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...

ADVERTISEMENT RETURN TO ARTICLES ASAPPREVReviewNEXTRecent Developments in Single-Entity ElectrochemistryL. ZhangL. ZhangDepartment of Chemistry, Texas A&M University, College Station, 77845, United StatesMore by L. ZhangView Biography, O. J. WahabO. WahabDepartment WahabView Biographyhttps://orcid.org/0000-0003-4280-9089, A. JallowA. JallowDepartment JallowView Biographyhttps://orcid.org/0000-0003-2173-4137, Z. O'DellZ. O'DellDepartment Temple Philadelphia, Pennsylvania 19122, O'DellView...

Au colloids in the 2−3-nm size regime were prepared by situ reduction of HAuCl4 presence poly(amidoamine) dendrimers. The dendrimers encapsulate colloids, imparting stability to aqueous colloidal solutions. nanocomposite materials can be isolated precipitation. dendrimer generation used synthesis controls resultant colloids: lower-generation give rise larger colloids. characterized infrared and UV−vis spectroscopy transmission electron microscopy.

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).

There is increasing interest in using nanopores synthetic membranes as resistive-pulse sensors for molecular and macromolecule analytes. In general, this method entails measuring current pulses associated with translocation of the analyte through nanopore sensor element. A key challenge sensing paradigm building selectivity into protocol so that target can be distinguished from other species might present sample. We show here accomplished a protein by adding to solution an antibody...

Single-component monolayers of dendrimers and two-component consisting n-alkanethiols immobilized on Au substrates are described. prepared by exposing an substrate to ethanolic solutions amine- or hydroxy-terminated polyamidoamine (PAMAM) dendrimers. The resulting highly stable nearly close-packed for dendrimer generations ranging from 4 8 (G4−G8). Electrochemical ac-impedance measurements indicate that the surface is very porous toward electroactive redox couple Fe(CN)63-/4-....

In this paper, we describe resistive-pulse sensing of two large DNAs, a single-stranded phage DNA (7250 bases) and double-stranded plasmid (6600 base pairs), using conically shaped nanopore in track-etched polycarbonate membrane as the element. The had small-diameter (tip) opening 40 nm large-diameter (base) 1.5 μm. DNAs were detected resistive-pulse, sometimes called stochastic sensing, method. This entails applying transmembrane potential difference monitoring resulting ion current flowing...

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTStructural Distortion of Dendrimers on Gold Surfaces: A Tapping-Mode AFM InvestigationAndreas Hierlemann, Joseph K. Campbell, Lane A. Baker, Richard M. Crooks, and Antonio J. RiccoView Author Information Department Chemistry, Texas & M University P.O. Box 300012, College Station, 77842-3012 Sandia National Laboratories Albuquerque, New Mexico 87185-1425 Cite this: Am. Chem. Soc. 1998, 120, 21, 5323–5324Publication Date (Web):May 13,...

Electrocatalytic reduction reactions (i.e., the hydrogen evolution reaction (HER) and oxygen reaction) at individual, faceted Au nanocubes (NCs) nano-octahedra (ODs) expressing predominantly {100} {111} crystal planes on surface, respectively, were studied by nanoscale voltammetric mapping. Cyclic voltammograms collected individual nanoparticles (NPs) with scanning electrochemical cell microscopy (SECCM) correlated particle morphology imaged electron microscopy. Nanoscale measurements from a...

Nafion has found utility in a wide variety of applications, particularly as the most commonly used electrolyte membrane fuel cell technology. Despite decades characterization by X-ray Photoelectron Spectroscopy (XPS), dispute exists within literature over proper assignment oxygen binding energies from ether and sulfonate functional groups present Nafion. Here, we have employed highly oriented pyrolytic graphite (HOPG) an internal standard to calibrate all XPS spectra are able correlate C1s,...

We describe ion distribution and the current-voltage (i-V) response of nanopipettes at different probe-to-substrate distances (Dps) as simulated by finite-element methods. Results suggest electrostatic interactions between a charged substrate nanopipette dominate electrophoretic transport through when Dps is within 1 order magnitude Debye length (∼10 nm for mM solution employed in simulation). Ion current rectification (ICR) permselectivity associated with neutral or can be reversibly...

Mg battery operates with Chevrel phase (Mo6S8, ∼1.1 V vs Mg) cathodes that apply Grignard-based or derived electrolytes, which allow etching of the passivating oxide coating forms at magnesium metal anode. Majority electrolytes studied to date are focused on developing new synthetic strategies achieve a better reversible deposition. While most these contain chloride as component, and there is lack literature investigates fundamental role in electrolytes. Further, ease preparation potential...

The conversion of CO2 into value-added products is a compelling way storing energy derived from intermittent renewable sources and can bring us closer to closed-loop anthropogenic carbon cycle. ability synthesize nanocrystals well-defined structure composition has invigorated catalysis science with the promise that selectively express most favorable sites for efficient catalysis. performance nanocrystal catalysts reduction reaction (CO2RR) typically evaluated ensembles, which returns an...

We have used the z-scan technique at a wavelength (532 nm) near transmission window of bulk gold to measure nonlinear absorption coefficient continuous approximately 50-Å-thick films, deposited onto surface-modified quartz substrates. For highly absorbing media such as metals, we demonstrate that determination either real or imaginary part third-order susceptibility requires measurement both and refraction, i.e., open- closed-aperture z scans must be performed. Closed-aperture did not yield...

A dendrimer-modified nanopipette is used to detect hybridization of a specific DNA sequence through evaluation the extent rectification ion currents observed in measured current–voltage response.

Here we report syntheses and study of composite solid polymer electrolytes (SPEs) based on a poly(ethylene glycol)-in-Li triflate material that contains an organic-inorganic (OIC) in which boron species are incorporated into silica network. The structure properties the SPEs synthesized were characterized by scanning transmission electron microscopy (STEM), 29Si, 11B 13C state NMR, differential calorimetry, impedance spectroscopy. STEM allowed assessment OIC particles their native environment...

At the nanoscale, methods to measure surface charge can prove challenging. Herein we describe a general method report through measurement of ion current rectification nanopipette brought in close proximity charged substrate. This is able discriminate between cationic and anionic substrates when within distances from ten hundreds nanometers surface. Further studies pH dependence on observed support surface-induced mechanism demonstrate ability further nominally uncharged surfaces. could find...