A5015100789- Nanopore and Nanochannel Transport Studies
- Fuel Cells and Related Materials
- Membrane-based Ion Separation Techniques
- Microfluidic and Capillary Electrophoresis Applications
- Electrochemical Analysis and Applications
- Electrostatics and Colloid Interactions
- Advanced biosensing and bioanalysis techniques
- Ion-surface interactions and analysis
- stochastic dynamics and bifurcation
- Microfluidic and Bio-sensing Technologies
- Advanced Memory and Neural Computing
- Analytical Chemistry and Sensors
- Ion channel regulation and function
- Carbon Nanotubes in Composites
- Lipid Membrane Structure and Behavior
- Geophysical and Geoelectrical Methods
- Spectroscopy and Quantum Chemical Studies
- Anodic Oxide Films and Nanostructures
- Electron and X-Ray Spectroscopy Techniques
- Thermal properties of materials
- Cellular Mechanics and Interactions
- Cell Image Analysis Techniques
- Membrane Separation Technologies
- Quantum-Dot Cellular Automata
- Advancements in Semiconductor Devices and Circuit Design
University of California, Irvine
2016-2025
University of Maryland, College Park
2024
Physical Sciences (United States)
2024
The University of Texas at Austin
2024
Walker (United States)
2024
UC Irvine Health
2013-2020
Irvine University
2020
University of California System
2007-2016
Irvine Valley College
2015-2016
Utrecht University
2015
This article focuses on ion transport through nanoporous systems with special emphasis rectification phenomena. The effect of ion-current is observed as asymmetric current–voltage (I–V) curves, the current recorded for one voltage polarity higher than same absolute value opposite polarity. diode-like I–V curve indicates that there a preferential direction flow. Experimental evidence inherent to asymmetric, e.g., tapered, excess surface charge provided and discussed. fabrication operation...
We present a nanofluidic diode that at voltage range -5 to +5 V rectifies ion current with degrees of rectification reaching several hundreds. The is based on single asymmetric nanopore whose surface was patterned so sharp boundary between positively and negatively charged regions created. This defines zone enriched positive negative ions or creates depletion zone. principle operation the analogous bipolar semiconductor diode.
We present a synthetic nanodevice, which transports potassium ions against their concentration gradient if stimulated with external field fluctuations. It consists of single, conical pore, created in thin polyethylene terephthalate film. The pumping mechanism is similar to one longitudinally oscillating deterministic ratchets.
There is increasing interest in the concept of using nanopores as sensing elements biosensors. The nanopore most often used α-hemolysin protein channel, and sensor consists a single channel embedded within lipid bilayer membrane. An ionic current passed through analyte species are detected transient blocks this associated with translocation channel−stochastic sensing. While an extremely promising paradigm, it would be advantageous to eliminate very fragile membrane perhaps replace biological...
Ion channels are protein pores that span cell membranes and open close in response to stimuli like changes the transmembrane potential, binding of a ligand, or mechanical stress. When open, ions pass through pore, hence across membrane, when closed, ion-transport is precluded. Hence, these nanodevices have current-rectification function. There intense research effort aimed at understanding molecular-level mechanism for this One approach elucidating construct simple abiotic system mimics...
Abstract Purpose: Ion channel activity is involved in several basic cellular behaviors that are integral to metastasis (e.g., proliferation, motility, secretion, and invasion), although their contribution cancer progression has largely been ignored. The purpose of this study was investigate voltage-gated Na+ (VGSC) expression its possible role human breast cancer. Experimental Design: Functional VGSC investigated cell lines by patch clamp recording. directional endocytosis, invasion...
There has been an increasing interest in single nanochannel ionic devices, such as filters that control the type of transported ions and diodes rectify flow. In this article, we theoretically investigate importance dimensions, surface charge, electrolyte concentration, applied bias on nanopore performance. We compare numerical solutions Poisson, Nernst−Planck (PNP), Navier−Stokes (NS) equations with their one-dimensional, analytical approximations. show by decreasing length nanopore, current...
Recently reported nanofluidic diodes with highly nonlinear current−voltage characteristics offer a unique possibility to construct different biosensors. These sensors are based on local changes of the surface charge walls single conical nanopores induced by binding an analyte. The analyte can be detected as change ion-current rectification defined ratio currents for voltages one polarity, and opposite polarity. In this article, we provided both modeling experimental studies various...
We show that diffusion currents for a membrane containing single conical nanopore with fixed surface charge and small enough opening diameter depend on the concentration gradient direction. interpret results based effect of salt thickness electrical double layer within associated nanopore's distribution electric fields inside pore. The experimental observations are described by diffusional model Smoluchowski-Nernst-Planck equation.
Nanopores exhibit a set of interesting transport properties that stem from interactions the passing ions and molecules with pore walls. are used, for example, as ionic diodes transistors, biosensors, osmotic power generators. Using nanopores is however disadvantaged by their high resistance, small switching currents in nA range, low generated, signals can be difficult to distinguish background. Here, we present mesopore conductance reaching μS rectifies ion current salt concentrations 1 M....
The advancement of nanofluidic applications will require the identification materials with high-conductivity nanoscale channels that can be readily obtained at massive scale. Inspired by transpiration in mesostructured trees, we report a membrane consisting densely packed cellulose nanofibers directly derived from wood. Numerous nanochannels are produced among an expansive array one-dimensional nanofibers. abundant functional groups enable facile tuning surface charge density via chemical...
A nanopore decorated with crown ether and DNA is selective to potassium ions over sodium at concentrations up 1 M.
Synthetic sensors use molecular recognition events in nanometer-scale pores for selective detection of proteins, nucleotides, and drugs.
There is considerable interest in developing chemical devices that mimic the function of biological ion channels. We recently described such a device, which consisted single conically shaped gold nanotube embedded within polymeric membrane. This device mimicked one key functions voltage-gated channels: ability to strongly rectify ionic current flowing through it. The data obtained were interpreted using simple electrostatic model. While details are still being debated, it clear...
The preparation of a bipolar ionic transistor based on single hourglass-shaped nanopore with tailored surface charge is shown. narrow opening the pore was between 2 and 6 nm. gate in our device on/off behavior are controlled chemically by changing walls. This accomplished pH concentrations electrolyte.
Nanotubes can selectively conduct ions across membranes to make ionic devices with transport characteristics similar biological ion channels and semiconductor electron devices. Depending on the surface charge profile of nanopore, ohmic resistors, rectifiers, diodes be made. Here we show that a uniformly charged conical nanopore have all these properties by changing species their concentrations each side membrane. Moreover, cation versus anion selectivity pores changed. We find polyvalent...
We report here the first example of abiotic resistive-pulse sensing a molecular (as opposed to particle or macromolecular) analyte. This was accomplished by using conically shaped nanopore prepared track-etch method as element. It is possible sense analyte because small diameter opening conical (∼4.5 nm) comparable molecule (∼2 nm).
We have fabricated a voltage sensor in the form of conically shaped nanopore polyethylene terephthalate (PET) foil. The pore is produced by irradiation foil with single heavy ion and subsequent etching alkaline solution. resulting functions as gate rectifies current due to changes its diameter an electrical field. Ion currents through show voltage-dependent fluctuations, whose kinetics are similar voltage-gated biological channels pores.
Recently reported experimental and theoretical studies of nanofluidic nonlinear devices, such as bipolar unipolar ionic diodes, have yet to answer the question about possibility their further miniaturization. In this Article, we theoretically investigate effects size reduction, applied bias, solution strength in devices. We compare numerical solutions Poisson, Nernst−Planck (PNP), Navier−Stokes (NS) equations with one-dimensional, analytical approximations. demonstrate that contribution...