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Surface morphology live-cell imaging reveals how macropinocytosis inhibitors affect membrane dynamics. Electrochim Acta 2022. [DOI: 10.1016/j.electacta.2022.141783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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Abstract
Scanning ion conductance microscopy (SICM) has emerged as a versatile tool for studies of interfaces in biology and materials science with notable utility in biophysical and electrochemical measurements. The heart of the SICM is a nanometer-scale electrolyte filled glass pipette that serves as a scanning probe. In the initial conception, manipulations of ion currents through the tip of the pipette and appropriate positioning hardware provided a route to recording micro- and nanoscopic mapping of the topography of surfaces. Subsequent advances in instrumentation, probe design, and methods significantly increased opportunities for SICM beyond recording topography. Hybridization of SICM with coincident characterization techniques such as optical microscopy and faradaic electrodes have brought SICM to the forefront as a tool for nanoscale chemical measurement for a wide range of applications. Modern approaches to SICM realize an important tool in analytical, bioanalytical, biophysical, and materials measurements, where significant opportunities remain for further exploration. In this review, we chronicle the development of SICM from the perspective of both the development of instrumentation and methods and the breadth of measurements performed.
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Affiliation(s)
- Cheng Zhu
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Kaixiang Huang
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Natasha P Siepser
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Lane A Baker
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, Indiana 47405, United States
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Choi MH, Jeong S, Wang Y, Cho SJ, Park SI, Ye X, Baker LA. Characterization of Ligand Adsorption at Individual Gold Nanocubes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:7701-7711. [PMID: 34143943 DOI: 10.1021/acs.langmuir.1c00694] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Cetyltrimethylammonium bromide (CTAB) is a widely used surfactant that aids the aqueous synthesis of colloidal nanoparticles. However, the presence of residual CTAB on nanoparticle surfaces can significantly impact nanoparticle applications, such as catalysis and sensing, under hydrated conditions. As such, consideration of the presence and quantity of CTAB on nanoparticle surfaces under hydrated conditions is of significance. Herein, as part of an integrated material characterization framework, we demonstrate the feasibility of in situ atomic force microscopy (AFM) to detect CTAB on the surface of Au nanocubes (Au NCs) under hydrated conditions, which enabled superior characterization compared to conventional spectroscopic methods. In situ force-distance (FD) spectroscopy and Kelvin probe force microscopy (KPFM) measurements support additional characterization of adsorbed CTAB, while correlative in situ AFM and scanning electron microscopy (SEM) measurements were used to evaluate sequential steps of CTAB removal from Au NCs across hydrated and dehydrated environments, respectively. Notably, a substantial quantity of CTAB remained on the Au NC surface after methanol washing, which was detected in AFM measurements but was not detected in infrared spectroscopy measurements. Subsequent electrochemical cleaning was found to be critically important to remove CTAB from the Au NC surface. Correlative measurements were also performed on individual nanoparticles, which further validate the method described here as a powerful tool to determine the extent and degree of CTAB removal from nanoparticle surfaces. This AFM-based method is broadly applicable to characterize the presence and removal of ligands from nanomaterial surfaces under hydrated conditions.
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Affiliation(s)
- Myung-Hoon Choi
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Soojin Jeong
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Yi Wang
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Sang-Joon Cho
- Park Systems Corporation, KANC 4F, Gwanggyo-ro 109, Suwon 16229, Korea
| | - Sang-Il Park
- Park Systems Corporation, KANC 4F, Gwanggyo-ro 109, Suwon 16229, Korea
| | - Xingchen Ye
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - Lane A Baker
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, Indiana 47405, United States
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Alden SE, Siepser NP, Patterson JA, Jagdale GS, Choi M, Baker LA. Array Microcell Method (AMCM) for Serial Electroanalysis. ChemElectroChem 2020; 7:1084-1091. [PMID: 36588586 PMCID: PMC9798888 DOI: 10.1002/celc.201901976] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
We describe a method for electrochemical measurement and synthesis based on the combination of a mobile micropipette and a microelectrode array, which we term the array microcell method (AMCM). AMCM has the ability to address single electrodes within a microelectrode array (MEA) and provides a simple, low-cost format to enable versatile electrochemical measurements. In AMCM, a droplet at the tip of a movable micropipette (inner diameter of 50 μm) functions as an electrochemical cell, in which the electrode area is defined by a microelectrode of the array. We also report carbon MEAs that are well suited for AMCM and are fabricated from pyrolyzed photoresist films (PPFs). PPF-MEAs with nominal electrode diameters of 5.5 μm are characterized by AMCM, standard macroscale electrochemical methods, and finite element modeling. The versatility of AMCM is demonstrated by measurement of single Pt microparticles and by electrodeposition of shapecontrolled Pt nanoparticles.
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Affiliation(s)
- Sasha E Alden
- Department of Chemistry, Indiana University, 800 E Kirkwood, Bloomington, 47405, Indiana (USA)
| | - Natasha P Siepser
- Department of Chemistry, Indiana University, 800 E Kirkwood, Bloomington, 47405, Indiana (USA)
| | - Jacqueline A Patterson
- Department of Chemistry, Indiana University, 800 E Kirkwood, Bloomington, 47405, Indiana (USA)
| | - Gargi S Jagdale
- Department of Chemistry, Indiana University, 800 E Kirkwood, Bloomington, 47405, Indiana (USA)
| | - Myunghoon Choi
- Department of Chemistry, Indiana University, 800 E Kirkwood, Bloomington, 47405, Indiana (USA)
| | - Lane A Baker
- Department of Chemistry, Indiana University, 800 E Kirkwood, Bloomington, 47405, Indiana (USA)
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Rabinowitz J, Edwards MA, Whittier E, Jayant K, Shepard KL. Nanoscale Fluid Vortices and Nonlinear Electroosmotic Flow Drive Ion Current Rectification in the Presence of Concentration Gradients. J Phys Chem A 2019; 123:8285-8293. [PMID: 31264868 PMCID: PMC6911310 DOI: 10.1021/acs.jpca.9b04075] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Ion current rectification (ICR) is a transport phenomenon in which an electrolyte conducts unequal currents at equal and opposite voltages. Here, we show that nanoscale fluid vortices and nonlinear electroosmotic flow (EOF) drive ICR in the presence of concentration gradients. The same EOF can yield negative differential resistance (NDR), in which current decreases with increasing voltage. A finite element model quantitatively reproduces experimental ICR and NDR recorded across glass nanopipettes under concentration gradients. The model demonstrates that spatial variations of electrical double layer properties induce the nanoscale vortices and nonlinear EOF. Experiments are performed in conditions directly related to scanning probe imaging and show that quantitative understanding of nanoscale transport under concentration gradients requires accounting for EOF. This characterization of nanopipette transport physics will benefit diverse experimentation, pushing the resolution limits of chemical and biophysical recordings.
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Affiliation(s)
| | - Martin A Edwards
- Department of Chemistry , University of Utah , Salt Lake City , Utah 84112 , United States
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Venkatesh V, Heinemann C, Sundaresan VB. Surface-tracked scanning ion conductance microscopy: A novel imaging technique for measuring topography-correlated transmembrane ion transport through porous substrates. Micron 2019; 120:57-65. [PMID: 30776683 DOI: 10.1016/j.micron.2019.01.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 01/25/2019] [Accepted: 01/30/2019] [Indexed: 01/09/2023]
Abstract
Ion transport through porous substrates is ubiquitous in biological and synthetic materials, and fundamental for chemical separation, drug delivery and bio-sensing. Contemporary imaging techniques for simultaneously characterizing topography and ion transport through porous substrates are limited in range and resolution. In this paper, we demonstrate 'surface-tracked scanning ion conductance microscopy' as a technique to image topography of a porous substrate and simultaneously measure voltage-driven transmembrane ion transport. This technique uses the principles of 'shear-force tracking' to image the surface of a polycarbonate track-etch membrane, and chronoamperometry to reconstruct topography-correlated transmembrane ion transport through the membrane at different transmembrane potentials. Spatial transmembrane transport through individual pores is modeled using Goldman-Hodgkin-Katz (GHK) theory to examine the effects of shear-force modulation on magnitude of transmembrane currents recorded with a nanopipette. The modeled transmembrane current through the porous membrane is compared with experimental behavior, and discrepancies between predicted values and measured data are outlined. The proposed surface-tracked imaging mode allows for rapid assessment (approximately 7 s/μm2) of interfacial processes at the nanoscale and addresses a bottleneck for stable, large-area characterization of porous substrates using scanning ion conductance microscopy.
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Affiliation(s)
- Vijay Venkatesh
- Department of Mechanical and Aerospace Engineering, The Ohio State University, 201 W 19th Ave, Columbus, OH 43210, United States
| | - Christian Heinemann
- HEKA Elektronik Dr. Schulze GmbH, Wiesenstraße 71, Lambrecht, Pfalz, Germany
| | - Vishnu Baba Sundaresan
- Department of Mechanical and Aerospace Engineering, The Ohio State University, 201 W 19th Ave, Columbus, OH 43210, United States.
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Bentley CL, Edmondson J, Meloni GN, Perry D, Shkirskiy V, Unwin PR. Nanoscale Electrochemical Mapping. Anal Chem 2018; 91:84-108. [PMID: 30500157 DOI: 10.1021/acs.analchem.8b05235] [Citation(s) in RCA: 94] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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