IEE proceedings. Nanobiotechnology最新文献

Novel biochemical sensors consisting of rotating chains of microscale paramagnetic particles have been proposed that would enable convenient, sensitive analyte detection. Predicting the dynamics of these particles is required to optimise their design. The results of lattice Boltzmann (LB) and particle dynamics (PD) simulations are reported, where the LB approach provides a verified solution of the complete Navier-Stokes equations, including the hydrodynamic interactions among the particles. On the other hand, the simpler PD approach neglects hydrodynamic interactions, and does not compute the fluid motion. It is shown that macroscopic properties, like the number of aggregated particles, depend only on the drag force and not on the total hydrodynamic force, making PD simulations yield reasonably accurate predictions. Relatively good agreement between the LB and PD simulations, and qualitative agreement with experimental data, are found for the number of aggregated particles as a function of the Mason number. The drag force on a rotating cylinder is significantly different from that on particle chains calculated from both simulations, demonstrating the different dynamics between the two cases. For microscopic quantities like the detailed force distributions on each particle, the complete Navier-Stokes solution, here represented by the LB simulation, is required.

The advantages of integrating microfluidics into photonics-based biosensing for fabricating microreactor type lab-on-a-chip devices carries a lot of advantages, such as smaller sample volume handling, controlled drug delivery and high throughput diagnosis, which is useful for in situ medical diagnosis and point-of-care (POC) testing. A hybrid integrated optical microfluidic system has been developed for the study of single molecules and enzymatic reactions. The method of optical absorption has been employed for biosensing and the feasibility of absorption-based detection on the microfluidic platform has been demonstrated using horseradish peroxidase and hydrogen peroxide, as an example. The results show that the device is useful for the analysis of both the individual chemical specimen and also the study of chemical and biological reaction between two reacting species. The hybrid integration of microfluidics and optical ensembles thus forms the basis for developing the microreactor type lab-on-a-chip device, which would have several important applications in the area of nanobiotechnology.

The nanomechanical properties of the multilayer elytra cuticle of the dung beetle (Copris ochus Motschulsky) were investigated in the vertical and transverse directions using a nano-indenter. The reduced modulus Ev and hardness Hv of the surface cuticle in the vertical direction obtained by nano-indentation were 3.54+/-0.12 GPa and 0.20+/-0.01 GP, respectively. The nano-indentation result showed that the reduced modulus E(t) and hardness Ht of each layer were gradually reduced from the outer layer to the inner layer in the transverse direction. Ev was less than the largest Et presented at the outer layer (7.06+/-0.54 GPa). It was supposedly formed as a result of the composite effect of the multilayer. Without consideration of the anisotropy of chitin, an experimental model was proposed to describe the nanomechanical properties of the elytra cuticle.

Newly developed fast-scanning atomic force microscopy (AFM) allows the dissection of molecular events such as DNA-enzyme reactions at the single-molecule level. With this novel technology, a model is proposed of the DNA cleavage reaction by a type IIP restriction endonuclease ApaI. Detailed analyses revealed that ApaI bound to DNA as a dimer and slid along DNA in a one-dimensional diffusion manner. When it encountered a specific DNA sequence, the enzyme halted for a moment to digest the DNA. Immediately after digestion, the ApaI dimer separated into two monomers, each of which remained on the DNA end and then dissociated from the DNA end. Thus, fast-scanning AFM is a powerful tool to aid the understanding of protein structures and dynamics in biological reactions at the single-molecule level in sub-seconds.

A novel microfluidic sensor for measuring dynamic gas-liquid interfacial tension is reported. The device consists of a microfluidic chip with a microchannel network and an optical detection system. The sample is introduced into a main channel, while air is injected through a T-junction. Owing to the fixed flow rate ratio used for the sensor, surface tension is the only parameter determining bubble formation frequency, which can be measured by optical detection. Although the bubble is represented by a pulse in the output signal, the formation frequency is simply the frequency of the output signal. Measurements were carried out for aqueous solutions with different concentrations of the ionic surfactant cetyl trimethyl ammonium bromide. Surface tensions of these solutions were calibrated with a commercial tensiometer. The measurement results show a clear relationship between surface tension and formation frequency. The sensor can be used to identify the critical micelle concentration of the surfactant. The sensor potentially allows the use of a minute amount of sample compared with the relatively large amount required for existing commercial systems.

Porous materials are potential candidates for applications in various fields, such as bionanotechnology, gas separation, catalysts and micro-electronics. In particular, their applications in bionanotechnology include biosensors, biomedical implants and microdevices, biosupporters, bio-encapsules, biomolecule separations and biomedical therapy. All these bionanotechnology applications utilise the shape, size and size distribution of pores in porous materials. Therefore the controlled creation of pores with desired shape, size and size distribution is most important in the development of nanoporous materials. Accordingly, the accurate evaluation of pore structure is necessary in the development of nanoporous materials and their applications. This article reviews recent developments in analytical techniques to characterise the pore structures of nanoporous materials.

The paper presents the characterisation of a continuous paramagnetic capture (PMC) mode magnetophoretic microseparator for separating red and white blood cells from whole blood based on their native magnetic properties. The PMC microseparator separates the blood cells using a high-gradient magnetic separation method without the use of additives such as magnetic tagging. The microseparator is fabricated using microfabrication technology, enabling the integration of micro-scale magnetic flux concentrators in an aqueous micro-environment. Experimental results show that the PMC microseparator can continuously separate out 91.1% of red blood cells from whole blood within 5 min, using an external magnetic flux of 0.2 T from a permanent magnet. Monitoring of white blood cells dyed with a fluorescent probe shows that 87.7% of white blood cells are separated out by the 0.2 T external magnetic flux applied to the PMC microseparator.

We present an example of the use of self-assembly of biomolecules to create nanostructured building blocks. The resulting individual compartments can be tailored to fulfil specific functions: catalysis of a chemical reaction in a confined environment, detection on a molecular level and feedback with the outside. For example, such individually designed components can be assembled to build up macroscopic chemically active filters. The main component is membrane channels acting as molecular sieves, able to control the permeation across the capsule wall. We introduce briefly a new microdevice to characterise membrane channels with a future potential for high-throughput screening of channel properties based on automation, parallelisation and the use of microfluidics. Subsequently, we outline a possible application for channel-forming proteins: encapsulation of charged polymers or proteins into liposomes and restriction of diffusion through transmembrane channels to small ions, creating a Donnan potential. This Donnan potential can be used for external manipulation of nanocontainers by coupling of the capsule to an external electric field, or for the selective uptake of small charged molecules into the capsule.

We describe how infrared spectroscopy of dry films (IRDF) can provide diagnostic information, and how we expect integration with laminar fluid diffusion interface (LFDI) sample pre-processing to generate new analytical and diagnostic tests. LFDI pre-processing provides sample clean-up and analyte separation. The sensitivity of IRDF to certain analytes is enhanced through the depletion of sample constituents that otherwise obscure relevant spectral features, permitting the deposition of films with larger sample volumes and, hence, of greater effective optical pathlength for the targeted analytes. An integrated LFDI-IRDF technology holds promise both as a method for rapid point-of-care quantitative analysis of biological fluids and as the engine of discovery for a wide range of novel diagnostic methods based upon metabolic profiling. In particular, successful integration will provide a versatile and cost effective technology platform that will allow for the accurate quantification of low-concentration analytes that are otherwise inaccessible and will provide the basis for diagnostic and prognostic methods that would otherwise be impossible. The specific question addressed by the proof-of-concept study summarised here is whether the spectra of LFDI processed samples can provide analytical methods that are more accurate than otherwise possible without LFDI pre-processing. The enrichment of serum creatinine is accomplished, with subsequent enhancement of its spectral contribution permitting quantification of this clinically important analyte beyond that achievable with no pre-processing. Finally, to illustrate the potential in diagnostic applications, two recently initiated studies are outlined, one involving chronic kidney disease and the other for chronic and acute coronary artery disease.