNP/bpDNA/SWNT.
Catalytic Activity of SWNT/bpDNA/PdNPs. Carbonꢀcarbon bond formation is an
essential transformation of synthetic organic chemistry as the ability to extend a carbon frame via
a series of CꢀC bond forming reactions is paramount to medicinal chemistry and natural product
synthesis. These observation when combined with the CV data (Supporting Information, Figure
S15) led us to further examine the catalytic properties of PdNP/bpDNA/SWNTs in carbonꢀ
carbon bond forming reactions. ICP analysis of PdNP/bpDNA/SWNT conjugates indicated an
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average value of 1X10ꢀ9 M solution of Pd (Supporting Information; Figure S19) which was
sufficient for measuring the catalytic activity of these nodules using the Heck and Suzuki
coupling reactions (Scheme 1). We chose 5ꢀiodoꢀ2’ꢀdeoxyribouridine (1) and iodobenzene (2) as
the halogen sources with styrene and pyreneꢀ1ꢀylboronic acid as the Heck and Suzuki coupling
counterparts respectively. The pyrene functional moiety was selected as it has been shown to
have several significant applications in biological labeling and molecular sensing due to its
ability to form charge transfer complexes and also because it is known to be useful for
synthesizing many valuable compounds.34The Heck coupling reaction between 5ꢀiodoꢀ2’ꢀ
deoxyribouridine and styrene was complete within 3 h to yield (3) while a similar reaction with
iodobenzene generated (4) and was complete after one hour (1ꢀmethylꢀ2ꢀpyrrolidone as solvent,
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120 C, TLC analyses). Both products were characterized using ESI mass analysis. We next
investigated the palladium catalyzed Suzuki crossꢀcoupling reaction. This reaction was carried
out under aqueous conditions at 55 oC and completed within one hour using iodobenzene to yield
(5), whereas 5 h was required for almost complete conversion of 5ꢀiodoꢀ2’ꢀdeoxyribouridine to
the pyrene derivative (6) (Supporting Information; Figure S20). The same Suzuki reaction to
yield (6) takes 22 h with 79% isolated yield using a commercially available palladium
catalyst.35Both products from the Suzuki coupling reactions were characterized using ESI mass
analysis. Both Heck and Suzuki reactions were replicated more than three times and provided
similar observations to those as described above.
Scheme 1. The Heck and Suzuki reactions catalyzed by PdNP/bpDNA/SWNT. NMP= 1ꢀmethylꢀ2ꢀpyrrolidone
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DISCUSSIONS
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The present study represents a first step towards boranephosphonate DNA mediated
SWNT dispersion, metallization with noble metals, and catalysis using these nanoparticles.
When compared to previous research with natural DNA in aqueous methanol solutions,
solubilization of SWNTs with minimum aggregation was possible because these nanotubes were
incubated with bpDNA in the presence of DMSO followed by sonication. Success can be
attributed to several unique properties of this system. Relative to natural DNA,
boranephosphonate DNA is hydrophobic but retains a negative charge. Therefore bpDNA will
noncovalently interact with carbon nanotubes much more efficiently in nonaqueous solvents than
normal DNA. Additionally and owing to its negative charge, the bpDNA/SWNTs will repel one
another and this leads to less aggregation. Another important feature is the use of DMSO as
solvent. It appears to be compatible with both bpDNA and the carbon nanotubesꢀperhaps because
it has a relatively high dielectric constant but retains considerable hydrophobic character.
Additionally DMSO does not solvate anions efficiently which would reduce bpDNA/solvent
interactions and drive the formation of bpDNA/SWNT complexes. Although other even more
hydrophobic DNA analogues exist such as phosphoramidates, phosphotriesters, and alkyl/aryl
phosphonates, we predict that they would not have the same favorable properties. This is because
they lack a negative charge and therefore would not prevent aggregation of nanotubes. Certain
other analogues such as phosphorothioate and phosphorodithioate DNA might be useful as both
are negatively charged and more hydrophobic than natural DNA. However these types of
analogues cannot reduce metals and therefore other applications, such as delivery of therapeutic
oligonucleotides, might benefit from research with these compounds.
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bpDNA/SWNT complexes can be metalized by simple incubation with metal salts. This
is because boranephosphonate DNA has three hydride reducing equivalents at each
internucleotide linkage. To date three metal salts, Ag+, Au+3 and Pd+2, have been shown to
possess a redox potential that allows them to be reduced to metal nanoparticles while bpDNA is
wrapped on SWNTs. TEM imaging has shown that AgNPs have a lower tendency to aggregate
on SWNTs than the corresponding Au or Pd NPs even though there is a higher local silver ion
concentration during reduction. The size of all metal nanoparticles was found to be within the
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range of ~10ꢀ15 nm. Similarly the length of all three metal nanoparticle/SWNT conjugates was
more or less the same. EDS combined with SEM analyses confirmed the elemental presence of
metal NPs and DNA on the SWNTs. As the initial sonication times for dispersing SWNTs was
the same, the length of the conjugates was similar but thickness varied according to the
clustering behavior of the metals onto SWNTs. During SEM studies, interlinking between the
metal SWNT conjugates to form rope like structures was observed. Studies of metal deposition
onto bpDNAs without SWNT backbones showed extensive crosslinked nanostructures with
some large aggregated particles(Supporting Information; Figure S21).18The deposition was not
as sequential or discrete as found when decorated onto bpDNA wrapped SWNTs which
generates a well defined size range. These results suggest that bpDNA mediated metallization of
SWNTs opens up a novel technique to synthesize SWNT supported multimetallic nanoparticles,
which may prove useful in catalytic applications for different chemical syntheses.
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Metal nanostructures exhibit impressive catalytic properties primarily because of novel
physicochemical and electronic properties in conjunction with enhanced surface areas. However,
relative to electrocatalytic performance, there are problems such as being able to disperse metal
nanoparticles uniformly on a CNT surface and to modify electrodes by subsequent
immobilization. In the system described here, excellent adherence property of metal
NP/bpDNA/SWNT conjugates to working electrodes was observed. Presumably this was due to
the unique adsorptive properties of bpDNA to glass electrodes. Utilization of bpDNA in this
context is novel when compared with current electrochemical methods for modifying electrodes
by synthesizing metal nanostructures directly over the bare electrode surface.
DCPIP is a redox dye used for estimating vitamin C concentration and also as a mediator
in sensors for analyzing NADH.When DCPIP accepts electrons, it changes from a blue to a
colorless state (DCPIP(oxidized)+2e→ DCPIP(reduced)). PdNP/bpDNA/SWNT conjugates undergo
reduction at a lower potential as indicated by electrochemical voltammograms (a broad peak at –
0.33 V vs Ag/AgCl) and act as a reducing agent when compared to DCPIP (redox potential 0 V
vs Ag/AgCl reference electrode at pH 7). This well defined potential window in the CV study
and the observed rapid reduction of DCPIP demonstrates that PdNP/bpDNA/SWNTs have
efficient electron transfer properties that validate their usefulness as catalysts. Additionally the
results reported here reveal that metallic palladium nanoparticles, prepared from bpDNA
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wrapped SWNTs, are efficient catalysts for CꢀC bond formation and could prove to be superior
for certain reactions of this type. For example PdNP/bpDNA/SWNT could be useful where
modifications using regular catalysts are difficult such as with long chain linkers. Relative to
DNA modifications, siteꢀselective in corporation of a single modified base is difficult when
canonical base pairs are used. This is because a multiꢀstep procedure is usually required to
synthesize a modified base prior to incorporation into DNA and the modified base must be stable
towards chemical DNA synthesis procedures. Therefore perhaps the use of these
PdNP/bpDNA/SWNTs as mild catalysts to yield complete conversion to a modification at a
specific site within DNA will also prove useful. For example, because iodinated bases such as 5ꢀ
iodoꢀ2’ꢀdeoxyribouridine are stable to DNA synthesis conditions, they can be incorporated at
specific sites within DNA. Post synthesis using either Heck or Suzuki reactions with the very
efficient PdNP/bpDNA/SWNT catalysts, lateꢀstage diversification using CꢀC bond forming
reactions can be used to incorporate a large variety of complex fluorescent probes or other
functional groups into DNA.
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CONCLUSIONS
The present study outlines an approach focusing bpDNA to metallize SWNTs with silver,
gold, or platinum. The process is quite simple. A well defined potential window and good
conductivity,as observed in the CVprofile of PdNP/bpDNA/SWNT,indicates efficient electron
transfer properties for these conjugates. This was confirmed by the reduction of a redox dye
(DCPIP). Palladium nanoparticles, while anchored onto SWNTs, were also shown to be
effective catalysts in the formation of CꢀC bonds via Heck and Suzuki coupling.
MoreovertheseSWNT supported PdNPs demonstrated improved activity when compared to
conventional PdꢀC catalysts. These results provide a promising method for metallization of
SWNTs and the subsequent application of this process to nanoscale metal catalysis using
different bimetallic or multimetallic compositions.
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ASSOCIATED CONTENT
Supporting Information
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The Supporting Information is available free of charge via the ACS Publications website at
http://pubs.acs.org. Included in this content are additional TEM images, SEM/EDS images and
LCMS profile.
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AUTHOR INFORMATION
Corresponding Author
marvin.caruthers@colorado.edu
ACKNOWLEDGMENTS
S.G. and S.P. are thankful to Dr. Subhadeep Roy for meaningful discussions and Diane Hager for
assistance with artwork. AFM, TEM, and SEM/EDS experiments were carried out at the
University of Colorado Nanomaterials Characterization Facility (NCF). This research was
supported by the University of Colorado.
REFERENCES
(1) Iijima, S. Helical Microtubules of Graphitic Carbon. Nature 1991, 354, 56ꢀ58.
(2) Tans, S. J.; Verschueren, A. R. M.; Dekker, C. Roomꢀtemperature Transistor Based on a
Single Carbon Nanotube. Nature 1998, 393, 49ꢀ52.
(3) Dillon, A. C.; Jones, K. M.; Bekkedahl, T. A.; Kiang, C. H.; Bethune, D. S.; Heben, M. J.
Storage of Hydrogen in Singleꢀwalled Carbon Nanotubes. Nature 1997, 386, 377ꢀ379.
(4) Dai, H.; Hafner, J. H.; Rinzler, A. G.; Colbert, D. T.; Smalley, R. E. Nanotubes as
Nanoprobes in Scanning Probe Microscopy. Nature 1996, 384, 147ꢀ150.
(5) Nguyen, C. V.; Delzeit, L.; Cassell, A. M.; Li, J.; Han, J.; Meyyappan, M. Preparation of
Nucleic Acid Functionalized Carbon Nanotube Arrays. Nano Lett. 2002, 2, 1079ꢀ1081.
17
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Page 18 of 22
1
2
3
4
5
6
7
8
9
(6) Zheng, M.; Jagota, A.; Semke, E. D.; Diner, B. A.; Mclean, R. S.; Lustig, S. R.; Richardson,
R. E.; Tassi, N. G. DNAꢀassisted Dispersion and Separation of Carbon Nanotubes. Nat.
Mater. 2003, 2, 338ꢀ342.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
(7) Keren, K.; Berman, R. S.; Braun, E. Patterned DNA Metallization by SequenceꢀSpecific
Localization of a Reducing Agent. Nano Lett. 2004, 4, 323ꢀ326.
(8) Zhao, W.; Gao, Y.; Brook, M. A.; Li, Y. Wrapping Singleꢀwalled Carbon Nanotubes with
Long Singleꢀstranded DNA Molecules Produced by Rolling Circle Amplification. Chem.
Commun. 2006, 34, 3582ꢀ3584.
(9) Liu, Y.; Liang, P.; Zhang, HꢀY; Guo, DꢀS. CationꢀControlled Aqueous Dispersions of
AlginicꢀAcidꢀWrapped MultiꢀWalled Carbon Nanotubes. Small 2006, 2, 874ꢀ878.
(10) Jeynes, J.; Charles, G.; Mendoza, E.; Chow, D. C. S.; Watts, P. C. P.; McFadden, J.; Silva,
S. R. P. Generation of Chemically Unmodified Pure SingleꢀWalled Carbon Nanotubes by
Solubilizing with RNA and Treatment with RibonucleaseꢁA. Adv. Mater. 2006,18, 1598ꢀ1602.
(11) Dukovic, G.; Balaz, M.; Doak,P.; Berova, N. D.; Zheng, M.; Mclean, R. S.; Brus, L. E.
Racemic SingleꢀWalled Carbon Nanotubes Exhibit Circular Dichroism When Wrapped with
DNA. J. Am. Chem. Soc. 2006, 128, 9004ꢀ9005.
(12) Han, X.; Li, Y.; Deng, Z. DNAꢀWrapped Single Walled Carbon Nanotubes as Rigid
Templates for Assembling Linear Gold Nanoparticle Arrays. Adv. Mater. 2007,19, 1518ꢀ
1522.
(13) Keren, K.; Berman, R. S.; Buchstab, E.; Sivan, U.; Braun, E. DNAꢀTemplated Carbon
Nanotube FieldꢀEffect Transistor. Science, 2003, 302,1380ꢀ1382.
18
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1
2
3
4
5
6
7
8
9
(14) Johnson, R. R.; Kohlmeyer, A.; Johnson, A. T. C.; Klein, M. L. Free Energy Landscape of a
DNA−Carbon Nanotube Hybrid Using Replica Exchange Molecular Dynamics. Nano Lett.,
2009, 9, 537ꢀ541.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
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40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
(15) Johnson, R. R.; Johnson, A. T. C.; Klein, M. L. Probing the Structure of DNA−Carbon
Nanotube Hybrids with Molecular Dynamics. Nano Lett., 2008, 8, 69ꢀ75.
(16) Chein, M.W.; Johnson, R. R.; Pillai, S. R.;Singh, S. R.; Johnson, A. T. C. Jr. Mechanics and
Energetics of DNA Hybridization on SingleꢀWalled Carbon Nanotubes Explored Using
Adaptive Biasing Force Calculations. J.Phys.Chem.C. 2014, 118, 2209ꢀ2214.
(17) Sood, A.; Shaw, B. R.; Spielvogel, B. F. Boronꢀcontaining Nucleic Acids. 2. Synthesis of
Oligodeoxynucleoside Boranophosphates. J. Am. Chem. Soc. 1990, 112, 9000ꢀ9001.
(18) Roy, S.; Olesiak, M.; Pedar, P.; McCuen, H.; Caruthers, M. H. Reduction of Metal Ions by
Boranephosphonate DNA. Org.&Biomol. Chem. 2012, 10, 9130ꢀ9133.
(19) Roy, S.; Olesiak, M.; Shang, S.; Caruthers, M. H. Silver Nanoassemblies Constructed from
Boranephosphonate DNA. J. Am. Chem. Soc. ,2013, 135, 6234ꢀ6241.
(20) Zheng, J.; Constantinou, P. E.; Micheel, C. A.; Alivisatos, A. P.; Kiehl, R. A.; Seeman, N.
C. TwoꢀDimensional Nanoparticle Arrays Show the Organizational Power of Robust DNA
Motifs. Nano Lett. 2006, 6, 1502ꢀ1504.
(21) Seeman, N. C. DNA in a Material World. Nature 2003, 421, 427ꢀ431.
(22) Liu, D.; Wang, M.; Deng, Z.; Walulu, R.; Mao, C. Tensegrity:ꢁ Construction of Rigid DNA
Triangles with Flexible FourꢀArm DNA Junctions. J. Am. Chem. Soc. 2004, 126, 2324ꢀ2325.
(23) Ding, B.; Sha, R.; Seeman,N, C. Pseudohexagonal 2D DNA Crystals from Double
Crossover Cohesion. J. Am. Chem. Soc. 2004, 126, 10230ꢀ10231.
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(24) Das, A.; Sood, A. K.; Maiti, P. K.; Das, M.; Varadarajan, R.;. Rao, C. N. R. Binding of
nucleobases with singleꢀwalled carbon nanotubes: Theory and experiment. Chem.Phys.Lett.
2008, 453, 266ꢀ273.
10
11
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16
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(25) For this manuscript the completely boronated 20 mer 5’ꢀdeoxyoligonucleotide will be
abbreviated as d(TbpT)10 or d(GbpT)10. Although both d(TbpT)10 and d(GbpT)10 were
successfully employed, the results reported in this manuscript used only d(GbpT)10. Therefore
the term bpDNA when used relative to this work, refers exclusively to d(GbpT)10.
(26) Lahiji, R. R.; Dolash, B. D.; Bergstrom, D. E.; Reifenberger, R. Oligodeoxyribonucleotide
Association with SingleꢀWalled Carbon Nanotubes Studied by SPM. Small 2007, 3, 1912ꢀ
1920.
(27) Zhao, Z.; Liu, Y.; Yan, H. DNA Origami Templated Selfꢀassembly of Discrete Length
Single Wall Carbon Nanotubes. Org. & Biomol. Chem. 2013, 11, 596ꢀ598.
(28) Han, X.; Li, Y.; Wu, S.; Deng, Z. A General Strategy Toward pHꢀControlled Aggregation–
Dispersion of Gold Nanoparticles and SingleꢀWalled Carbon Nanotubes. Small, 2008, 4, 326ꢀ
329.
(29) Xue, C.; Birel, O.; Xue, Y.; Dai, L.; Urbas, A.; Li, Q. pH and Temperature Modulated
Aggregation of Hydrophilic Gold Nanorods with Perylene Dyes and Carbon Nanotubes. J.
Phys. Chem. C. 2013, 117, 6752ꢀ6758.
(30) Hu, C.; Zhang, Y.; Bao, G.; Zhang, Y.; Liu, M.; Wang, Z. L. DNA Functionalized Singleꢀ
Walled Carbon Nanotubes for Electrochemical Detection. J. Phys. Chem. B. 2005, 43,
20072ꢀ20076.
(
31) Holze, R. The Adsorption of Thiophenol on Gold – a Spectroelectrochemical Study. Phys.
Chem. Chem. Phys. 2015, 17 (33), 21364–21372.
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(32) Dokoutchaev, A. G.; Abdelrazzaq, F.; Thompson, M. E.; Willson, J.; Chang, C.; Bocarsly,
A. Multicomponent Electrodes for Water Oxidation:ꢁ From Combinatorial to Individual
Electrode Study. Chem. Mater. 2002, 14 (8), 3343–3348.
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(33) Stuart, E. J. E.; Tschulik, K.; Lowinsohn, D.; Cullen, J. T.; Compton, R. G. Gold Electrodes
from Recordable CDs for the Sensitive, SemiꢀQuantitative Detection of Commercial Silver
Nanoparticles in Seawater Media. Sens. Actuators B Chem. 2014, 195, 223–229.
(34) Miyaura, N.; Suzuki, A. PalladiumꢀCatalyzed CrossꢀCoupling Reactions of Organoboron
Compounds. Chem. Rev. 1995, 95, 2457ꢀ2483.
(35) Amann, N.; Pandurski, E.; Fiebig,T.; Wagenknecht, HꢀA. Electron Injection into DNA:
Synthesis and Spectroscopic Properties of PyrenylꢀModified Oligonucleotides. Chem. Eur. J.
2002, 8, 4877ꢀ4883.
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