Recent developments in nanopore sequencing have inspired new concepts in precision medicine but limited in throughput. By optically encoding calcium flux from an array of nanopores, parallel measurements from hundreds of nanopores were reported, while lateral drifts of biological nanopores set obstacles for signal processing. In this paper, optical single-channel recording (oSCR) serves to track nanopores with high precision and a general principle of nanopore motion kinetics is quantitatively investigated. By finely adjusting the osmosis-oriented interactions between the lipid/substrate interfaces, motions of nanopores could be controllably restricted. Improved signal-to-noise ratio is observed from motion-restricted nanopores, which is experimentally demonstrated. To systematically evaluate oSCR with asymmetric salt concentrations, a finite element method simulation is established. oSCR with an array of immobilized nanopores suggests new strategies for sequencing DNA by microscopic imaging in high throughput and is widely applicable to the investigation of other transmembrane proteins.

ZIF-8 crystals grow from SWCNT sidewalls to form a microporous, electrically conductive composite.

Traditional chemical sensing methodologies have typically relied on the specific chemistry of the analyte for detection. Modifications to the local environment surrounding the sensor represent an alternative pathway to impart selective differentiation. Here, we present the hybridization of a 2-D metal organic framework (Cu3(HHTP)2) with single-walled carbon nanotubes (SWCNTs) as a methodology for size discrimination of carbohydrates. Synthesis and the resulting conductive performance are modulated by both mass loading of SWCNTs and their relative oxidation. Liquid gated field-effect transistor (FET) devices demonstrate improved on/off characteristics and differentiation of carbohydrates based on molecular size. Glucose molecule detection is limited to the single micromolar concentration range. Molecular Dynamics (MD) calculations on model systems revealed decreases in ion diffusivity in the presence of different sugars as well as packing differences based on the size of a given carbohydrate molecule. The proposed sensing mechanism is a reduction in gate capacitance initiated by the filling of the pores with carbohydrate molecules. Restricting diffusion around a sensor in combination with FET measurements represents a new type of sensing mechanism for chemically similar analytes.

Non-invasive detection and quantification of the stress hormone cortisol not only provides an assessment of stress level but also enables close monitoring of mental and physical health. Here, we report two types of field-effect transistors (FETs) based on semiconducting single-walled carbon nanotubes (sc-SWCNTs) as selective cortisol sensors. In one FET device configuration, cortisol antibody is directly attached to sc-SWCNTs. In the other, gold nanoparticles (Au NPs) are used as linkers between the antibody and the sc-SWCNTs to enhance the device conductance. We fabricated and characterized both device configurations to investigate how the nanomaterial interface to cortisol antibody influences the biosensor performance. We tested the sensors in artificial sweat and compared these two types of sensors in terms of limit of detection and sensitivity, and the results indicate that direct binding between antibody and sc-SWCNTs yields better biosensor characteristics.