An integrated system for optical and electrical detection of single molecules/particles inside a solid-state nanopore

2015 ◽  
Vol 184 ◽  
pp. 85-99 ◽  
Author(s):  
Xin Shi ◽  
Rui Gao ◽  
Yi-Lun Ying ◽  
Wei Si ◽  
Yunfei Chen ◽  
...  
Keyword(s):  
Single Molecule ◽  
Detection System ◽  
Single Molecules ◽  
Ionic Current ◽  
Dark Field ◽  
Integrated System ◽  
High Temporal Resolution ◽  
Label Free ◽  
Electrical Detection ◽  
Current Detection

Nanopore techniques have proven to be useful tools for single-molecule detection. The combination of optical detection and ionic current measurements enables a new possibility for the parallel readout of multiple nanopores without complex nanofluidics and embedded electrodes. In this study, we developed a new integrated system for the label-free optical and electrical detection of single molecules based on a metal-coated nanopore. The entire system, containing a dark-field microscopy system and an ultralow current detection system with high temporal resolution, was designed and fabricated. An Au-coated nanopore was used to generate the optical signal. Light scattering from a single Au-coated nanopore was measured under a dark-field microscope. A lab-built ultralow current detection system was designed for the correlated optical and electrical readout. This integrated system might provide more direct and detailed information on single analytes inside the nanopore compared with classical ionic current measurements.

Single-Molecule Electrical Detection with Real-Time Label-Free Capability and Ultrasensitivity

Small Methods ◽  
2017 ◽  
Vol 1 (5) ◽  
pp. 1700071 ◽  
Author(s):  
Chunhui Gu ◽  
Chuancheng Jia ◽  
Xuefeng Guo
Keyword(s):  
Real Time ◽  
Single Molecule ◽  
Label Free ◽  
Electrical Detection

Electrical Detection of Protein Biomarkers Using Nanoneedle Biosensors

2012 ◽  
Vol 1414 ◽  
Author(s):  
Rahim Esfandyarpour ◽  
Hesaam Esfandyarpour ◽  
Mehdi Javanmard ◽  
James S. Harris ◽  
Ronald W. Davis
Keyword(s):  
Physical Adsorption ◽  
Ionic Current ◽  
Microfluidic Channel ◽  
Protein Detection ◽  
High Sensitivity ◽  
Receptor Protein ◽  
Label Free ◽  
Electrical Detection ◽  
Protein Biomarkers ◽  
Impedance Modulation

Abstract:Here we present the development of an array of electrical nano-biosensors in a microfluidic channel, called Nanoneedle biosensors. Then we present the proof of concept study for protein detection. A Nanoneedle biosensor is a real-time, label-free, direct electrical detection platform, which is capable of high sensitivity detection, measuring the change in ionic current and impedance modulation, due to the presence or reaction of biomolecules such as proteins or nucleic acids. We show that the sensors which have been fabricated and characterized for the protein detection. We have functionalized Nanoneedle biosensors with receptors specific to a target protein using physical adsorption for immobilization. We have used biotinylated bovine serum albumin as the receptor and sterptavidin as the target analyte. The detection of streptavidin binding to the receptor protein is also presented.

scholarly journals A label-free approach to detect ligand binding to cell surface proteins in real time

2018 ◽  
Author(s):  
Verena Burtscher ◽  
Matej Hotka ◽  
Yang Li ◽  
Michael Freissmuth ◽  
Walter Sandtner
Keyword(s):  
Ligand Binding ◽  
Real Time ◽  
Single Molecule ◽  
Membrane Capacitance ◽  
Surface Proteins ◽  
Displacement Current ◽  
High Temporal Resolution ◽  
Label Free ◽  
Single Molecule Level ◽  
Electrophysiological Recordings

AbstractElectrophysiological recordings allow for monitoring the operation of proteins with high temporal resolution down to the single molecule level. This technique has been exploited to track either ion flow arising from channel opening or the synchronized movement of charged residues and/or ions within the membrane electric field. Here, we describe a novel type of current by using the serotonin transporter (SERT) as a model. We examined transient currents elicited on rapid application of specific SERT inhibitors. Our analysis shows that these currents originate from ligand binding and not from a conformational change. The Gouy-Chapman model predicts that a ligand-induced elimination/neutralization of surface charge must produce a displacement current and related apparent changes in membrane capacitance. Here we verified these predictions with SERT. Our observations demonstrate that ligand binding to a protein can be monitored in real time and in a label-free manner by recording the membrane capacitance.

The Application of Ionic Current Detection System for the Combustion Limit Control

1998 ◽  
Author(s):  
Yutaka Ohashi ◽  
Wataru Fukui ◽  
Fusako Tanabe ◽  
Atsushi Ueda
Keyword(s):  
Detection System ◽  
Ionic Current ◽  
Combustion Limit ◽  
Current Detection

scholarly journals A large size-selective DNA nanopore with sensing applications

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Rasmus P. Thomsen ◽  
Mette Galsgaard Malle ◽  
Anders Hauge Okholm ◽  
Swati Krishnan ◽  
Søren S.-R. Bohr ◽  
...  
Keyword(s):  
Lipid Bilayers ◽  
Single Molecule ◽  
Detection System ◽  
Optical Methods ◽  
Label Free ◽  
Sensing Applications ◽  
Large Size ◽  
Transmission Electron ◽  
Label Free Detection ◽  
External Signals

AbstractTransmembrane nanostructures like ion channels and transporters perform key biological functions by controlling flow of molecules across lipid bilayers. Much work has gone into engineering artificial nanopores and applications in selective gating of molecules, label-free detection/sensing of biomolecules and DNA sequencing have shown promise. Here, we use DNA origami to create a synthetic 9 nm wide DNA nanopore, controlled by programmable, lipidated flaps and equipped with a size-selective gating system for the translocation of macromolecules. Successful assembly and insertion of the nanopore into lipid bilayers are validated by transmission electron microscopy (TEM), while selective translocation of cargo and the pore mechanosensitivity are studied using optical methods, including single-molecule, total internal reflection fluorescence (TIRF) microscopy. Size-specific cargo translocation and oligonucleotide-triggered opening of the pore are demonstrated showing that the DNA nanopore can function as a real-time detection system for external signals, offering potential for a variety of highly parallelized sensing applications.

scholarly journals A label-free approach to detect ligand binding to cell surface proteins in real time

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Verena Burtscher ◽  
Matej Hotka ◽  
Yang Li ◽  
Michael Freissmuth ◽  
Walter Sandtner
Keyword(s):  
Ligand Binding ◽  
Real Time ◽  
Single Molecule ◽  
Membrane Capacitance ◽  
Surface Proteins ◽  
High Temporal Resolution ◽  
Label Free ◽  
Single Molecule Level ◽  
Electrophysiological Recordings ◽  
Displacement Currents

Electrophysiological recordings allow for monitoring the operation of proteins with high temporal resolution down to the single molecule level. This technique has been exploited to track either ion flow arising from channel opening or the synchronized movement of charged residues and/or ions within the membrane electric field. Here, we describe a novel type of current by using the serotonin transporter (SERT) as a model. We examined transient currents elicited on rapid application of specific SERT inhibitors. Our analysis shows that these currents originate from ligand binding and not from a long-range conformational change. The Gouy-Chapman model predicts that adsorption of charged ligands to surface proteins must produce displacement currents and related apparent changes in membrane capacitance. Here we verified these predictions with SERT. Our observations demonstrate that ligand binding to a protein can be monitored in real time and in a label-free manner by recording the membrane capacitance.

Label-free, mass-sensitive single-molecule imaging using interferometric scattering microscopy

2020 ◽  
Author(s):  
Nikolas Hundt
Keyword(s):  
Single Molecule ◽  
Cellular Systems ◽  
Single Molecule Imaging ◽  
Label Free ◽  
Measurement Sensitivity ◽  
Mass Distributions ◽  
Quantitative Measurements ◽  
Contrast Mechanism ◽  
Cellular Components ◽  
Scattering Signal

Abstract Single-molecule imaging has mostly been restricted to the use of fluorescence labelling as a contrast mechanism due to its superior ability to visualise molecules of interest on top of an overwhelming background of other molecules. Recently, interferometric scattering (iSCAT) microscopy has demonstrated the detection and imaging of single biomolecules based on light scattering without the need for fluorescent labels. Significant improvements in measurement sensitivity combined with a dependence of scattering signal on object size have led to the development of mass photometry, a technique that measures the mass of individual molecules and thereby determines mass distributions of biomolecule samples in solution. The experimental simplicity of mass photometry makes it a powerful tool to analyse biomolecular equilibria quantitatively with low sample consumption within minutes. When used for label-free imaging of reconstituted or cellular systems, the strict size-dependence of the iSCAT signal enables quantitative measurements of processes at size scales reaching from single-molecule observations during complex assembly up to mesoscopic dynamics of cellular components and extracellular protrusions. In this review, I would like to introduce the principles of this emerging imaging technology and discuss examples that show how mass-sensitive iSCAT can be used as a strong complement to other routine techniques in biochemistry.

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