Peiming Zhang

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It has been proposed that single molecules of DNA could be sequenced by measuring the physical properties of the bases as they pass through a nanopore. Theoretical calculations suggest that electron tunnelling can identify bases in single-stranded DNA without enzymatic processing, and it was recently experimentally shown that tunnelling can sense individual(More)
Nucleosides diffusing through a 2 nm electron-tunneling junction generate current spikes of sub-millisecond duration with a broad distribution of peak currents. This distribution narrows 10-fold when one of the electrodes is functionalized with a reagent that traps nucleosides in a specific orientation with hydrogen bonds. Functionalizing the second(More)
Hybridization rates of sheared, genomic E. coli DNA in 0.14 M, pH 6.7 phosphate buffer at 65 degrees C were determined by: (1) observing the rate of absorbance decrease at 260 nm due to self-hybridization in solution; and (2) measurement of the rate of mass increase caused by hybridization between DNA in solution and DNA photografted to polystyrene. The(More)
We propose a new approach for reading the sequence of a DNA molecule passing between electrodes on a nanopore, using hydrogen bond-mediated tunneling signals. The base-electrode interaction is modeled using a nucleo-base-functionalized STM probe that is pulled away from a nucleoside monolayer. Watson-Crick recognition results in slow decay of the tunnel(More)
The human proteome has millions of protein variants due to alternative RNA splicing and post-translational modifications, and variants that are related to diseases are frequently present in minute concentrations. For DNA and RNA, low concentrations can be amplified using the polymerase chain reaction, but there is no such reaction for proteins. Therefore,(More)
Hydrogen bonding has a ubiquitous role in electron transport and in molecular recognition, with DNA base pairing being the best-known example. Scanning tunnelling microscope images and measurements of the decay of tunnel current as a molecular junction is pulled apart by the scanning tunnelling microscope tip are sensitive to hydrogen-bonded interactions.(More)
We demonstrate a method to measure surface charge density and particle height using surface plasmon resonance (SPR) detection. It is based on two facts: (1) The equilibrium height of a charged particle over a charged surface depends on the electrostatic interaction between the particle and the surface; and (2) SPR is extremely sensitive to the height of the(More)
4(5)-(2-mercaptoethyl)-1H-imidazole-2-carboxamide is a molecule that has multiple hydrogen bonding sites and a short flexible linker. When tethered to a pair of electrodes, it traps target molecules in a tunnel junction. Surprisingly large recognition-tunneling signals are generated for all naturally occurring DNA bases A, C, G, T and 5-methyl-cytosine.(More)
We have developed a chemical reagent that recognizes all naturally occurring DNA bases, a so called universal reader, for DNA sequencing by recognition tunneling in nanopores.1 The primary requirements for this type of molecules are the ability to form non-covalent complexes with individual DNA bases and to generate recognizable electronic signatures under(More)
Understanding the complexities of DNA has been a hallmark of science for over a half century, and one of the important topics in DNA research is recognizing the occurrence of mutations in the base-stack. In this article, we present a study of SNPs by direct-contact electrical measurements to a single DNA duplex. We have used short, 11- and 12-bp dsDNA to(More)