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The technique for producing quantum-sized zinc oxide (ZnO) particles is much safer than a technique that used hydrogen sulfide gas to produce cadmium sulfide and zinc sulfide nanoparticles. A further advantage of this method is the ability to sample the solution over time and hence determine the growth kinetics.

An experiment is developed for a laboratory course on nanostructures, as part of the undergraduate Bachelor of Science degree in nanotechnology at Flinders University. Designed to demonstrate the relationship between molecular order and the optical dielectric properties of the liquid crystalline state, the experiment is shown to be a useful tool for students studying nanotechnology.

Scanning probe microscopy techniques were used to study immobilized enzyme molecules of glucose oxidase (GOD) on a biosensor surface. The study was carried out in order to optimize atomic force microscopy (AFM) imaging and reveal themolecular resolution of individual GOD molecules. Chemically modified AFM tips and the light tapping mode were found to be the optimal conditions for imaging soft biomolecules such as GOD. The information obtained from the AFM images included spatial distribution and organization of the enzyme molecules on the surface, surface coverage and shape, size and orientation of individual molecules. Two typical shapes of GOD molecules were found, spherical and butterfly, which are in accordance with the shapes obtained from scanning tunnelling microscopy (STM) images. Using a model of the orientation of the GOD molecules on the surface, these shapes are assigned to the enzyme standing and lying on the surface. After AFM tip deconvolution, the size of the spherical shaped GOD molecules was found to be 12 ±2.1 nm in diameter, whereas the butterfly shapes were 16.5 ± 3.3 nm x10.2 ± 2.5 nm. Corresponding STM images showed smaller lateral dimensions of 10 _1nm_ 6 ±1nm and 6.5 ± 1 nm x5 ± 1 nm. The disagreement between these two techniques is attributed to the deformation of the GOD molecules caused by the tapping process.

The difference between solution and surface properties such as pK(sub a) is illustrated enabling students to understand the differences between nanoscale and macroscopic systems. Details regarding the usage of electrochemical instrumentation, such as a potentiostat, and of the technique such as cyclic voltammetry are given.

In this work a simple and up-scalable technique for creating arrays of high purity carbon nanotubes via plasma enhanced chemical vapor deposition is demonstrated. Inductively coupled plasma enhanced chemical vapor deposition was used with methane and argon mixtures to grow arrays in a repeatable and controllable way. Changing the growth conditions such as temperature and growth time led to a transition between single and multi-walled carbon nanotubes and was investigated. This transition from single to multi-walled carbon nanotubes is attributed to a decrease in catalytic activity with time due to amorphous carbon deposition combined with a higher susceptibility of single-walled nanotubes to plasma etching. Patterning of these arrays was achieved by physical masking during the iron catalyst deposition process. The low growth pressure of 100 mTorr and lack of reducing gas such as ammonia or hydrogen or alumina supporting layer further show this to be a simple yet versatile procedure. These arrays were then characterized using scanning electron microscopy, Raman spectroscopy and x-ray photoelectron spectroscopy. It was also observed that at high temperature (550 °C) single-walled nanotube growth was preferential while lower temperatures (450 °C) produced mainly multi-walled arrays. [ABSTRACT FROM AUTHOR]

Ruthenium porphyrin functionalized single-walled carbon nanotube arrays are prepared by using coordination of the axial position of the metal ion onto 4-aminopyridine preassembled single-walled carbon nanotubes directly anchored to a silicon (100) surface (SWCNTs-Si). The results have suggested the ruthenium porphyrin modified electrodes are excellent candidates for molecular memory devices and light harvesting antennae.

A strategy is used to investigate that the electron transfer properties of redox enzymes with microperoxidase (MP) is attached to the end of aligned single walled carbon nanotubes. In studies of the electrochemical properties of biologically relevant molecules such as hydrogen peroxide, NADH, and dopamine, carbon nano-tube-modified electrodes have shown superior performance as compared to other carbon electrodes.

A roll-to-roll compatible, high throughput process is reported for the production of highly conductive, transparent planar electrode comprising an interwoven network of silver nanowires and single walled carbon nanotubes imbedded into poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS). The planar electrode has a sheet resistance of between 4 and 7 Ω□−1 and a transmission of ＞86% between 800 and 400 nm with a figure of merit of between 344 and 400 Ω−1. The nanocomposite electrode is highly flexible and retains a low sheet resistance after bending at a radius of 5 mm for up to 500 times without loss. Organic photovoltaic devices containing the planar nanocomposite electrodes had efficiencies of ∼90% of control devices that used indium tin oxide as the transparent conducting electrode. [ABSTRACT FROM AUTHOR]

The understanding of the electrochemical properties of nanopores is the key factor for better understanding their performance and applications for nanopore-based sensing devices. In this study, the influence of pore dimensions of nanoporous alumina (NPA) membranes prepared by an anodization process and their electrochemical properties as a sensing platform using impedance spectroscopy was explored. NPA with four different pore diameters (25 nm, 45 nm and 65 nm) and lengths (5 µm to 20 µm) was used and their electrochemical properties were explored using different concentration of electrolyte solution (NaCl) ranging from 1 to 100 µM. Our results show that the impedance and resistance of nanopores are influenced by the concentration and ion species of electrolytes, while the capacitance is independent of them. It was found that nanopore diameters also have a significant influence on impedance due to changes in the thickness of the double layer inside the pores. [ABSTRACT FROM AUTHOR]

Knowledge about electrochemical and electrical properties of nanopore structures and the influence of pore dimensions on these properties is important for the development of nanopore biosensing devices. The aim of this study was to explore the influence of nanopore dimensions (diameter and length) on biosensing performance using non-faradic electrochemical impedance spectroscopy (EIS). Nanoporous alumina membranes (NPAMs) prepared by self-ordered electrochemical anodization of aluminium were used as model nanopore sensing platforms. NPAMs with different pore diameters (25–65 nm) and lengths (4–18 μm) were prepared and the internal pore surface chemistry was modified by covalently attaching streptavidin and biotin. The performance of this antibody nanopore biosensing platform was evaluated using various concentrations of biotin as a model analyte. EIS measurements of pore resistivity and conductivity were carried out for pores with different diameters and lengths. The results showed that smaller pore dimensions of 25 nm and pore lengths up to 10 μm provide better biosensing performance. [ABSTRACT FROM AUTHOR]

Electrodes fabricated using commercially available silver nanowires (AgNWs) and single walled carbon nanotubes (SWCNTs) produced sheet resistances in the range 4-24Ω◻ -1 with specular transparencies up to 82 %. Increasing the aqueous dispersibility of SWCNTs decreased the bundle size present in the film resulting in improved SWCNT surface dispersion in the films without compromising transparency or sheet resistance. In addition to providing conduction pathways between the AgNW network, the SWCNTs also provide structural support, creating stable self-supporting films. Entanglement of the AgNWs and SWCNTs was demonstrated to occur in solution prior to deposition by monitoring the transverse plasmon resonance mode of the AgNWs during processing. The interwoven AgNW/SWCNT structures show potential for use in optoelectronic applications as transparent electrodes and as an ITO replacement [ABSTRACT FROM AUTHOR]

Two helical peptides, one constrained by a covalent side-chain staple, exhibit vastly different electronic properties despite adopting essentially the same backbone conformation. High level calculations confirm that these differences are due to the additional backbone rigidity imparted by the macrocyclic constraint. [ABSTRACT FROM AUTHOR]

A new and facile method is described to prepare Janus-like nanoporous anodic aluminium oxide (AAO) membranes with distinctly different internal and external surface chemistry. [ABSTRACT FROM AUTHOR]

A new and facile method is described to prepare Janus-like nanoporous anodic aluminium oxide (AAO) membranes with distinctly different internal and external surface chemistry. [ABSTRACT FROM AUTHOR]

Highly conductive, transparent and flexible planar electrodes were fabricated using interwoven silver nanowires and single-walled carbon nanotubes (AgNW:SWCNT) in a PEDOT:PSS matrix via an epoxy transfer method from a silicon template. The planar electrodes achieved a sheet resistance of 6.6 ± 0.0 Ω/□ and an average transmission of 86% between 400 and 800 nm. A high figure of merit of 367 Ω−1 is reported for the electrodes, which is much higher than that measured for indium tin oxide and reported for other AgNW composites. The AgNW:SWCNT:PEDOT:PSS electrode was used to fabricate low temperature (annealing free) devices demonstrating their potential to function with a range of organic semiconducting polymer:fullerene bulk heterojunction blend systems. [ABSTRACT FROM AUTHOR]

In this paper, we present recent work from our group focussed on the fabrication of nanopore and nanotube arrays using self-ordered electrochemistry, and their application in several key areas including template synthesis, molecular separation, optical sensing, and drug delivery. We have fabricated nanoporous anodic aluminium oxide (AAO) with controlled pore dimensions (20-200nm) and shapes, and used them as templates for the preparation of gold nanorod/nanotube arrays and gold nanotube membranes with characteristic properties such as surface enhanced Raman scattering and selective molecular transport. The application of AAO nanopores as a sensing platform for reflective interferometric detection is demonstrated. Finally, a drug release study on fabricated titania nanotubes confirms their potential for implantable drug delivery applications. [ABSTRACT FROM AUTHOR]

Abstract: This work presents the fabrication of gold nanotube membranes (GNT) using gold deposition on porous anodic aluminum oxide (AAO) template and demonstrates the catalytic properties generated by the nanostructured gold surface. AAO membranes were prepared by electrochemical anodization of Al in 0.3M oxalic acid electrolyte. Electroless gold deposition on AAO was performed via several steps using commercially available gold plating solutions. Scanning electron microscopy (SEM) images confirm that the gold nanotubes formed inside AAO pores have characteristic nanoclustered morphology as a result of the nucleation process during gold deposition. It was found that catalytic properties of GNT membranes depend on the size of gold nanoclusters which can be controlled by pH during nucleation process. The excellent catalytic properties (catalytic rate constant k =0.132min−1) of the GNT membranes were demonstrated by testing catalytic conversion of 4-nitrophenol (4-NP) into 4-aminophenol (4-AP) in the presence of NaBH4 as a reductant. The correlation between the size of gold nanoclusters and catalytic activity was verified showing the capability of controlling and further improving catalytic properties of GNT membranes. [Copyright &y& Elsevier]

The article informs that understanding the way in which a surface responds to the solution environment allows the production of surfaces with controllable properties. The controllable activation or passivation of a surface is a key component of a number of different systems such as catalysis, biosensing, cell culture, and related areas. As the surface area-to-volume ratio become greater, the surface properties become increasingly important. The theory of acids and bases is well established and the details are readily available from any chemistry textbook but the key point for students is how to get information from the equations provided and how to interpret the graphs in terms of the theoretical equations.

Abstract: The influence of both nanotube orientation and length on the electrochemical properties of electrodes modified with single-walled carbon nanotubes was investigated. Gold electrodes were modified with either randomly dispersed or vertically aligned nanotubes to which ferrocenemethylamine was attached. Electron transfer kinetics were found to depend strongly on the orientation of the nanotube, with electron transfer between the gold electrode and the ferrocene moiety being 40 times slower through randomly dispersed nanotubes than through vertically aligned nanotubes. The difference is hypothesized to be due to electron transfer being more direct through a single tube than that with electrodes modified with randomly dispersed nanotubes. With the vertically aligned nanotubes the rate constant for electron transfer varied inversely with the mean length of the nanotubes. The results indicate there is an advantage in using aligned carbon nanotube arrays over randomly dispersed nanotubes for achieving efficient electron transfer to bound redox active species such as in the case of bioelectronic or photovoltaic devices. [Copyright &y& Elsevier]