Multisegmented Nanowires Research Articles

Multisegment Nanowire Sensors for the Detection of DNA Molecules

We describe a novel application for detecting specific single strand DNA sequences using multisegment nanowires via a straightforward surface functionalization method. Nanowires comprising CdTe-Au-CdTe segments are fabricated using electrochemical deposition, and electrical characterization indicates a p-type behavior for the multisegment nanostructures, in a back-to-back Schottky diode configuration. Such nanostructures modified with thiol-terminated probe DNA fragments could function as high fidelity sensors for biomolecules at very low concentration. The gold segment is utilized for functionalization and binding of single strand DNA (ssDNA) fragments while the CdTe segments at both ends serve to modulate the equilibrium Fermi level of the heterojunction device upon hybridization of the complementary DNA fragments (cDNA) to the ssDNA over the Au segment. Employing such multisegment nanowires could lead to the fabrication more sophisticated and high multispecificity biosensors via selective functionalization of individual segments for biowarfare sensing and medical diagnostics applications.

Surface modified gold nanowires for mammalian cell transfection

Aminothiol modified gold nanowires have been used as vectors for the delivery of plasmidDNA into two different types of mammalian cells: 3T3 and HeLa. It was measured thatpositively charged gold nanowires with a diameter of 200 nm and a length around5 µm were capable of carrying 1 pg of plasmid DNA per nanowire into cells. Compared with othertransfection reagents, the gold nanowires exhibited the highest transfection efficiency whilealmost no cytotoxicity was observed. In addition, it has been shown that individualnanowires can be visualized with sub-micrometer resolution, which may allow the use offunctionalized multi-segment nanowires as local probes for the investigation of themicroenvironment inside cells.

DNA Assisted Assembly of Multisegmented Nanowires

AbstractThis work demonstrates a highly specific and selective assembly of multisegmented nanowires on prepatterned gold electrodes using DNA hybridization. Multisegmented Au/Pd/Au nanowires were synthesized using template‐directed electrodeposition. Two complementary single‐stranded DNAs modified with thiol tags adsorb on gold electrodes and gold segments of nanowires, and enable the nanowires to assemble across electrodes. The assembled nanowires show ohmic contact with minimum contact resistance. Using these nanowires, the temperature dependent electrical resistance and the sensing performance toward hydrogen were investigated. The temperature coefficient of resistance of nanowires was lower than bulk polycrystalline counterpart, because of higher electron scattering at the surface and grain boundaries of nanowires. The nanowires were sensitive toward hydrogen gas at room temperature with a detection limit of 0.5%.

Orientated Attachment Assisted Self-Assembly of Sb2O3 Nanorods and Nanowires: End-to-End versus Side-by-Side

A facile template-free aqueous solution strategy of oriented attachment assisted self-assembly of Sb2O3 nanorods and nanowires into well-defined complex nanostructures is described in this paper. It is demonstrated that at the temperature of 40 °C, the Sb2O3 nanorods with different lengths (2∼50 μm) and diameters (20∼1000 nm) would axially self-assemble into multisegmented coaxial nanowires by an oriented attachment assisted end-to-end self-assembly process. At the temperature of 80 °C, the Sb2O3 nanowires with diameter of 10∼30 nm would radially self-assemble into nanobelts with hundreds of micrometers in length, typically 400∼1000 nm in width and 20∼60 nm in thickness by an oriented attachment assisted side-by-side self-assembly process. The obtained self-assembled nanostructures were analyzed by a series of methods such as XRD, SEM, EDX, TEM, SAED, HRTEM, and photoluminescence. The formation mechanism of the obtained nanostructures was discussed. The oriented attachment assisted self-assembly strategy ...

Customized Morphologies of Self-Condensed Multisegment Polymer Nanowires

The direct formation of multisegment nanowires consisting of polymer domains by ion beam irradiation is investigated. Cross-linking reactions in the ion tracks result in localized gelation, giving isolated nanowires on substrates. It is demonstrated that the morphology of the final nanostructure is customized by appropriate selection of the ion fluence, combination of polymers, and the solvent employed for development. Octopus-like nanostructures consisting of a tangled hydrophilic polymer core and splayed hydrophobic polymer segments are successfully produced as an example of the process. The present technique provides universal feasibility for the formation of nanostructures based on "any" polymer materials in which radiation induces cross-linking reactions.

Electrochemical Template Synthesis of Multisegment Nanowires: Fabrication and Protein Functionalization

Multisegment nanowires represent a unique platform for engineering multifunctional nanoparticles for a wide range of applications. For example, the optical and magnetic properties of nanowires can be tailored by modifying the size, shape, and composition of each segment. Similarly, surface modification can be used to tailor chemical and biological properties. In this article, we report on recent work on electrochemical template synthesis of nanogap electrodes, the fabrication of multisegment nanowires with embedded catalysts, and the selective functionalization of multisegment nanowires with proteins.

Controlled assembly of multi-segment nanowires by histidine-tagged peptides

A facile technique was demonstrated for the controlled assembly and alignment ofmulti-segment nanowires using bioengineered polypeptides. An elastin-like-polypeptide(ELP)-based biopolymer consisting of a hexahistine cluster at each end(His6-ELP-His6) was generated and purified by taking advantage of the reversiblephase transition property of ELP. The affinity between theHis6 domain of biopolymers and the nickel segment of multi-segment nickel/gold/nickelnanowires was exploited for the directed assembly of nanowires onto peptide-functionalizedelectrode surfaces. The presence of the ferromagnetic nickel segments on the nanowiresallowed the control of directionality by an external magnetic field. Using this method, thedirected assembly and positioning of multi-segment nanowires across two microfabricatednickel electrodes in a controlled manner was accomplished with the expected ohmiccontact.

Biological application of multi-component nanowires in hybrid devices powered by F1-ATPase motors

In this paper, construction of hybrid device by integrating nanowires with F(1)-ATPase motors is described. The nickel nanowires and multi-segment nanowires, including gold and nickel, were fabricated by electrochemical deposition in nanoporous templates. The nickel nanowires functionalized by biotinylated peptide can be assembled directly onto F(1)-ATPase motors to act as the propellers. If the multi-component nanowires, including gold and nickel, were selectively functionalized by the thiol group modified ssDNA and the synthetic peptide, respectively, the biotinylated F(1)-ATPase motors can be attached to the biotinylated peptide on nickel segment of the nanowires. Then, the multi-component nanowires can also be used as the propellers, and one may observe the rotations of the multi-component nanowires driven by F(1)-ATPase motors. Therefore, introduction of multiple segments along the length of a nanowire can lead to a variety of multiple chemical functionalities, which can be selectively bound to cells and special biomolecules. This method provides an insight for the construction of other hybrid devices with its controlling arrangement of different biomolecule on designed nanometer scale structures.

Multisegmented One‐Dimensional Nanorods Prepared by Hard‐Template Synthetic Methods

In the science and engineering communities, the nanoscience revolution is intensifying. As many types of nanomaterials are becoming more reliably synthesized, they are being used for novel applications in all branches of nanoscience and nanotechnology. Since it is sometimes desirable for single nanomaterials to perform multiple functions simultaneously, multicomponent nanomaterials, such as core-shell, alloyed, and striped nanoparticles, are being more extensively researched. Nanoscientists hope to design multicomponent nanostructures and exploit their inherent multiple functionalities for use in many novel applications. This review highlights recent advances in the synthesis of multisegmented one-dimensional nanorods and nanowires with metal, semiconductor, polymer, molecular, and even gapped components. It also discusses the applications of these multicomponent nanomaterials in magnetism, self-assembly, electronics, biology, catalysis, and optics. Particular emphasis is placed on the new materials and devices achievable using these multicomponent, rather than single-component, nanowire structures.

Kinetics of Receptor Directed Assembly of Multisegment Nanowires

We demonstrate the receptor directed end-to-end assembly of multisegment Au/Ni/Au nanowires under agitation in ethanol. The gold end-segments were functionalized with biotin-terminated thiol thereby restricting aggregation to end-to-end attachment via an avidin linkage. On mixing biotin-terminated nanowires with avidin-terminated nanowires, the average chain length is shown to increase linearly with time. The rate constant was independent of the nanowire concentration. Kinetic Monte Carlo simulations were used to model the self-assembly process, and we show that the directed end-to-end assembly of nanowires is similar to the polycondensation of linear polymers.

Directed Assembly of Multisegment Au/Pt/Au Nanowires

We demonstrate directed end-to-end assembly of Au/Pt/Au multisegment nanowires using the biotin/avidin linkage. The formation of a self-assembled monolayer on the central platinum segments is essential to avoid nonspecific binding of the linker group and hence to minimize lateral assembly.

Deposition of AuxAg1 − x / AuyAg1 − y Multilayers and Multisegment Nanowires

multilayers and multisegment nanowires were deposited from a single solution containing and (pH 13). Cyclic voltammograms for deposition from solutions containing and show the characteristic deposition peaks for gold and silver. The composition of the deposited alloys is dependent on the deposition potential (or current) and solution chemistry. Multisegment nanowires were prepared by sequential deposition at and from solutions containing and solution in porous templates. The different segments deposited at and are clearly distinguished by scanning electron microscopy and optical microscopy under blue light illumination. © 2003 The Electrochemical Society. All rights reserved.

Synthesis and Characterization of Nanoporous Gold Nanowires

We report on a two-step process for the fabrication of nanoporous nanowires. The fabrication process involves electrochemical deposition of a single-phase binary alloy into a nanoporous template, followed by subsequent etching of the less noble component. These particles are characterized by diameters of 20 nm or larger, lengths of up to tens of microns, and a porous structure with controlled pore dimensions. In contrast to conventional solid nanoparticles, nonporous nanowires have a high surface area and a well-defined pore morphology. Furthermore, nanoporous segments can be incorporated into multisegment nanorods or nanowires. Here, we demonstrate the fabrication of nanoporous gold (NPG) nanowires and multisegment nanowires incorporating Au/NPG layers and Pt/NPG layers.

Fabrication of nanoporous gold nanowires

We report a method for the fabrication of nanoporous nanowires with high surface area and well-defined pore morphology. The nanoporous nanowires are formed in a two-step process involving electrochemical deposition of a single-phase, two-component AxB1−x alloy into a nanoporous template, and subsequent chemical etching of one component from the alloy after removal from the template. Here, we demonstrate the fabrication of nanoporous gold nanowires and also show that nonporous segments can be incorporated into multisegment nanowires.