IEE proceedings. Nanobiotechnology最新文献

Systems biology, i.e. quantitative, postgenomic, postproteomic, dynamic, multiscale physiology, addresses in an integrative, quantitative manner the shockwave of genetic and proteomic information using computer models that may eventually have 10(6) dynamic variables with non-linear interactions. Historically, single biological measurements are made over minutes, suggesting the challenge of specifying 10(6) model parameters. Except for fluorescence and micro-electrode recordings, most cellular measurements have inadequate bandwidth to discern the time course of critical intracellular biochemical events. Micro-array expression profiles of thousands of genes cannot determine quantitative dynamic cellular signalling and metabolic variables. Major gaps must be bridged between the computational vision and experimental reality. The analysis of cellular signalling dynamics and control requires, first, micro- and nano-instruments that measure simultaneously multiple extracellular and intracellular variables with sufficient bandwidth; secondly, the ability to open existing internal control and signalling loops; thirdly, external BioMEMS micro-actuators that provide high bandwidth feedback and externally addressable intracellular nano-actuators; and, fourthly, real-time, closed-loop, single-cell control algorithms. The unravelling of the nested and coupled nature of cellular control loops requires simultaneous recording of multiple single-cell signatures. Externally controlled nano-actuators, needed to effect changes in the biochemical, mechanical and electrical environment both outside and inside the cell, will provide a major impetus for nanoscience.

This article reviews the progress in the field of polyelectrolyte multilayer membranes with special attention to freestanding membranes. These can be prepared both in the form of hollow capsules and as flat membrane sheets. While (bio) functionality, or bioactivity as it is known, from solid supported multilayers is maintained, additional applications arise for the freestanding membranes in the fields of encapsulation, separation and micromechanics. The production processes and functionalities achieved for capsules and flat sheets. The integration of membranes into larger scale structures is essential for their use and an overview of existing strategies is given. In particular, the way in which arrays of micro-compartments can be built up is shown, and their potential for sensing and combinatorial chemistry discussed. Recent results on the applications of such systems as membrane sensors in the case of flat membrane sheets are also discussed.

Efforts were made to realise a two-dimensional, on-line-coupled isotachophoresis-capillary zone electrophoresis system. The electrophoretic behaviour of gold nanoparticles was investigated with the idea that they could be used to improve the control of this electrophoretic set-up. The well-known citrate-ligated gold nanoparticles were not suitable for this application, because the ligand was desorbed, and the nanoparticle solutions were degraded. Therefore mercaptocarboxylic acids were used, because the chemisorption of thiols on the gold surface was improved. Isotachophoretic measurements were carried out with these nanoparticles. A size-dependent electrophoretic mobility was found according to theoretical predictions, and the surface and zeta-potential were discussed for the small particle range. A new method for concentration measurements of nanoparticles is presented by means of isotachophoresis.

The utilisation of plasmonic effects in metallic nanostructures is gaining importance for applications in molecular sensing. Of special interest is the local field enhancement effect, which enables surface-enhanced Raman scattering and significantly boosts the sensitivity of the Raman technique. For in vivo biological research, the ability to excite the resonance of localised surface plasmon-polaritons within the biological window is often desired. A new nanostructure called the nano-crescent is introduced and exhibits strong plasmonic activities within the biological window using a novel intra-particle plasmonic coupling scheme.

A solid-phase sandwich fluorescence immunoassay using nanocrystals of a fluorogenic precursor, fluorescein diacetate (FDA), conjugated with monoclonal antibodies for the detection of C-reactive protein (CRP), is described. FDA nanocrystals were coated with distearoylglycerophosphoethanolamine (DSPE), modified with amino(poly(ethylene glycol))(PEG(2000)-Amine) as an interface for coupling biomolecules. CRP was chosen as a model analyte because of its widely accepted role as a marker for acute inflammation and prospective heart failure. A low limit of detection (1.10 microg l(-1)) and high precision (CV = 2.72-9.48%) were achieved. Following the immunoreaction, the monoclonal anti-CRP conjugated nanocrystals were released by hydrolysis and dissolution instigated by the addition of a large volume of organic solvent-sodium hydroxide mixture. Using human serum samples from 66 patients with high heart attack risk and 19 healthy blood donors, this CRP fluorescence immunoassay showed a good correlation to the commercially available, turbidimetric immunoassay for CRP. This result was corroborated by the Bland-Altman plot that showed a mean difference between the two methods of only 0.36+/-1.46 mg l(-1). The study demonstrates that the organic fluorogenic FDA nanocrystals can be applied for the detection of CRP, which is a clinically interesting plasma protein with a low limit of detection.

Nucleic acids are well suited to serve as biosensors for the fast and reliable detection of small organic molecules, such as a number of metabolites or antibiotics, specific nucleic acid sequences, peptides, proteins or metal ions. One of the main advantages of using nucleic acids as biosensors is that they can be modulated to respond allosterically to specific effectors. Thus molecular recognition is transformed directly into a catalytic process with observable results. In particular, catalytic RNA structures, such as the hammerhead and hairpin ribozymes, have been used for biosensor engineering. The review reports on the function mode of nucleic acid biosensors and introduces recent developments and applications in the field.

The study of ion channels and other membrane proteins and their potential use as biosensors and drug screening targets require their reconstitution in an artificial membrane. These applications would greatly benefit from microfabricated devices in which stable artificial lipid bilayers can be rapidly and reliably formed. However, the amount of protein delivered to the bilayer must be carefully controlled. A vesicle fusion technique is investigated where composite ion channels of the polyene antibiotic nystatin and the sterol ergosterol are employed to render protein-carrying vesicles fusogenic. After fusion with an ergosterol-free artificial bilayer, the nystatin-ergosterol channels do not dissociate immediately and thus cause a transient current signal that marks the vesicle fusion event. Experimental pitfalls of this method were identified, the influence of the nystatin and ergosterol concentration on the fusion rate and the shape of the fusion event marker was explored, and the number of different lipid species was reduced. Under these conditions, the -amyloid peptide could be delivered in a controlled manner to a standard planar bilayer. Additionally, electrical recordings were obtained of vesicles fusing with a planar lipid bilayer in a microfabricated device, demonstrating the suitability of nystatin-ergosterol modulated vesicle fusion for protein delivery within microsystems.

A construct based on the electrostatic layer-by-layer self assembly technique has been fabricated, to be used as a tailored device to encourage nerve regeneration. A multilayered nanocoating composed of three precursor bilayers of cationic poly(dimethyldiallylammonium) chloride (PDDA) and anionic poly(styrenesulfonate) (PSS), followed by bilayers of poly-D-lysine (PDL) and antibody specific to transforming growth factor 1 (anti-TGF-1), has been deposited on HYAFF 11. The assembly process has been monitored by quartz crystal microbalance (QCM) for its characterisation and then it has been used on HYAFF 11. Structural studies of the resulting multilayers confirmed stepwise deposition of anti-TGF-1, with an average layer thickness of 2.2+/-0.2 nm and an average surface density of 0.36+/-0.03 mug cm(-2). Scanning electron microscopy has been used to characterise multilayer uniformity. Finally, the immunological activity of the multilayered structure has been assessed. The results show that anti-TGF-1 can be included in its active form in a predetermined multilayered structure onto HYAFF 11 with quantitative control of layer thickness and weight, providing a high tool with great potential in tissue engineering.

The similarity in stability characteristics between multiscale circular cylindrical structures is revealed. Two detailed structures are explored. One is the circular cylindrical shell on an engineering scale, and another is the circular cylindrical lipid bilayer vesicle on a micro- or nanoscale. The critical stability of the vesicle acted on by uniformly distributed radial pressure is analysed. The critical load of the vesicle is derived and compared with that of the thin shell. The astonishing similarity between them is disclosed. The possible applications of such similarity to biophysics, biology and biomedicine are presented.

Nanofluidic channel arrays, which have a width of about 40 nm, depth of 60 nm and length of 50 mum, were created using a focused-ion-beam milling instrument on a silicon nitride film swiftly and exactly, as is necessary. Stained -DNA molecules were put inside these sub-100 nm conduits by capillary force and they were stretched and transferred along these conduits, which were dealt with activating reagent Brij aqueous solution in advance. The movements of DNA molecules in these channels were discussed. These nano-structure channels may be useful in the study and analysis of the statics as well as the dynamics of single biomolecules.