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Zhang L, Wahab OJ, Jallow AA, O’Dell ZJ, Pungsrisai T, Sridhar S, Vernon KL, Willets KA, Baker LA. Recent Developments in Single-Entity Electrochemistry. Anal Chem 2024; 96:8036-8055. [PMID: 38727715 PMCID: PMC11112546 DOI: 10.1021/acs.analchem.4c01406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Affiliation(s)
- L. Zhang
- Department
of Chemistry, Texas A&M University, College Station, Texas 77845, United States
| | - O. J. Wahab
- Department
of Chemistry, Texas A&M University, College Station, Texas 77845, United States
| | - A. A. Jallow
- Department
of Chemistry, Texas A&M University, College Station, Texas 77845, United States
| | - Z. J. O’Dell
- Department
of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - T. Pungsrisai
- Department
of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - S. Sridhar
- Department
of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - K. L. Vernon
- Department
of Chemistry, Texas A&M University, College Station, Texas 77845, United States
| | - K. A. Willets
- Department
of Chemistry, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - L. A. Baker
- Department
of Chemistry, Texas A&M University, College Station, Texas 77845, United States
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Hussein EA, Rice B, White RJ. Tuning the Probe-Bilayer Architecture of Silver Nanoneedle-based Ion Channel Probes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:7234-7241. [PMID: 38498453 DOI: 10.1021/acs.langmuir.4c00454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/20/2024]
Abstract
Ion channel probes, as one of the ion channel platforms, provide an appealing opportunity to perform localized detection with a high precision level. These probes come basically in two classes: glass and metal. While the glass-based probes showed the potential to be employed for molecular sensing and chemical imaging, these probes still suffer from limited resolution and lack of control over protein insertion. On the other hand, metal-based nanoneedle probes (gold and silver) have been recently developed to allow reducing probe dimensions to the nanoscale geometry. More specifically, silver probes are preferable owing to their ability to mitigate the channel current decay observed with gold probes and provide a stable DC channel current. However, there are still some challenges related to the probe design and bilayer curvature that render such probes insensitive to small changes in the tip-substrate distance. Herein, we introduce two main pathways to control the probe-bilayer architecture; the first is by altering the probe shape and geometry during the fabrication process of silver probes. The second pathway is by altering the surface characteristics of the silver probe via an electrophoretic deposition process. Our findings reveal that varying the electrochemical etching parameters results in different probe geometries and producing sharper tips with a 2-fold diameter reduction. In addition, the electrophoretic deposition of a cathodic paint on the silver nanoneedle surface led to a miniaturized exposed silver tip that enables the formation of a confined bilayer. We further investigated the characteristics of bilayers supported on both the sharper nanoneedles and the HSR-coated silver probes produced by controlling the etching conditions and electrodeposition process, respectively. We believe this work paves the way to rationally design silver nanoneedle ion channel probes, which are well suited for localized molecular sensing and chemical imaging.
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Affiliation(s)
- Essraa A Hussein
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221, United States
| | - Brittany Rice
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221, United States
| | - Ryan J White
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221, United States
- Department of Electrical Engineering and Computer Science, University of Cincinnati, Cincinnati, Ohio 45221, United States
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Wei X, Ma D, Ou J, Song G, Guo J, Robertson JW, Wang Y, Wang Q, Liu C. Narrowing Signal Distribution by Adamantane Derivatization for Amino Acid Identification Using an α-Hemolysin Nanopore. NANO LETTERS 2024; 24:1494-1501. [PMID: 38264980 PMCID: PMC10947511 DOI: 10.1021/acs.nanolett.3c03593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2024]
Abstract
The rapid progress in nanopore sensing has sparked interest in protein sequencing. Despite recent notable advancements in amino acid recognition using nanopores, chemical modifications usually employed in this process still need further refinements. One of the challenges is to enhance the chemical specificity to avoid downstream misidentification of amino acids. By employing adamantane to label proteinogenic amino acids, we developed an approach to fingerprint individual amino acids using the wild-type α-hemolysin nanopore. The unique structure of adamantane-labeled amino acids (ALAAs) improved the spatial resolution, resulting in distinctive current signals. Various nanopore parameters were explored using a machine-learning algorithm and achieved a validation accuracy of 81.3% for distinguishing nine selected amino acids. Our results not only advance the effort in single-molecule protein characterization using nanopores but also offer a potential platform for studying intrinsic and variant structures of individual molecules.
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Affiliation(s)
- Xiaojun Wei
- Department of Biomedical Engineering, University of South Carolina, Columbia, SC 29208, United States
- Department of Chemical Engineering, University of South Carolina, Columbia, SC 29208, United States
| | - Dumei Ma
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208, United States
| | - Junlin Ou
- Department of Mechanical Engineering, University of South Carolina, Columbia, SC 29208, United States
| | - Ge Song
- Department of Mechanical Engineering, University of South Carolina, Columbia, SC 29208, United States
| | - Jiawei Guo
- Department of Mechanical Engineering, University of South Carolina, Columbia, SC 29208, United States
| | - Joseph W.F. Robertson
- Biophysics and Biomedical Measurement Group, Microsystems and Nanotechnology Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, United States
| | - Yi Wang
- Department of Mechanical Engineering, University of South Carolina, Columbia, SC 29208, United States
| | - Qian Wang
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208, United States
| | - Chang Liu
- Department of Biomedical Engineering, University of South Carolina, Columbia, SC 29208, United States
- Department of Chemical Engineering, University of South Carolina, Columbia, SC 29208, United States
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Hussein EA, White RJ. Maintaining Single-Channel Recordings on a Silver Nanoneedle through Probe Design and Feedback Tip Positioning Control. J Phys Chem B 2022; 126:10111-10119. [PMID: 36395597 DOI: 10.1021/acs.jpcb.2c06275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Ion channel proteins showed great promise in the field of nanopore sensing and molecular flux imaging applications due to the atomic-level precision of the pore size and a high signal-to-noise ratio. More specifically, ion channel probes, where the protein channels are integrated at the end of a solid probe, can achieve highly localized detection. Metal probe materials such as gold and silver have been developed to support lipid bilayers and enable the use of smaller probes, or nanoneedles, compared to more traditional glass micropipette ion channel probes. Silver probes are preferable because they support sustained DC stable channel current due to the AgCl layer formed around the tip during the fabrication process. However, one of the current challenges in ion channel measurements is maintaining a single-channel recording. Multiple protein insertions complicate data analysis and destabilize the bilayer. Herein, we combine the promising probe material (Ag/AgCl) with an approach based on current feedback-controlled tip positioning to maintain long-term single-channel recordings for up to 3 h. We develop a hybrid positioning control system, where the channel current is used as feedback to control the vertical movement of the silver tip and, subsequently, control the number of protein channels inserted in the lipid membrane. Our findings reveal that the area of the lipid bilayer decreases with moving the silver tip up (i.e., decreasing the displacement in the z-direction). By reducing the bilayer area around the fine silver tip, we minimize the probability of multiple insertions and remove unwanted proteins. In addition, we characterize the effect of lipid properties such as fluidity on the lipid membrane area. We believe that the use of silver nanoneedles, which enables DC stable channel current, coupled with the developed tip displacement mechanism will offer more opportunities to employ these probes for chemical imaging and mapping different surfaces.
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Affiliation(s)
- Essraa A Hussein
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio45221, United States
| | - Ryan J White
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio45221, United States.,Department of Electrical Engineering and Computer Science, University of Cincinnati, Cincinnati, Ohio45221, United States
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Hussein EA, Rice B, White RJ. Recent advances in ion-channel probes for nanopore sensing: Insights into the probe architectures. Anal Chim Acta 2022; 1224:340162. [DOI: 10.1016/j.aca.2022.340162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 07/05/2022] [Accepted: 07/08/2022] [Indexed: 11/01/2022]
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