Prof. Deqiang Wang

Nanopore-based sequencers, as the fourth-generation DNA sequencing technology, have the potential to quickly and reliably sequence the entire human genome for less than $1000, and possibly for even less than $100. The single-molecule techniques used by this technology allow us to further study the interaction between DNA and protein, as well as between protein and protein. Nanopore analysis opens a new door to molecular biology investigation at the single-molecule scale. In this article, we have reviewed academic achievements in nanopore technology from the past as well as the latest advances, including both biological and solid-state nanopores, and discussed their recent and potential applications.

16 December 2016 in Nanotechnology

Journal Article

Precise fabrication of a 5 nm graphene nanopore with a helium ion microscope for biomolecule detection

Yunsheng Deng

Qimeng Huang

Yue Zhao

Daming Zhou

Cuifeng Ying

Deqiang Wang

We report a scalable method to fabricate high-quality graphene nanopores for biomolecule detection using a helium ion microscope (HIM). HIM milling shows promising capabilities for precisely controlling the size and shape, and may allow for the potential production of nanopores at wafer scale. Nanopores could be fabricated at different sizes ranging from 5 to 30 nm in diameter in few minutes. Compared with the current solid-state nanopore fabrication techniques, e.g. transmission electron microscopy, HIM is fast. Furthermore, we investigated the exposure-time dependence of graphene nanopore formation: the rate of pore expansion did not follow a simple linear relationship with exposure time, but a fast expansion rate at short exposure time and a slow rate at long exposure time. In addition, we performed biomolecule detection with our patterned graphene nanopore. The ionic current signals induced by 20-base single-stranded DNA homopolymers could be used as a basis for homopolymer differentiation. However, the charge interaction of homopolymer chains with graphene nanopores, and the conformations of homopolymer chains need to be further considered to improve the accuracy of discrimination.

1 January 2021 in International Journal of Extreme Manufacturing

Journal Article

Helium-ion-beam nanofabrication: extreme processes and applications

Shixuan He

Rong Tian

Wei Wu

Wen-Di Li

Deqiang Wang

6 November 2017 in Applied Physics Letters

Journal Article

Quantitative detection of the respective concentrations of chiral compounds with weak measurements

Linguo Xie

Xiaodong Qiu

Lan Luo

Xiong Liu

Zhaoxue Li

Deqiang Wang

In this letter, we determine the respective concentrations of glucose and fructose in the mixed chiral solution by simultaneously measuring the optical rotation angle (ORA) and the refractive index change (RIC) with weak measurements. The photonic spin Hall effect (PSHE) serves as a probe in our scheme. The measurement of ORA is based on the high sensitivity of the amplification factor to the polarization state in weak measurements. The measurement of RIC is based on the rapid variation of spin splitting of the PSHE. The measurement precision of the respective concentrations can be achieved to be 0.02 mg/ml. This method can detect traces of enantiomeric impurities and has a potential application in chiral sensing.

8 August 2016 in Applied Physics Letters

Journal Article

3D nanopore shape control by current-stimulus dielectric breakdown

Cuifeng Ying

Yuechuan Zhang

Yanxiao Feng

Daming Zhou

Deqiang Wang

Jian-Guo Tian

We propose a simple and cost-effect method, current-stimulus dielectric breakdown, to manipulate the 3D shapes of the nanochannels in 20-nm-thick SiNx membranes. Besides the precise control of nanopore size, the cone orientation can be determined by the pulse polarity. The cone angle of nanopores can be systematically tuned by simply changing the stimulus pulse waveform, allowing the gradual shape control from conical to obconical. After they are formed, the cone angle of these nanopores can be further tuned in a certain range by adjusting the widening pulse. Such size and 3D shape controllable abiotic nanopores can construct a constriction in the nanochannel and hence produce a sub-nm “sensing zone” to suit any desired bio-sensing or precise DNA sequencing. Using these conical nanopores, 20-nt ssDNA composed of homopolymers (poly(dA)20, poly(dC)20, and poly(dT)20) can be clearly differentiated by their ionic current signals.

1 March 2021 in Plant Communications

Journal Article

A solid-state nanopore-based single-molecule approach for label-free characterization of plant polysaccharides

Yao Cai

Baocai Zhang

Liyuan Liang

Sen Wang

Lanjun Zhang

Deqiang Wang

Polysaccharides are important biomacromolecules existing in all plants, most of which are integrated into a fibrillar structure called the cell wall. In the absence of an effective methodology for polysaccharide analysis that arises from compositional heterogeneity and structural flexibility, our knowledge of cell wall architecture and function is greatly constrained. Here, we develop a single-molecule approach for identifying plant polysaccharides with acetylated modification levels. We designed a solid-state nanopore sensor supported by a free-standing SiNx membrane in fluidic cells. This device was able to detect cell wall polysaccharide xylans at concentrations as low as 5 ng/μL and discriminate xylans with hyperacetylated and unacetylated modifications. We further demonstrated the capability of this method in distinguishing arabinoxylan and glucuronoxylan in monocot and dicot plants. Combining the data for categorizing polysaccharide mixtures, our study establishes a single-molecule platform for polysaccharide analysis, opening a new avenue for understanding cell wall structures, and expanding polysaccharide applications.

About Me

Dr. Deqiang Wang currently works as a Professor at the Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing. In July 2006, he received his Ph.D. from the Institute of Microelectronics, Chinese Academy of Sciences. From 2007 to 2010, he worked as a postdoctoral researcher on natural nanopores and solid nanopores at the University of Texas at Arlington (UTA) and the University of Illinois at Urbana-Champaign (UIUC); from 2010 to 2014, he worked on the fabrication of micro-nanostructures and the detection of DNA and proteins at the single-molecule scale at the IBM Watson Research Center. His main research interest is focusing on nanopore-based DNA sequencing. His research activities also include micro- and nano-fabrication and their applications. He has successfully fabricated a sub-20 nm nanopore in diameter across an 8” wafer with semiconductor processes. He trapped dsDNA inside the nanopore for a few minutes with DNA transistor devices and studied the interaction between the dsDNA with different surface properties inside the nanopore. He also successfully slowed down the average translocation velocity of DNA through a nanopore with glycerol solution and a feedback-controlled circuit.

Prof. Deqiang Wang

Prof. Deqiang Wang

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