Papers by Keyword: DNA Sequencing

Abstract: The glass nanopore produced by the physical method has better physical characteristics, higher strength, stronger stability, longer life and other significant features compared with the chemical method. The purpose of this paper is to study DNA sequencing (973 project) to provide experimental basis for preparation of glass capillary 5nm 3D nanochannel In this paper, we design a set of glass capillary tension system which is controlled by laser heating and linear ultrasonic motor and produced successfully the device for the preparation of nanopore below 50 nm. In addition, the use of micro droplet generation system has carried out preliminary characterization of nanopore drawn devices. Seen from the characterization, the nanopore device fabricated can indeed produce a through-hole.

Abstract: nfectious microbial pathogens constitute the largest cause of morbidity and mortality worldwide. Early diagnosis and rapid infection control measures can lead to improved outcomes, earlier discharges and reduced nosocomial infections. Conventional diagnostic methods for infectious diseases such as microscopy, culture, and immunological methods, in most cases, are not universally applicable, less sensitive and could take from days to months to complete depending on the pathogen. Molecular assays based on nucleic acids such as polymerase chain reaction (PCR) have improved the sensitivity, specificity and turn-around time in diagnostic microbiology laboratories. These tests are particularly important to detect very low levels of pathogens in clinical samples, and for organisms that have long half-lives or are non-culturable. However, individual molecular tests are available for only a limited number of the more common infectious agents. Moreover, infectious disease events arising from novel pathogens or genetic variants have significantly increased, recently, for which, routine diagnostic methods are not yet available. Therefore, molecular methods and technologies capable of detecting multiple pathogens in a single test have become available over the last few years. Although, these methods are based on the conventional nucleic acid amplification and hybridization chemistry, enhanced multiplexing capability has been achieved through innovations in nucleic acid labeling techniques, and post-amplification analytic methods and instrumentation. The availability of these test kits brought a new level of convenience to the physicians ordering practices, and to the laboratory personnel, as they require very little hands on time. However, these tests are yet unaffordable to many laboratories, and in many cases, the sensitivity is poor compared to that of single-target, real-time PCR assays. Looking into the future, the revolutionary, next generation sequencing (NGS) technology is now being considered as a potential method for rapid identification of hundreds of pathogens, in an unbiased manner, with a single test that could significantly benefit patients who are critically ill with undiagnosed disease.

Abstract: DNA sequencing by nanopore is a technique to detect DNA sequence by making the DNA strain passing through the nanopore material and measureing some characteristic parameters to determine the order of the four kinds of base-pairs. Graphene nanopore research becomes a hotspot for the DNA sequencing technology. In this paper, a kind of novel nanopore on graphene oxide is sculptured with FEB(Focused Electron Beam) to overcome the problem about the high noise for graphene nanopore. By tuning FEB parameters, e.g. the accelerating voltage, the spot number, the exposure time and the amplification factor, sub 10nm nanopores on single layer GO(Graphene Oxide) film will be achieved. At the same time, some challenges are discussed: difficult to get stable size, hard to take TEM pictures and hard to get relatively smaller size.

Abstract: A novel preconcentration method for efficient DNA sample stacking during sample introduction and injection in microchip electrophoresis is presented in this paper. The method suggests that a pair of sample stacking electrodes is designed after the double-T section. A sample stacking electrical field can be established after sample introduction inside the double-T section, so that the sample stacking procedure can be controlled accurately and efficiently. In order to test this method’s validity, a numerical model is setup using COMSOL Multiphysics software. The simulation result shows that the peak DNA concentration can be increased up to 10 fold by this method. These results demonstrate the great potential for significantly enhance DNA sequencing speed and resolution in microchip electrophoresis.

Abstract: A systematic nanoelectrode-gated electron-tunneling molecular-detection concept with potential for rapid DNA sequencing has recently been invented at Oak Ridge National Laboratory (ORNL). A DNA molecule is a polymer that typically contains four different types of nucleotide bases: adenine (A), thymine (T), guanine (G), and cytosine (C) on its phosphate-deoxyribose chain. According to the nanoelectrode-gated molecular-detection concept, it should be possible to obtain genetic sequence information by probing through a DNA molecule base by base at a nanometer scale, as if looking at a strip of movie film. The nanoscale reading of DNA sequences is envisioned to take place at a nanogap (gate) defined by a pair of nanoelectrode tips as a DNA molecule moves through the gate base by base. The rationale is that sample molecules, such as the four different nucleotide bases, each with a distinct chemical composition and structure, should produce a specific perturbation effect on the tunneling electron beam across the two nanoelectrode tips. A sample molecule could thus be detected when it enters the gate. This nanoscience-based approach could lead to a new DNA sequencing technology that could be thousands of times faster than the current technology (Sanger’s “dideoxy” protocol-based capillary electrophoresis systems). Both computational and experimental studies are underway at ORNL towards demonstrating this nanotechnology concept.