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.

No abstract

No abstract

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.

No abstract

Helium ion beam (HIB) technology plays an important role in the extreme fields of nanofabrication. This paper reviews the latest developments in HIB technology as well as its extreme processing capabilities and widespread applications in nanofabrication. HIB-based nanofabrication includes direct-write milling, ion beam-induced deposition, and direct-write lithography without resist assistance. HIB nanoscale applications have also been evaluated in the areas of integrated circuits, materials sciences, nano-optics, and biological sciences. This review covers four thematic applications of HIB: (1) helium ion microscopy imaging for biological samples and semiconductors; (2) HIB milling and swelling for 2D/3D nanopore fabrication; (3) HIB-induced deposition for nanopillars, nanowires, and 3D nanostructures; (4) additional HIB direct writing for resist, graphene, and plasmonic nanostructures. This paper concludes with a summary of potential future applications and areas of improvement for HIB extreme nanofabrication technology.

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.

Transition-metal dichalcogenides (TMDs), including molybdenum disulfide (MoS2) and tungsten disulfide (WS2), with appealing properties have recently become promising alternatives to graphene with semimetal and low on/off current ratio properties as the sensing channel in field-effect transistor (FET) biosensors. However, the efficiency of DNA-based FET devices strongly depends on how DNA probes are tethered to the nanomaterial channels. As against covalent attachment, simple DNA physisorption has become increasingly popular, and a DNA sequence with strong affinity for nanomaterials is still highly sought after. Recently, poly-cytosine (poly-C) DNA was found to be strongly adsorbed to many common nanomaterials, including WS2. Herein, a diblock DNA probe containing a (poly-C) (C15) was used to attach to a chemical vapor deposition (CVD)-grown monolayer WS2 surface; meanwhile, the target complementary DNA (cDNA) was hybridized to the other block of the DNA probe. The biosensor developed following this strategy led to a limit of detection down to 3 aM within a concentration range spanning over approximately 7 orders of magnitude (10–16 to 10–9 M), which was lower than those of the previously reported TMDs and a good competitor to graphene FET DNA biosensors. Moreover, the proposed WS2 FET DNA biosensor showed high specificity capable of distinguishing the cDNA from non-cDNA, one-base mismatched DNA, two-base mismatched DNA, and three-base mismatched DNA, making our strategy an exciting avenue for disease diagnosis. The authors are convinced that this work extends the CVD synthesis of WS2 and its promise in biosensing application-based FETs.