1
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de Los Santos-Ramirez JM, Boyas-Chavez PG, Cerrillos-Ordoñez A, Mata-Gomez M, Gallo-Villanueva RC, Perez-Gonzalez VH. Trends and challenges in microfluidic methods for protein manipulation-A review. Electrophoresis 2024; 45:69-100. [PMID: 37259641 DOI: 10.1002/elps.202300056] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 05/06/2023] [Accepted: 05/11/2023] [Indexed: 06/02/2023]
Abstract
Proteins are important molecules involved in an immensely large number of biological processes. Being capable of manipulating proteins is critical for developing reliable and affordable techniques to analyze and/or detect them. Such techniques would enable the production of therapeutic agents for the treatment of diseases or other biotechnological applications (e.g., bioreactors or biocatalysis). Microfluidic technology represents a potential solution to protein manipulation challenges because of the diverse phenomena that can be exploited to achieve micro- and nanoparticle manipulation. In this review, we discuss recent contributions made in the field of protein manipulation in microfluidic systems using different physicochemical principles and techniques, some of which are miniaturized versions of already established macro-scale techniques.
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Affiliation(s)
| | - Pablo G Boyas-Chavez
- School of Engineering and Sciences, Tecnologico de Monterrey, Monterrey, Nuevo León, Mexico
| | | | - Marco Mata-Gomez
- School of Engineering and Sciences, Tecnologico de Monterrey, Monterrey, Nuevo León, Mexico
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2
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Matyushov DV. Nonlinear dielectric response of dilute protein solutions. RSC Adv 2023; 13:31123-31127. [PMID: 37881764 PMCID: PMC10594618 DOI: 10.1039/d3ra06033k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Accepted: 10/19/2023] [Indexed: 10/27/2023] Open
Abstract
A theory for the nonlinear dielectric response of dilute protein solutions is presented. The field-dependent dielectric function of the protein solution changes linearly with the electric field squared in the lowest order. The slope of this dependence is expressed in terms of the protein dipole moment M0, its volume fraction in solution η0, and the second osmotic virial coefficient. For practical conditions, the nonlinear dielectric response scales as η03M08. This strong dependence on the protein dipole moment and concentration establishes a sharp contrast between the nonlinear response of solvated proteins relative to the surrounding polar solvent. Nonlinear dielectric response can serve as a sensitive tool for monitoring protein conformations and physiological activity.
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Affiliation(s)
- Dmitry V Matyushov
- School of Molecular Sciences, Department of Physics, Arizona State University PO Box 871504 Tempe Arizona 85287-1504 USA
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3
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Elayan H, Eckford AW, Adve R. Selectivity of Protein Interactions Stimulated by Terahertz Signals. IEEE Trans Nanobioscience 2023; 22:318-328. [PMID: 35797314 DOI: 10.1109/tnb.2022.3189549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
It has been established that Terahertz (THz) band signals can interact with biomolecules through resonant modes. Specifically, of interest here, protein activation. Our research goal is to show how directing the mechanical signaling inside protein molecules using THz signals can control changes in their structure and activate associated biochemical and biomechanical events. To establish that, we formulate a selectivity metric that quantifies the system performance and captures the capability of the nanoantenna to induce a conformational change in the desired protein molecule/population. The metric provides a score between -1 and 1 that indicates the degree of control we have over the system to achieve targeted protein interactions. To develop the selectivity measure, we first use the Langevin stochastic equation driven by an external force to model the protein behavior. We then determine the probability of protein folding by computing the steady-state energy of the driven protein and then generalize our model to account for protein populations. Our numerical analysis results indicate that a maximum selectivity score is attained when only the targeted population experiences a folding behavior due to the impinging THz signal. From the achieved selectivity values, we conclude that the system response not only depends on the resonant frequency but also on the system controlling parameters namely, the nanoantenna force, the damping constant, and the abundance of each protein population. Based on the selectivity metric, the nanoantenna must be tuned to a frequency that is not necessarily the resonant frequency of the protein. The presented work sheds light on the potential associated with the electromagnetic-based control of protein networks, which could lead to a plethora of applications in the medical field ranging from bio-sensing to targeted therapy.
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4
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Riccardi M, Martin OJF. Electromagnetic Forces and Torques: From Dielectrophoresis to Optical Tweezers. Chem Rev 2023; 123:1680-1711. [PMID: 36719985 PMCID: PMC9951227 DOI: 10.1021/acs.chemrev.2c00576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Indexed: 02/02/2023]
Abstract
Electromagnetic forces and torques enable many key technologies, including optical tweezers or dielectrophoresis. Interestingly, both techniques rely on the same physical process: the interaction of an oscillating electric field with a particle of matter. This work provides a unified framework to understand this interaction both when considering fields oscillating at low frequencies─dielectrophoresis─and high frequencies─optical tweezers. We draw useful parallels between these two techniques, discuss the different and often unstated assumptions they are based upon, and illustrate key applications in the fields of physical and analytical chemistry, biosensing, and colloidal science.
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Affiliation(s)
- Marco Riccardi
- Nanophotonics and Metrology Laboratory, Swiss Federal Institute of Technology Lausanne (EPFL), EPFL-STI-NAM, Station 11, CH-1015Lausanne, Switzerland
| | - Olivier J. F. Martin
- Nanophotonics and Metrology Laboratory, Swiss Federal Institute of Technology Lausanne (EPFL), EPFL-STI-NAM, Station 11, CH-1015Lausanne, Switzerland
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5
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Prüfer M, Wenger C, Bier FF, Laux EM, Hölzel R. Activity of AC electrokinetically immobilized horseradish peroxidase. Electrophoresis 2022; 43:1920-1933. [PMID: 35904497 DOI: 10.1002/elps.202200073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 06/22/2022] [Accepted: 07/18/2022] [Indexed: 12/14/2022]
Abstract
Dielectrophoresis (DEP) is an AC electrokinetic effect mainly used to manipulate cells. Smaller particles, like virions, antibodies, enzymes, and even dye molecules can be immobilized by DEP as well. In principle, it was shown that enzymes are active after immobilization by DEP, but no quantification of the retained activity was reported so far. In this study, the activity of the enzyme horseradish peroxidase (HRP) is quantified after immobilization by DEP. For this, HRP is immobilized on regular arrays of titanium nitride ring electrodes of 500 nm diameter and 20 nm widths. The activity of HRP on the electrode chip is measured with a limit of detection of 60 fg HRP by observing the enzymatic turnover of Amplex Red and H2 O2 to fluorescent resorufin by fluorescence microscopy. The initial activity of the permanently immobilized HRP equals up to 45% of the activity that can be expected for an ideal monolayer of HRP molecules on all electrodes of the array. Localization of the immobilizate on the electrodes is accomplished by staining with the fluorescent product of the enzyme reaction. The high residual activity of enzymes after AC field induced immobilization shows the method's suitability for biosensing and research applications.
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Affiliation(s)
- Mareike Prüfer
- Fraunhofer Institute for Cell Therapy and Immunology, Branch Bioanalytics and Bioprocesses (IZI-BB), Potsdam-Golm, Germany
| | - Christian Wenger
- IHP GmbH - Leibniz Institute for Innovative Microelectronics, Frankfurt/Oder, Germany
| | - Frank F Bier
- Institute of Biochemistry and Biology, University of Potsdam, Potsdam-Golm, Germany
| | - Eva-Maria Laux
- Fraunhofer Institute for Cell Therapy and Immunology, Branch Bioanalytics and Bioprocesses (IZI-BB), Potsdam-Golm, Germany
| | - Ralph Hölzel
- Fraunhofer Institute for Cell Therapy and Immunology, Branch Bioanalytics and Bioprocesses (IZI-BB), Potsdam-Golm, Germany
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6
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Nasir NSA, Deivasigamani R, Wee MFMR, Hamzah AA, Zaid MHM, Rahim MKA, Kayani AA, Abdulhameed A, Buyong MR. Protein Albumin Manipulation and Electrical Quantification of Molecular Dielectrophoresis Responses for Biomedical Applications. MICROMACHINES 2022; 13:mi13081308. [PMID: 36014230 PMCID: PMC9415755 DOI: 10.3390/mi13081308] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 08/06/2022] [Accepted: 08/07/2022] [Indexed: 05/17/2023]
Abstract
Research relating to dielectrophoresis (DEP) has been progressing rapidly through time as it is a strong and controllable technique for manipulation, separation, preconcentration, and partitioning of protein. Extensive studies have been carried out on protein DEP, especially on Bovine Serum Albumin (BSA). However, these studies involve the usage of dye and fluorescent probes to observe DEP responses as the physical properties of protein albumin molecular structure are translucent. The use of dye and the fluorescent probe could later affect the protein's physiology. In this article, we review three methods of electrical quantification of DEP responses: electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and capacitance measurement for protein BSA DEP manipulation. The correlation of these methods with DEP responses is further discussed. Based on the observations on capacitance measurement, it can be deduced that the electrical quantifying method is reliable for identifying DEP responses. Further, the possibility of manipulating the protein and electrically quantifying DEP responses while retaining the original physiology of the protein and without the usage of dye or fluorescent probe is discussed.
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Affiliation(s)
- Nur Shahira Abdul Nasir
- Institute of Microengineering & Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia (UKM), Bangi 43600, Selangor, Malaysia
| | - Revathy Deivasigamani
- Institute of Microengineering & Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia (UKM), Bangi 43600, Selangor, Malaysia
| | - M. F. Mohd Razip Wee
- Institute of Microengineering & Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia (UKM), Bangi 43600, Selangor, Malaysia
| | - Azrul Azlan Hamzah
- Institute of Microengineering & Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia (UKM), Bangi 43600, Selangor, Malaysia
| | - Mohd Hazani Mat Zaid
- Institute of Microengineering & Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia (UKM), Bangi 43600, Selangor, Malaysia
| | | | - Aminuddin Ahmad Kayani
- Functional Materials and Microsystems Research Group and the Micro Nano Research Facility, School of Engineering, RMIT University, Melbourne, VIC 3001, Australia
| | - Abdullah Abdulhameed
- Department of Electronics & Communication Engineering, Faculty of Engineering & Petroleum, Hadhramout University, Al-Mukalla 50512, Hadhramout, Yemen
| | - Muhamad Ramdzan Buyong
- Institute of Microengineering & Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia (UKM), Bangi 43600, Selangor, Malaysia
- Correspondence: ; Tel.: +60-12-385-2713
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7
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Protein Dielectrophoresis: A Tale of Two Clausius–Mossottis or Something Else? MICROMACHINES 2022; 13:mi13020261. [PMID: 35208384 PMCID: PMC8876334 DOI: 10.3390/mi13020261] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 01/31/2022] [Accepted: 02/03/2022] [Indexed: 11/17/2022]
Abstract
Standard DEP theory, based on the Clausius–Mossotti (CM) factor derived from solving the boundary-value problem of macroscopic electrostatics, fails to describe the dielectrophoresis (DEP) data obtained for 22 different globular proteins over the past three decades. The calculated DEP force appears far too small to overcome the dispersive forces associated with Brownian motion. An empirical theory, employing the equivalent of a molecular version of the macroscopic CM-factor, predicts a protein’s DEP response from the magnitude of the dielectric β-dispersion produced by its relaxing permanent dipole moment. A new theory, supported by molecular dynamics simulations, replaces the macroscopic boundary-value problem with calculation of the cross-correlation between the protein and water dipoles of its hydration shell. The empirical and formal theory predicts a positive DEP response for protein molecules up to MHz frequencies, a result consistently reported by electrode-based (eDEP) experiments. However, insulator-based (iDEP) experiments have reported negative DEP responses. This could result from crystallization or aggregation of the proteins (for which standard DEP theory predicts negative DEP) or the dominating influences of electrothermal and other electrokinetic (some non-linear) forces now being considered in iDEP theory.
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8
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Dong X, Wan W, Zeng L, Jin W, Huang Y, Shen D, Bai Y, Zhao Q, Zhang L, Liu Y, Gao Z. Regulation of Fluorescence Solvatochromism To Resolve Cellular Polarity upon Protein Aggregation. Anal Chem 2021; 93:16447-16455. [PMID: 34859995 DOI: 10.1021/acs.analchem.1c03401] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Common solvatochromic fluorophores exhibit a bathochromic fluorescence emission wavelength shift accompanied by intensity attenuation due to the presence of nonradiative decay pathways at the excited state. Such intrinsic but inevitable fluorescence quenching of solvatochromism impedes its applications to faithfully quantify local polarity, especially in a polar environment. Herein, we report a new donor-π-acceptor (D-π-A) type solvatochromic fluorophore scaffold containing a perfluorophenyl group that exhibits both a solvatochromic emission wavelength shift and a controllable emission intensity upon polarity fluctuation. The regulation of fluorescence solvatochromism and colors was achieved by tuning the aryl donors. We exploited such desired solvatochromism of these probes to monitor protein misfolding and aggregation via wavelength shift. Finally, the polarity of pathogenic aggregated proteins was quantified by HaloTag bioorthogonal labeling technology in live cells. While much effort has been devoted to resolving the morphology of pathogenic aggregated proteins, this work provides quantitative hints regarding the chemical information at this disease-related protein interphase.
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Affiliation(s)
- Xuepeng Dong
- The Second Hospital of Dalian Medical University, 467 Zhongshan Road, Dalian, 116023, P. R. China
| | - Wang Wan
- CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, P. R. China
| | - Lianggang Zeng
- CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, P. R. China
| | - Wenhan Jin
- CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, P. R. China
| | - Yanan Huang
- CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, P. R. China
| | - Di Shen
- CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, P. R. China
| | - Yulong Bai
- CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, P. R. China.,University of the Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Qun Zhao
- CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, P. R. China
| | - Lihua Zhang
- CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, P. R. China
| | - Yu Liu
- CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, P. R. China
| | - Zhenming Gao
- The Second Hospital of Dalian Medical University, 467 Zhongshan Road, Dalian, 116023, P. R. China
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9
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Waskasi MM, Lazaric A, Heyden M. Solvent-mediated forces in protein dielectrophoresis. Electrophoresis 2021; 42:2060-2069. [PMID: 34302698 DOI: 10.1002/elps.202100087] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 07/09/2021] [Accepted: 07/15/2021] [Indexed: 12/23/2022]
Abstract
DEP is an established method to manipulate micrometer-sized particles, but standard continuum theories predict only negligible effects for nanometer-sized proteins despite contrary experimental evidence. A theoretical description of protein DEP needs to consider details on the molecular scale. Previous work toward this goal addressed the role of orientational polarization of static protein dipole moments for dielectrophoretic effects, which successfully predicts the general magnitude of dielectrophoretic forces on proteins but does not readily explain negative DEP forces observed for proteins in some experiments. However, contributions to the protein chemical potential due to protein-water interactions have not yet been considered in this context. Here, we utilize atomistic molecular dynamics simulations to evaluate polarization-induced changes in the protein solvation free energy, which result in a solvent-mediated contribution to dielectrophoretic forces. We quantify solvent-mediated dielectrophoretic forces for two proteins and a small peptide in water, which follow expectations for protein-water dipole-dipole interactions. The magnitude of solvent-mediated dielectrophoretic forces exceeds predictions of nonmolecular continuum theories, but plays a minor role for the total dielectrophoretic force for the simulated proteins due to dominant contributions from the orientational polarization of their static protein dipoles. However, we extrapolate that solvent-mediated contributions to negative protein DEP forces will become increasingly relevant for multidomain proteins, complexes and aggregates with large protein-water interfaces, as well as for high electric field frequencies, which provides a potential mechanism for corresponding experimental observations of negative protein DEP.
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Affiliation(s)
- Morteza M Waskasi
- School of Molecular Sciences, Arizona State University, Tempe, AZ, USA
| | | | - Matthias Heyden
- School of Molecular Sciences, Arizona State University, Tempe, AZ, USA
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10
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Perez‐Gonzalez VH. Particle trapping in electrically driven insulator-based microfluidics: Dielectrophoresis and induced-charge electrokinetics. Electrophoresis 2021; 42:2445-2464. [PMID: 34081787 PMCID: PMC9291494 DOI: 10.1002/elps.202100123] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 05/29/2021] [Accepted: 06/01/2021] [Indexed: 12/31/2022]
Abstract
Electrokinetically driven insulator‐based microfluidic devices represent an attractive option to manipulate particle suspensions. These devices can filtrate, concentrate, separate, or characterize micro and nanoparticles of interest. Two decades ago, inspired by electrode‐based dielectrophoresis, the concept of insulator‐based dielectrophoresis (iDEP) was born. In these microfluidic devices, insulating structures (i.e., posts, membranes, obstacles, or constrictions) built within the channel are used to deform the spatial distribution of an externally generated electric field. As a result, particles suspended in solution experience dielectrophoresis (DEP). Since then, it has been assumed that DEP is responsible for particle trapping in these devices, regardless of the type of voltage being applied to generate the electric field—direct current (DC) or alternating current. Recent findings challenge this assumption by demonstrating particle trapping and even particle flow reversal in devices that prevent DEP from occurring (i.e., unobstructed long straight channels stimulated with a DC voltage and featuring a uniform electric field). The theory introduced to explain those unexpected observations was then applied to conventional “DC‐iDEP” devices, demonstrating better prediction accuracy than that achieved with the conventional DEP‐centered theory. This contribution summarizes contributions made during the last two decades, comparing both theories to explain particle trapping and highlighting challenges to address in the near future.
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11
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Forouzanfar S, Pala N, Madou M, Wang C. Perspectives on C-MEMS and C-NEMS biotech applications. Biosens Bioelectron 2021; 180:113119. [PMID: 33711652 DOI: 10.1016/j.bios.2021.113119] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 02/19/2021] [Accepted: 02/25/2021] [Indexed: 02/04/2023]
Abstract
Carbon microelectromechanical system (C-MEMS) and carbon nanoelectromechanical system (C-NEMS) have been identified as promising technologies for a range of biotech applications, including electrochemical biosensors, biofuel cells, neural probes, and dielectrophoretic cell trapping. Research teams around the world have devoted more and more time to this field. After almost two decades of efforts on developing C-MEMS and C-NEMS, a review of the relevant progress and addressing future research opportunities and critical issues is in order. This review first introduces C-MEMS and C-NEMS fabrication processes that fall into two categories: photolithography- and non-photolithography- based techniques. Next, a detailed discussion of the state of the art, and technical challenges and opportunities associated with C-MEMS and C-NEMS devices used in biotech applications are presented. These devices are discussed in the relevant sub-sections of biosensors, biofuel cells, intracorporeal neural probe, dielectrophoresis cell trapping, and cell culture. The review concludes with an exposition of future perspectives in C-MEMS and C-NEMS.
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Affiliation(s)
- Shahrzad Forouzanfar
- Electrical and Computer Engineering, Florida International University, United States
| | - Nezih Pala
- Electrical and Computer Engineering, Florida International University, United States
| | - Marc Madou
- Mechanical and Aerospace Engineering, University of California Irvine, United States
| | - Chunlei Wang
- Mechanical and Materials Engineering, Florida International University, United States; Center for Study of Matter at Extreme Conditions, Florida International University, United States.
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12
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Affiliation(s)
- Matthias Heyden
- School of Molecular Sciences, Arizona State University, P.O. Box 871604, Tempe, Arizona 85287-1604, United States
| | - Dmitry V. Matyushov
- Department of Physics and School of Molecular Sciences, Arizona State University, P.O. Box 871504, Tempe, Arizona 85287-1504, United States
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13
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Hölzel R, Pethig R. Protein dielectrophoresis: Key dielectric parameters and evolving theory. Electrophoresis 2020; 42:513-538. [PMID: 33084076 DOI: 10.1002/elps.202000255] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 10/07/2020] [Accepted: 10/09/2020] [Indexed: 12/17/2022]
Abstract
Globular proteins exhibit dielectrophoresis (DEP) responses in experiments where the applied field gradient factor ∇E2 appears far too small, according to standard DEP theory, to overcome dispersive forces associated with the thermal energy kT of disorder. To address this a DEP force equation is proposed that replaces a previous empirical relationship between the macroscopic and microscopic forms of the Clausius-Mossotti factor. This equation relates the DEP response of a protein directly to the dielectric increment δε+ and decrement δε- that characterize its β-dispersion at radio frequencies, and also indirectly to its intrinsic dipole moment by way of providing a measure of the protein's effective volume. A parameter Γpw , taken as a measure of cross-correlated dipole interactions between the protein and its water molecules of hydration, is included in this equation. For 9 of the 12 proteins, for which an evaluation can presently be made, Γpw has a value of ≈4600 ± 120. These conclusions follow an analysis of the failure of macroscopic dielectric mixture (effective medium) theories to predict the dielectric properties of solvated proteins. The implication of a polarizability greatly exceeding the intrinsic value for a protein might reflect the formation of relaxor ferroelectric nanodomains in its hydration shell.
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Affiliation(s)
- Ralph Hölzel
- Fraunhofer Institute for Cell Therapy and Immunology, Branch Bioanalytics and Bioprocesses (IZI-BB), Potsdam-Golm, Germany
| | - Ronald Pethig
- Institute for Integrated Micro and Nanosystems, School of Engineering, University of Edinburgh, Edinburgh, UK
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14
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Chinappi M, Yamaji M, Kawano R, Cecconi F. Analytical Model for Particle Capture in Nanopores Elucidates Competition among Electrophoresis, Electroosmosis, and Dielectrophoresis. ACS NANO 2020; 14:15816-15828. [PMID: 33170650 PMCID: PMC8016366 DOI: 10.1021/acsnano.0c06981] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Accepted: 11/02/2020] [Indexed: 05/15/2023]
Abstract
The interaction between nanoparticles dispersed in a fluid and nanopores is governed by the interplay of hydrodynamical, electrical, and chemical effects. We developed a theory for particle capture in nanopores and derived analytical expressions for the capture rate under the concurrent action of electrical forces, fluid advection, and Brownian motion. Our approach naturally splits the average capture time in two terms, an approaching time due to the migration of particles from the bulk to the pore mouth and an entrance time associated with a free-energy barrier at the pore entrance. Within this theoretical framework, we described the standard experimental condition where a particle concentration is driven into the pore by an applied voltage, with specific focus on different capture mechanisms: under pure electrophoretic force, in the presence of a competition between electrophoresis and electroosmosis, and finally under dielectrophoretic reorientation of dipolar particles. Our theory predicts that dielectrophoresis is able to induce capture for both positive and negative voltages. We performed a dedicated experiment involving a biological nanopore (α-hemolysin) and a rigid dipolar dumbbell (realized with a β-hairpin peptide) that confirms the theoretically proposed capture mechanism.
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Affiliation(s)
- Mauro Chinappi
- Dipartimento
di Ingegneria Industriale, Università
di Roma Tor Vergata, Via del Politecnico 1, 00133 Rome, Italy
| | - Misa Yamaji
- Department
of Biotechnology and Life Science, Tokyo
University of Agriculture and Technology, Tokyo 184-8588, Japan
| | - Ryuji Kawano
- Department
of Biotechnology and Life Science, Tokyo
University of Agriculture and Technology, Tokyo 184-8588, Japan
| | - Fabio Cecconi
- CNR-Istituto
dei Sistemi Complessi, Via dei Taurini 19, I-00185 Rome, Italy
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15
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16
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Liu X, Zeng Q, Liu C, Wang L. A Fourier Transform-Induced Data Process for Label-Free Selective Nanopore Analysis under Sinusoidal Voltage Excitations. Anal Chem 2020; 92:11635-11643. [PMID: 32786474 DOI: 10.1021/acs.analchem.0c01339] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Nanopore analysis based on a resistive-pulse technique is an attractive tool for single-molecule detection in different fields, but it suffers a great drawback in selectivity. A common solution to this challenge is to add extra sensing aptamers and labels to analytes by improving the sensitivity of their pulses for distinguishing. Compared to the labeling methods, we alternatively develop and demonstrate a novel data process for label-free nanopore analysis that enables the conversion of resistive current signals to more specific frequency domain phase angle features with the contribution from both sinusoidal voltage excitation and Fourier transform. In particular, we find that the transmural capacitance induced by nanoparticle translocations under a sinusoidal voltage plays an important role in this process, making phase angle features more pronounced. In practical applications, the method is successfully applied to directly distinguish the translocation events through a nanopipette by their unique phase angles for similarly sized SiO2, Ag, and Au nanoparticles and soft living organisms of HeLa and LoVo and even in a more complicated case of a SiO2, Ag, and Au nanoparticle mixture.
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Affiliation(s)
- Xuye Liu
- School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, China
| | - Qiang Zeng
- School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, China
| | - Cheng Liu
- School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, China
| | - Lishi Wang
- School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, China
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17
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Abstract
The vibrational Stark effect in proteins yields line shifts indicative of strong internal electric fields up to a few volts per angstrom. These values are supported by numerical simulations of proteins. The simulations also show a significant breadth of field fluctuations translating to inhomogeneous broadening of vibrational lines. According to fluctuation-dissipation arguments, strong internal fields should lead to broad lines. Experimentally reported vibrational lines in proteins are, however, very narrow. This disconnect is explained here in terms of the insufficient (nonergodic) sampling of the protein's configurations on the lifetime of the vibrational probe. The slow component of the electric field fluctuations in proteins relaxes on the time scale of tens of nanoseconds and is dynamically frozen on the vibrational lifetime.
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Affiliation(s)
- Daniel R Martin
- Department of Physics, Arizona State University, P.O. Box 871504, Tempe, Arizona 85287, United States
| | - Dmitry V Matyushov
- Department of Physics and School of Molecular Sciences, Arizona State University, P.O. Box 871504, Tempe, Arizona 85287, United States
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Hölzel R, Pethig R. Protein Dielectrophoresis: I. Status of Experiments and an Empirical Theory. MICROMACHINES 2020; 11:E533. [PMID: 32456059 PMCID: PMC7281080 DOI: 10.3390/mi11050533] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/03/2020] [Revised: 05/20/2020] [Accepted: 05/20/2020] [Indexed: 12/04/2022]
Abstract
The dielectrophoresis (DEP) data reported in the literature since 1994 for 22 different globular proteins is examined in detail. Apart from three cases, all of the reported protein DEP experiments employed a gradient field factor ∇Em2 that is much smaller (in some instances by many orders of magnitude) than the ~4 1021 V2/m3 required, according to current DEP theory, to overcome the dispersive forces associated with Brownian motion. This failing results from the macroscopic Clausius-Mossotti (CM) factor being restricted to the range 1.0 > CM > -0.5. Current DEP theory precludes the protein's permanent dipole moment (rather than the induced moment) from contributing to the DEP force. Based on the magnitude of the β-dispersion exhibited by globular proteins in the frequency range 1 kHz-50 MHz, an empirically derived molecular version of CM is obtained. This factor varies greatly in magnitude from protein to protein (e.g., ~37,000 for carboxypeptidase; ~190 for phospholipase) and when incorporated into the basic expression for the DEP force brings most of the reported protein DEP above the minimum required to overcome dispersive Brownian thermal effects. We believe this empirically-derived finding validates the theories currently being advanced by Matyushov and co-workers.
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Affiliation(s)
- Ralph Hölzel
- Fraunhofer Institute for Cell Therapy and Immunology, Branch Bioanalytics and Bioprocesses (IZI-BB), Am Mühlenberg 13, 14476 Potsdam-Golm, Germany;
| | - Ronald Pethig
- School of Engineering, Institute for Integrated Micro and Nanosystems, University of Edinburgh, The King’s Buildings, Edinburgh EH9 3JF, UK
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Creation of an electrokinetic characterization library for the detection and identification of biological cells. Anal Bioanal Chem 2020; 412:3935-3945. [DOI: 10.1007/s00216-020-02621-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 03/19/2020] [Accepted: 03/26/2020] [Indexed: 11/26/2022]
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AC electrokinetic immobilization of organic dye molecules. Anal Bioanal Chem 2020; 412:3859-3870. [PMID: 32125465 PMCID: PMC7235070 DOI: 10.1007/s00216-020-02480-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 01/28/2020] [Accepted: 01/31/2020] [Indexed: 12/02/2022]
Abstract
The application of inhomogeneous AC electric fields for molecular immobilization is a very fast and simple method that does not require any adaptions to the molecule’s functional groups or charges. Here, the method is applied to a completely new category of molecules: small organic fluorescence dyes, whose dimensions amount to only 1 nm or even less. The presented setup and the electric field parameters used allow immobilization of dye molecules on the whole electrode surface as opposed to pure dielectrophoretic applications, where molecules are attracted only to regions of high electric field gradients, i.e., to the electrode tips and edges. In addition to dielectrophoresis and AC electrokinetic flow, molecular scale interactions and electrophoresis at short time scales are discussed as further mechanisms leading to migration and immobilization of the molecules. Graphical Abstract ![]()
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Matyushov DV. Electrostatic solvation and mobility in uniform and non-uniform electric fields: From simple ions to proteins. BIOMICROFLUIDICS 2019; 13:064106. [PMID: 31737155 PMCID: PMC6837943 DOI: 10.1063/1.5124390] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Accepted: 10/23/2019] [Indexed: 06/10/2023]
Abstract
A number of observations related to interfacial electrostatics of polar liquids question the traditional assumption of dielectric theories that bulk dielectric properties can be continuously extended to the dividing surface separating the solute from the solvent. The deficiency of this approximation can be remedied by introducing local interface susceptibilities and the interface dielectric constant. Asymmetries of ionic hydration thermodynamics and of the mobility between cations and anions can be related to different propensities of the water molecules to orient their dipole toward and outward from solutes of opposite charges. This electrostatic asymmetry is reflected in different interface dielectric constants for cations and anions. The interface of water with neutral solutes is spontaneously polarized due to preferential water orientations in the interface. This phenomenon is responsible for a nonzero cavity potential directly related to a nonzero surface charge. This connection predicts that particles allowing a nonzero cavity potential must show mobility in an external electric field even if the net charge of the particle is zero. The theory predicts that a positive cavity potential and a positive surface charge translate to an effectively negative solute charge reported by mobility measurements. Passing of the cavity potential through a minimum found in simulations might be the origin of the maximum of mobility vs the ionic size observed experimentally. Finally, mobility of proteins in the field gradient (dielectrophoresis) is many orders of magnitude greater than predicted by the traditionally used Clausius-Mossotti equation. Two reasons contribute to this disagreement: (i) a failure of Maxwell's electrostatics to describe the cavity-field susceptibility and (ii) the neglect of the protein permanent dipole by the Clausius-Mossotti equation. An analytical relation between the dielectrophoretic susceptibility and dielectric spectroscopy of solutions provides direct access to this parameter, confirming the failure of the Clausius-Mossotti equation in application to protein dielectrophresis.
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Affiliation(s)
- Dmitry V Matyushov
- Department of Physics and School of Molecular Sciences, Arizona State University, PO Box 871504, Tempe, Arizona 85287-1504, USA
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22
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Pethig R. Limitations of the Clausius-Mossotti function used in dielectrophoresis and electrical impedance studies of biomacromolecules. Electrophoresis 2019; 40:2575-2583. [PMID: 30861572 DOI: 10.1002/elps.201900057] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 02/26/2019] [Accepted: 02/26/2019] [Indexed: 01/08/2023]
Abstract
Dielectrophoresis (DEP) studies have progressed from the microscopic scale of cells and bacteria, through the mesoscale of virions to the molecular scale of DNA and proteins. The Clausius-Mossotti function, based on macroscopic electrostatics, is invariably employed in the analyses of all these studies. The limitations of this practice are explored, with the conclusion that it should be abandoned for the DEP study of proteins and modified for native DNA. For macromolecular samples in general, a DEP theory that incorporates molecular-scale interactions and the influence of permanent dipoles is more appropriate. Experimental ways to test these conclusions are proposed.
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Affiliation(s)
- Ronald Pethig
- School of Engineering, Institute for Integrated Micro and Nanosystems, University of Edinburgh, Edinburgh, UK
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24
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Affiliation(s)
- Daihyun Kim
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
- Center for Applied Structural Discovery, The Biodesign Institute, Arizona State University, Tempe, Arizona 85287, United States
| | - Mukul Sonker
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
- Center for Applied Structural Discovery, The Biodesign Institute, Arizona State University, Tempe, Arizona 85287, United States
| | - Alexandra Ros
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, United States
- Center for Applied Structural Discovery, The Biodesign Institute, Arizona State University, Tempe, Arizona 85287, United States
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