Designable electron transport features in one-dimensional arrays of metallic nanoparticles: Monte Carlo study of the relation between shape and transport

We study the current and shot noise in a linear array of metallic nanoparticles taking explicitly into consideration their discrete electronic spectra. Phonon assisted tunneling and dissipative effects on single nanoparticles are incorporated as well. The capacitance matrix which determines the classical Coulomb interaction within the capacitance model is calculated numerically from a realistic geometry. A Monte Carlo algorithm which self-adapts to the size of the system allows us to simulate the single-electron transport properties within a semiclassical framework. We present several effects that are related to the geometry and the one-electron level spacing like e.g. a negative differential conductance (NDC) effect. Consequently these effects are designable by the choice of the size and arrangement of the nanoparticles.Comment: 13 pages, 12 figure

Preferential adhesion of silver nanoparticles onto crystal faces of α-Cyclodextrin/carboxylic acids inclusion compounds

α-Cyclodextrin (α-CD) inclusion compounds containing the carboxylic acids (octanoic, decanoic, lauric or dodecanoic, myristic or tetradecanoic, palmitic or hexadecanoic and stearic or octadecanoic) as guests were synthesized and applied for preferential adhesion of silver nanoparticles (AgNPs). The binding affinity depends of the chain length of the respective guest and is most efficient for octanoic and decanoic acids. The immobilization of nanoparticles is caused by the spatial replacing of the stabilized shell of the nanoparticles by COOH groups of the guests molecules, located at the entrance of cavity of α-CD, corresponding to the {001} crystal plane. Crystalline coating with nanoparticles provides a means of storing of AgNPs on solids state without aggregation. The stabilization of the particles on the surface is valid for a given length and ordering of the guest in the cavities of the α-CD being the octanoic and decanoic acid the most appropriated. Copyright © 2012 American Sci

Electrically Conducting Nanopatterns Formed by Chemical e-Beam Lithography via Gold Nanoparticle Seeds

We report the formation of thiol nanopatterns on SAM covered silicon wafers by converting sulfonic acid head groups via e-beam lithography. These thiol groups act as binding sites for gold nanoparticles, which can be enhanced to form electrically conducting nanostructures. This approach serves as a proof-of-concept for the combination of top-down and bottom-up processes for the generation of electrical devices on silicon

Multivalency of PEG-thiol ligands affects the stability of NIR-absorbing hollow gold nanospheres and gold nanorods

In this work the effect of multivalency on the stability of NIR-absorbing HAuNSs and AuNRs functionalized by mono-, bi- and tridentate polyethyleneglycol (PEG) thiol ligands is reported. Comparison of commercially-available monodentate and self-synthesized bi- and tridentate methoxy terminated thiol-polyethyleneglycol ligands having molecular weights of around 5000 Da shows the stability increase of HAuNSs and AuNRs for bi- and tridentate ligands, attributed to the multivalency of the ligands. The stability was explored according to three different aspects: (1) stability towards competition reactions with the strong binding ligand dithiothreitol, (2) resistance towards oxidative Au dissolution with potassium cyanide, and (3) colloidal stability, tested by the addition of NaCl. Our PEGylation approach leads to AuNRs where the CTAB concentration is below the detection limit of the performed analytical methods, which is vital for any clinical applications. Furthermore, we found strikingly high biocompatibility after PEGylation for both particle types whereby we observed no significant difference in cytotoxicity comparing the mono-, bi- and tridentate PEGylated species

Gold nanoparticles stabilized with βcyclodextrin-2-amino-4-(4-chlorophenyl)thiazole complex : a novel system for drug transport

While 2-amino-4-(4-chlorophenyl)thiazole (AT) drug and thiazole derivatives have several biological applications, these compounds present some drawbacks, such as low aqueous solubility and instability. A new complex of βCD-AT has been synthesized to increase AT solubility and has been used as a substrate for the deposit of solid-state AuNPs via magnetron sputtering, thus forming the βCD-AT-AuNPs ternary system, which is stable in solution. Complex formation has been confirmed through powder X-ray diffraction and 1D and 2D nuclear magnetic resonance. Importantly, the amine and sulfide groups of AT remained exposed and can interact with the surfaces of the AuNPs. The complex association constant (970 M-1) has been determined using phase solubility analysis. AuNPs formation (32 nm average diameter) has been studied by UV-Visible spectroscopy, transmission/scanning electron microscopy and energy-dispersive X-ray analysis. The in vitro permeability assays show that effective permeability of AT increased using βCD. In contrast, the ternary system did not have the capacity to diffuse through the membrane. Nevertheless, the antibacterial assays have demonstrated that AT is transferred from βCD-AT-AuNPs, being available to exert its antibacterial activity. In conclusion, this novel βCD-AT-AuNPs ternary system is a promising alternative to improve the delivery of AT drugs in therapy

Generation and electrical contacting of gold quantum dots

We report on first tries in generating a system of 20-nm-wide parallel bars as templates for conductive gold wires, decorated with Au-55(PPh3)(12)Cl-6 clusters. The electrical characterization of these quasi one-dimensional arrangements shows pronounced nonlinearity, reflecting charging effects on the small clusters. Furthermore, very first results on the generation of 2.5-nm bars are also reported

Antibacterial activity the βCD-AT-AuNPs, βCD-AT and AT.

<p>Antibacterial activity the βCD-AT-AuNPs, βCD-AT and AT.</p