7 research outputs found
DNA-Linker-Induced Surface Assembly of Ultra Dense Parallel Single Walled Carbon Nanotube Arrays
Ultrathin film preparations of single-walled carbon nanotube (SWNT) allow economical utilization of nanotube properties in electronics applications. Recent advances have enabled production of micrometer scale SWNT transistors and sensors but scaling these devices down to the nanoscale, and improving the coupling of SWNTs to other nanoscale components, may require techniques that can generate a greater degree of nanoscale geometric order than has thus far been achieved. Here, we introduce linker-induced surface assembly, a new technique that uses small structured DNA linkers to assemble solution dispersed nanotubes into parallel arrays on charged surfaces. Parts of our linkers act as spacers to precisely control the internanotube separation distance down to <3 nm and can serve as scaffolds to position components such as proteins between adjacent parallel nanotubes. The resulting arrays can then be stamped onto other substrates. Our results demonstrate a new paradigm for the self-assembly of anisotropic colloidal nanomaterials into ordered structures and provide a potentially simple, low cost, and scalable route for preparation of exquisitely structured parallel SWNT films with applications in high-performance nanoscale switches, sensors, and meta-materials
Self-assembly of carbon nanotubes into two-dimensional geometries using DNA origami templates
A central challenge in nanotechnology is the parallel fabrication of complex geometries for nanodevices. Here we report a general method for arranging single-walled carbon nanotubes in two dimensions using DNA origami—a technique in which a long single strand of DNA is folded into a predetermined shape. We synthesize rectangular origami templates (~75 nm × 95 nm) that display two lines of single-stranded DNA ‘hooks’ in a cross pattern with ~6 nm resolution. The perpendicular lines of hooks serve as sequence-specific binding sites for two types of nanotubes, each functionalized non-covalently with a distinct DNA linker molecule. The hook-binding domain of each linker is protected to ensure efficient hybridization. When origami templates and DNA-functionalized nanotubes are mixed, strand displacement-mediated deprotection and binding aligns the nanotubes into cross-junctions. Of several cross-junctions synthesized by this method, one demonstrated stable field-effect transistor-like behaviour. In such organizations of electronic components, DNA origami serves as a programmable nanobreadboard; thus, DNA origami may allow the rapid prototyping of complex nanotube-based structures
DNA-Linker-Induced Surface Assembly of Ultra Dense Parallel Single Walled Carbon Nanotube Arrays
DNA-Linker-Induced Surface Assembly of Ultra Dense Parallel Single Walled Carbon Nanotube Arrays
Ultrathin film preparations of single-walled carbon nanotube
(SWNT)
allow economical utilization of nanotube properties in electronics
applications. Recent advances have enabled production of micrometer
scale SWNT transistors and sensors but scaling these devices down
to the nanoscale, and improving the coupling of SWNTs to other nanoscale
components, may require techniques that can generate a greater degree
of nanoscale geometric order than has thus far been achieved. Here,
we introduce linker-induced surface assembly, a new technique that
uses small structured DNA linkers to assemble solution dispersed nanotubes
into parallel arrays on charged surfaces. Parts of our linkers act
as spacers to precisely control the internanotube separation distance
down to <3 nm and can serve as scaffolds to position components
such as proteins between adjacent parallel nanotubes. The resulting
arrays can then be stamped onto other substrates. Our results demonstrate
a new paradigm for the self-assembly of anisotropic colloidal nanomaterials
into ordered structures and provide a potentially simple, low cost,
and scalable route for preparation of exquisitely structured parallel
SWNT films with applications in high-performance nanoscale switches,
sensors, and meta-materials
Formation of Disk- and Stacked-Disk-like Self-Assembled Morphologies from Cholesterol-Functionalized Amphiphilic Polycarbonate Diblock Copolymers
A cholesterol-functionalized aliphatic
cyclic carbonate monomer,
2-(5-methyl-2-oxo-1,3-dioxane-5-carboxyloyloxy)Âethyl carbamate (MTC-Chol),
was synthesized. The organocatalytic ring-opening polymerization of
MTC-Chol was accomplished by using <i>N</i>-(3,5-trifluoromethyl)Âphenyl-<i>N</i>′-cyclohexylthiourea (TU) in combinations with bases
such as 1,8-diazabicyclo[5.4.0]Âundec-7-ene (DBU) and (−)-sparteine,
and kinetics of polymerization was monitored. By using mPEG-OH as
the macroinitiator, well-defined amphiphilic diblock copolymers mPEG<sub>113</sub>-<i>b</i>-PÂ(MTC-Chol)<sub><i>n</i></sub> (<i>n</i> = 4 and 11) were synthesized. Under aqueous
conditions, these block copolymers self-assembled to form unique nanostructures.
Disk-like micelles and stacked-disk morphology were observed for mPEG<sub>113</sub>-<i>b</i>-PÂ(MTC-Chol)<sub>4</sub> and mPEG<sub>113</sub>-<i>b</i>-PÂ(MTC-Chol)<sub>11</sub>, respectively,
by transmission electron microscopy (TEM). Small-angle neutron scattering
supports the disk-like morphology and estimates the block copolymer
micelle aggregation number in the dispersed solution. The hydrophobic
nature of the cholesterol-containing block provides a versatile self-assembly
handle to form complex nanostructures using biodegradable and biocompatible
polymers for applications in drug delivery