IEE proceedings. Nanobiotechnology最新文献

Dielectrophoretic manipulation enables the positioning and orientation of DNA molecules for nanometer-scale applications. However, the dependence of the dielectrophoretic force and torque on the electric field magnitude and frequency has to be well characterised to realise fully the potential of this technique. DNA in solution is attracted to the strongest electric field gradient (i.e. the electrode edge) as a result of the dielectrophoretic force, while the dielectrophoretic torque aligns the DNA with its longest axis parallel to the electric field. In this work, the authors attached -DNA fragments (48 and 25 kilobases) to an array of gold microelectrodes via a terminal thiol bond and characterised the orientation and elongation as a function of electric field magnitude (0.1-0.8 MVm) and frequency (0.08-1.1 MHz). Maximum elongation was observed between 200 and 500 kHz for the attached DNA. Dielectrophoresis is limited by thermal randomisation at electric fields below 0.1 MVm and by electrothermal effects above 0.7 MVm. The authors conclude that dielectrophoresis can be used to manipulate surface-immobilised DNA reproducibly.

Dynamic focusing of particles can be used to centre particles in a fluid stream, ensuring the passage of the particles through a specified detection volume. This paper describes a method for focusing nanoparticles using dielectrophoresis. The method differs from other focusing methods in that it manipulates the particles and not the fluid. Experimental focusing is demonstrated for a range of different particle types, and discussed in terms of the operational limits of the device. Dynamic numerical simulations of the particle motion in the device are presented and compared with the experimental results. The potential of the device for nanoparticle control and manipulation in microfluidic chips is discussed.

Microfabrication and performance of a novel microsystem for separation, accumulation and analysis of biological micro- and nanoparticles is reported. Versatile chip functions based on dielectrophoresis and microfluidics were integrated to isolate particles from complex sample solutions such as serum. A bead-based assay for virus detection is proposed. Separation of micro- and sub-mum beads employing dielectrophoretic deflector and bandpass structures is demonstrated. Individual antibody coated beads with hepatitis A virus bound to their surface were trapped by negative dielectrophoresis in a field cage and analysed by fluorescence microscopy.

The authors present a method for separation of two latex spheres populations using dielectrophoresis (DEP) and the fluid drag force. Microelectrodes of a suitable layout are used to trap one population of spheres, while the other one is dragged away from the electrodes by the generated fluid flow. The finite difference method is implemented in C++ to calculate the potential distribution by solving Laplace's equation. From the potential distribution, the DEP force on particles is calculated. The drag force on particles due to the liquid motion is calculated from the observed fluid velocity. The experimental results are shown to be in good agreement with the numerical solution.

Carbon nanotubes are a significant addition to the emerging field of nanotube biotechnology. The biocompatibility, high structural integrity, and unique electronic and mechanical properties of carbon nanotubes complement or surpass those of self-assembled lipid nanotubes, peptide nanotubes, and template-synthesised nanotubes (metals, polymers, semiconductors, and carbons). Carbon nanotubes are candidates for a range of biomolecular applications that is likely to widen considerably in the future.

The principles of attenuation of the light intensity due to multiple reflections are realised in a planar silicon oxide (SiO(2))silicon nitride (Si(3)N(4)) waveguiding structure for the purpose of developing optical biosensors with improved sensitivity. The analysis of the experimental data shows that the large difference in refractive indices of core and cladding layers gives rise to an increase in sensitivity by a factor of 3 over previously reported structures. Composite polyelectrolyte self-assembled thin films containing cyclo-tetra-chromotropylene as an indicator and enzymes glucose oxidase or urease were employed in the superstrate as a sensing membrane. Individual enzyme reactions as well as their inhibition by pesticides were studied by monitoring the intensity of light output from the planar waveguide. The results were compatible with those obtained by conventional ultraviolet-visible absorption spectroscopy. The instrument detection limit for Imidacloprid pesticide was found to be as low as 10 ppb in concentration.

Cytochromes P450 are a large superfamily of heme-thiolate enzymes involved in the metabolism of many different organic substrates such as drugs, fatty acids and toxic compounds. The aim of this work is to analyse the binding between the cytochrome P4501A2, in solution and in gel-matrix, and its substrate (clozapine), utilising voltammetric tests. The interaction measurements were carried out using two different screen printed electrodes (rhodium-graphite and graphite-riboflavin), and the results were compared. It was demonstrated that it is possible to realise a biosensor prototype to detect the presence of clozapine indirectly by chronoamperometry.

The possibility of constructing high-density parallel computing architectures using molecular electronics technology is explored. By employing molecular computing devices, new circuitsystem integration could be realised. To clarify the proposed concept, an experimental model of a redox microarray is presented. A first experimental system for a redox microarray consists of a two-dimensional array of platinum microelectrodes to catalyse reversible reactions of redox-active molecules. Experimental results of active wave propagation in the redox microarray are presented to demonstrate the potential of molecular computing devices for creating artificially programmable reaction-diffusion dynamics for specific target applications.