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Wang Z, Yu H, Liyanage A, Qiu J, Thushara D, Bao B, Zhao S. Collective diffusion of charged nanoparticles in microchannel under electric field. Chem Eng Sci 2022. [DOI: 10.1016/j.ces.2021.117264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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2
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Ly KL, Hu P, Pham LHP, Luo X. Flow-assembled chitosan membranes in microfluidics: recent advances and applications. J Mater Chem B 2021; 9:3258-3283. [PMID: 33725061 PMCID: PMC8369861 DOI: 10.1039/d1tb00045d] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The integration of membranes in microfluidic devices has been extensively exploited for various chemical engineering and bioengineering applications over the past few decades. To augment the applicability of membrane-integrated microfluidic platforms for biomedical and tissue engineering studies, a biologically friendly fabrication process with naturally occurring materials is highly desired. The in situ preparation of membranes involving interfacial reactions between parallel laminar flows in microfluidic networks, known as the flow-assembly technique, is one of the most biocompatible approaches. Membranes of many types with flexible geometries have been successfully assembled inside complex microchannels using this facile and versatile flow-assembly approach. Chitosan is a naturally abundant polysaccharide known for its pronounced biocompatibility, biodegradability, good mechanical stability, ease of modification and processing, and film-forming ability under near-physiological conditions. Chitosan membranes assembled by flows in microfluidics are freestanding, robust, semipermeable, and well-aligned in microstructure, and show high affinity to bioactive reagents and biological components (e.g. biomolecules, nanoparticles, or cells) that provide facile biological functionalization of microdevices. Here, we discuss the recent developments and optimizations in the flow-assembly of chitosan membranes and chitosan-based membranes in microfluidics. Furthermore, we recapitulate the applications of the chitosan membrane-integrated microfluidic platforms dedicated to biology, biochemistry, and drug release fields, and envision the future developments of this important platform with versatile functions.
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Affiliation(s)
- Khanh L Ly
- Department of Biomedical Engineering, The Catholic University of America, Washington, DC 20064, USA
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3
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Yen WK, Hsu JP. Electrokinetic behavior of a pH-regulated dielectric cylindrical nanopore. J Colloid Interface Sci 2021; 588:94-100. [PMID: 33388590 DOI: 10.1016/j.jcis.2020.12.050] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 12/15/2020] [Accepted: 12/16/2020] [Indexed: 10/22/2022]
Abstract
A continuum model is adopted to describe the electrokinetic behavior of a pH-regulated cylindrical nanopore, the surface of which has charge-regulated carboxyl groups. We focus on the influences of the permittivity of the nanopore material, nanopore size, salt concentration, and solution pH on this behavior, and the underlying mechanisms. The influence of the nanopore permittivity becomes significant when a nanopore is shorter than ca. 50 nm. It is interesting to observe that if it is longer than ca. 100 nm, the nanopore conductance decreases with increasing permittivity. If it is sufficiently short, the conductance increases with increasing permittivity. If the nanopore length takes a medium level, the conductance is insensitive to the variation in the permittivity. For a short nanopore (~20 nm), the conductivity increases with increasing permittivity. However, if pH is sufficiently high, it becomes insensitive to permittivity. Although the larger the permittivity the greater the conductivity, in general, this effect becomes insignificant when the bulk salt concentration is sufficiently high, implying that the effect of membrane polarization is important only if the bulk salt concentration is sufficiently low.
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Affiliation(s)
- Wei-Kuan Yen
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan
| | - Jyh-Ping Hsu
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan; Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan.
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4
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Alizadeh A, Hsu WL, Wang M, Daiguji H. Electroosmotic flow: From microfluidics to nanofluidics. Electrophoresis 2021; 42:834-868. [PMID: 33382088 PMCID: PMC8247933 DOI: 10.1002/elps.202000313] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Revised: 12/16/2020] [Accepted: 12/19/2020] [Indexed: 01/06/2023]
Abstract
Electroosmotic flow (EOF), a consequence of an imposed electric field onto an electrolyte solution in the tangential direction of a charged surface, has emerged as an important phenomenon in electrokinetic transport at the micro/nanoscale. Because of their ability to efficiently pump liquids in miniaturized systems without incorporating any mechanical parts, electroosmotic methods for fluid pumping have been adopted in versatile applications—from biotechnology to environmental science. To understand the electrokinetic pumping mechanism, it is crucial to identify the role of an ionically polarized layer, the so‐called electrical double layer (EDL), which forms in the vicinity of a charged solid–liquid interface, as well as the characteristic length scale of the conducting media. Therefore, in this tutorial review, we summarize the development of electrical double layer models from a historical point of view to elucidate the interplay and configuration of water molecules and ions in the vicinity of a solid–liquid interface. Moreover, we discuss the physicochemical phenomena owing to the interaction of electrical double layer when the characteristic length of the conducting media is decreased from the microscale to the nanoscale. Finally, we highlight the pioneering studies and the most recent works on electro osmotic flow devoted to both theoretical and experimental aspects.
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Affiliation(s)
- Amer Alizadeh
- Department of Mechanical Engineering, The University of Tokyo, Tokyo, Japan
| | - Wei-Lun Hsu
- Department of Mechanical Engineering, The University of Tokyo, Tokyo, Japan
| | - Moran Wang
- Department of Engineering Mechanics, Tsinghua University, Beijing, P. R. China
| | - Hirofumi Daiguji
- Department of Mechanical Engineering, The University of Tokyo, Tokyo, Japan
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5
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Wang Z, Hsu WL, Tsuchiya S, Paul S, Alizadeh A, Daiguji H. Joule Heating Effects on Transport-Induced-Charge Phenomena in an Ultrathin Nanopore. MICROMACHINES 2020; 11:E1041. [PMID: 33256113 PMCID: PMC7761093 DOI: 10.3390/mi11121041] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/07/2020] [Revised: 11/21/2020] [Accepted: 11/24/2020] [Indexed: 01/14/2023]
Abstract
Transport-induced-charge (TIC) phenomena, in which the concentration imbalance between cations and anions occurs when more than two chemical potential gradients coexist within an ultrathin dimension, entail numerous nanofluidic systems. Evidence has indicated that the presence of TIC produces a nonlinear response of electroosmotic flow to the applied voltage, resulting in complex fluid behavior. In this study, we theoretically investigate thermal effects due to Joule heating on TIC phenomena in an ultrathin nanopore by computational fluid dynamics simulation. Our modeling results show that the rise of local temperature inside the nanopore significantly enhances TIC effects and thus has a significant influence on electroosmotic behavior. A local maximum of the solution conductivity occurs near the entrance of the nanopore at the high salt concentration end, resulting in a reversal of TIC across the nanopore. The Joule heating effects increase the reversal of TIC with the synergy of the negatively charged nanopore, and they also enhance the electroosmotic flow regardless of whether the nanopore is charged. These theoretical observations will improve our knowledge of nonclassical electrokinetic phenomena for flow control in nanopore systems.
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Affiliation(s)
| | - Wei-Lun Hsu
- Department of Mechanical Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan; (Z.W.); (S.T.); (S.P.); (A.A.)
| | | | | | | | - Hirofumi Daiguji
- Department of Mechanical Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan; (Z.W.); (S.T.); (S.P.); (A.A.)
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6
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Ly KL, Raub CB, Luo X. Tuning the porosity of biofabricated chitosan membranes in microfluidics with co-assembled nanoparticles as templates. MATERIALS ADVANCES 2020; 1:34-44. [PMID: 33073238 PMCID: PMC7518516 DOI: 10.1039/d0ma00073f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 03/05/2020] [Indexed: 05/04/2023]
Abstract
Biopolymer membranes assembled in microfluidic devices offer many biological process- and analysis-related applications. One of the key characteristics of bio-fabricated membranes is their porosity, which regulates the transport of molecules, ions, or particles and contributes to their semi-permeability and selectivity. This study aims to tune the porosity of biofabricated chitosan membranes (CM) using incorporated nanoparticles as templates. CM with polystyrene nanoparticles (CM-np) were assembled by flow in microchannel networks. The membranes with incorporated nanoparticles were crosslinked with glutaraldehyde, and then the nanoparticles were dissolved with dimethyl sulfoxide. The in situ synthesized porous CM (pCM) were characterized with scanning electron microscopy and polarized light microscopy. Permeability tests confirmed the increased pore sizes of the pCM and enhanced permeability to macromolecules. Sharper static gradients in three-channel microfluidic devices were demonstrated with the pCM as compared to those with the original CM. The capability to customize the porosity of flow-assembled, freestanding and robust biopolymer membranes inside a microfluidic network is attractive and broadens the applications of these membranes in biomolecular and cellular studies.
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Affiliation(s)
- Khanh L Ly
- Department of Biomedical Engineering , Catholic University of America , Washington , DC 20064 , USA
| | - Christopher B Raub
- Department of Biomedical Engineering , Catholic University of America , Washington , DC 20064 , USA
| | - Xiaolong Luo
- Department of Mechanical Engineering , Catholic University of America , Washington , DC 20064 , USA .
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7
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Nanochannel Gradient Separations. Methods Mol Biol 2018. [PMID: 30488390 DOI: 10.1007/978-1-4939-8964-5_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Gradient-based electrophoretic separations enable simultaneous separation and concentration of molecules. Compared with conventional injection-based separations, they enable enrichment of low-concentration analytes from larger sample volumes that are not limited by an injection volume. We have demonstrated that a nanochannel, connecting two chemically different reservoirs, can maintain a stationary chemical gradient while trapping biomolecules and effectively averaging out many of the complex physicochemical hydrodynamics that would broaden the bands in a meso- or microscale capillary. Here we describe chemical and physical methods that enable this work.
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Hsu WL, Hwang J, Daiguji H. Theory of Transport-Induced-Charge Electroosmotic Pumping toward Alternating Current Resistive Pulse Sensing. ACS Sens 2018; 3:2320-2326. [PMID: 30350951 DOI: 10.1021/acssensors.8b00635] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
In this work, we study transport-induced-charge electroosmosis toward alternating current resistive pulse sensing for the next generation of biomedical applications. Transport-induced-charge electroosmosis, being a new class of electrokinetic phenomenon, occurs as a salt concentration gradient works in synergy with an electric field in ultrathin nanopores. Apart from the conventional electric double layer-governed electroosmotic flow in which the flow behavior is subject to the surface charge, it is found that the transport-induced-charge electroosmotic flow behaves independently of surface charge magnitude but can be linearly regulated by the bulk salt concentration bias. The reversal of the electric field simultaneously inverses the induced charge allowing the establishment of a unidirectional flow under the application of a periodic alternating current field. This unique phenomenon permits continuous water and nanoparticles pumping through a two-dimensional material nanopore in spite of the reversal of the electric field. Built upon this mechanism, we propose a theoretical prototype of alternating current resistive pulse sensing in a two-dimensional nanopore system.
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Affiliation(s)
- Wei-Lun Hsu
- Department of Mechanical Engineering, The University of Tokyo, Tokyo 113-8656, Japan
| | - Junho Hwang
- Department of Mechanical Engineering, The University of Tokyo, Tokyo 113-8656, Japan
| | - Hirofumi Daiguji
- Department of Mechanical Engineering, The University of Tokyo, Tokyo 113-8656, Japan
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9
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Startsev MA, Ostrowski M, Goldys EM, Inglis DW. A mobility shift assay for DNA detection using nanochannel gradient electrophoresis. Electrophoresis 2016; 38:335-341. [PMID: 27515373 DOI: 10.1002/elps.201600358] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 08/02/2016] [Accepted: 08/03/2016] [Indexed: 12/18/2022]
Abstract
Conventional detection of pathogenic or other biological contamination relies on amplification of DNA using sequence-specific primers. Recent work in nanofluidics has shown very high concentration enhancement of biomolecules with some degree of simultaneous separation. This work demonstrates the combination of these two approaches by selectively concentrating a mobility-shifted hybridization product, potentially enabling rapid detection of rare DNA fragments such as highly specific 16S ribosomal DNA. We have performed conductivity gradient electrofocusing within nanofluidic channels and have shown concentration of hybridized peptide nucleic acids and DNA oligomers. We also show selectivity to single base-pair mismatch on 18-mer oligos. This approach may enable sensitive optical detection of small amounts of DNA.
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Affiliation(s)
- Michael A Startsev
- Department of Physics and Astronomy, Macquarie University, Sydney, Australia
| | - Martin Ostrowski
- Department of Chemistry and Bimolecular Sciences, Macquarie University, Sydney, Australia
| | - Ewa M Goldys
- Department of Physics and Astronomy, Macquarie University, Sydney, Australia
| | - David W Inglis
- Department of Engineering, Macquarie University, Sydney, Australia
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10
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Hsu WL, Daiguji H, Dunstan DE, Davidson MR, Harvie DJ. Electrokinetics of the silica and aqueous electrolyte solution interface: Viscoelectric effects. Adv Colloid Interface Sci 2016; 234:108-131. [PMID: 27217082 DOI: 10.1016/j.cis.2016.05.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 04/21/2016] [Accepted: 05/02/2016] [Indexed: 10/21/2022]
Abstract
The manipulation of biomolecules, fluid and ionic current in a new breed of integrated nanofluidic devices requires a quantitative understanding of electrokinetics at the silica/water interface. The conventional capacitor-based electrokinetic Electric Double Layer (EDL) models for this interface have some known shortcomings, as evidenced by a lack of consistency within the literature for the (i) equilibrium constants of surface silanol groups, (ii) Stern layer capacitance, (iii) zeta (ζ) potential measured by various electrokinetic methods, and (iv) surface conductivity. In this study, we consider how the experimentally observable viscoelectric effect - that is, the increase of the local viscosity due to the polarisation of polar solvents - affects electrokinetcs at the silica/water interface. Specifically we consider how a model that considers viscoelectric effects (the VE model) performs against two conventional electrokinetic models, namely the Gouy-Chapman (GC) and Basic Stern capacitance (BS) models, in predicting four fundamental electrokinetic phenomena: electrophoresis, electroosmosis, streaming current and streaming potential. It is found that at moderate to high salt concentrations (>5×10(-3)M) predictions from the VE model are in quantitative agreement with experimental electrokinetic measurements when the sole additional adjustable parameter, the viscoelectric coefficient, is set equal to a value given by a previous independent measurement. In contrast neither the GS nor BS models is able to reproduce all experimental data over the same concentration range using a single, robust set of parameters. Significantly, we also show that the streaming current and potential in the moderate to high surface charge range are insensitive to surface charge behaviour (including capacitances) when viscoelectric effects are considered, in difference to models that do not consider these effects. This strongly questions the validity of using pressure based electrokinetic experiments to measure surface charge characteristics within this experimentally relevant high pH and moderate to high salt concentration range. At low salt concentrations (<5×10(-3)M) we find that there is a lack of consistency in previously measured channel conductivities conducted under similar solution conditions (pH, salt concentration), preventing a conclusive assessment of any model suitability in this regime.
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11
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Exploring Gradients in Electrophoretic Separation and Preconcentration on Miniaturized Devices. SEPARATIONS 2016. [DOI: 10.3390/separations3020012] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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12
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Ye Z, Li S, Wang C, Shen R, Wen W. Capillary flow control in nanochannels via hybrid surface. RSC Adv 2016. [DOI: 10.1039/c5ra22033e] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We report a simple and effective approach to control the speed of capillary flow in nanochannels in a quantitative manner.
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Affiliation(s)
- Ziran Ye
- Department of Physics
- The Hong Kong University of Science and Technology
- Kowloon
- Hong Kong
| | - Shunbo Li
- School of Chemistry
- University of Leeds
- Leeds
- UK
| | - Cong Wang
- Department of Physics
- The Hong Kong University of Science and Technology
- Kowloon
- Hong Kong
| | - Rong Shen
- Institute of Physics
- Chinese Academy of Sciences
- Beijing
- China
| | - Weijia Wen
- Department of Physics
- The Hong Kong University of Science and Technology
- Kowloon
- Hong Kong
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13
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Ma Y, Yeh LH, Lin CY, Mei L, Qian S. pH-Regulated Ionic Conductance in a Nanochannel with Overlapped Electric Double Layers. Anal Chem 2015; 87:4508-14. [DOI: 10.1021/acs.analchem.5b00536] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Yu Ma
- School
of Energy Science and Engineering, Harbin Institute of Technology, Harbin 150001, P. R. China
| | - Li-Hsien Yeh
- Department
of Chemical and Materials Engineering, National Yunlin University of Science and Technology, Yunlin 64002, Taiwan
| | - Chih-Yuan Lin
- Institute
of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
| | - Lanju Mei
- Institute
of Micro/Nanotechnology, Old Dominion University, Norfolk, Virginia 23529, United States
| | - Shizhi Qian
- Institute
of Micro/Nanotechnology, Old Dominion University, Norfolk, Virginia 23529, United States
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14
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Mei L, Yeh LH, Qian S. Buffer effect on the ionic conductance in a pH-regulated nanochannel. Electrochem commun 2015. [DOI: 10.1016/j.elecom.2014.12.020] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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15
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Breadmore MC, Tubaon RM, Shallan AI, Phung SC, Abdul Keyon AS, Gstoettenmayr D, Prapatpong P, Alhusban AA, Ranjbar L, See HH, Dawod M, Quirino JP. Recent advances in enhancing the sensitivity of electrophoresis and electrochromatography in capillaries and microchips (2012-2014). Electrophoresis 2015; 36:36-61. [DOI: 10.1002/elps.201400420] [Citation(s) in RCA: 132] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Revised: 09/25/2014] [Accepted: 09/25/2014] [Indexed: 12/15/2022]
Affiliation(s)
- Michael C. Breadmore
- School of Physical Science; Australian Centre of Research on Separation Science, University of Tasmania; Hobart Tasmania Australia
| | - Ria Marni Tubaon
- School of Physical Science; Australian Centre of Research on Separation Science, University of Tasmania; Hobart Tasmania Australia
| | - Aliaa I. Shallan
- School of Physical Science; Australian Centre of Research on Separation Science, University of Tasmania; Hobart Tasmania Australia
| | - Sui Ching Phung
- School of Physical Science; Australian Centre of Research on Separation Science, University of Tasmania; Hobart Tasmania Australia
| | - Aemi S. Abdul Keyon
- School of Physical Science; Australian Centre of Research on Separation Science, University of Tasmania; Hobart Tasmania Australia
- Faculty of Science; Department of Chemistry, Universiti Teknologi Malaysia; Johor Malaysia
| | - Daniel Gstoettenmayr
- School of Physical Science; Australian Centre of Research on Separation Science, University of Tasmania; Hobart Tasmania Australia
| | - Pornpan Prapatpong
- Faculty of Pharmacy; Department of Pharmaceutical Chemistry, Mahidol University; Rajathevee Bangkok Thailand
| | - Ala A. Alhusban
- Faculty of Health Sciences, School of Pharmacy; Australian Centre of Research on Separation Science, University of Tasmania; Hobart Tasmania Australia
| | - Leila Ranjbar
- School of Physical Science; Australian Centre of Research on Separation Science, University of Tasmania; Hobart Tasmania Australia
| | - Hong Heng See
- School of Physical Science; Australian Centre of Research on Separation Science, University of Tasmania; Hobart Tasmania Australia
- Ibnu Sina Institute for Fundamental Science Studies; Universiti Teknologi Malaysia; Johor Malaysia
| | - Mohamed Dawod
- Department of Chemistry; University of Michigan; Ann Arbor MI USA
- Faculty of Pharmacy; Department of Analytical Chemistry, Al-Azhar University; Cairo Egypt
| | - Joselito P. Quirino
- School of Physical Science; Australian Centre of Research on Separation Science, University of Tasmania; Hobart Tasmania Australia
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Hsu WL, Harvie DJE, Davidson MR, Jeong H, Goldys EM, Inglis DW. Concentration gradient focusing and separation in a silica nanofluidic channel with a non-uniform electroosmotic flow. LAB ON A CHIP 2014; 14:3539-49. [PMID: 25027204 DOI: 10.1039/c4lc00504j] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The simultaneous concentration gradient focusing and separation of proteins in a silica nanofluidic channel of various geometries is investigated experimentally and theoretically. Previous modelling of a similar device [Inglis et al., Angew. Chem. Int. Ed., 2011, 50, 7546] assumed a uniform velocity profile along the length of the nanochannel. Using detailed numerical analysis incorporating charge regulation and viscoelectric effects, we show that in reality the varying axial electric field and varying electric double layer thickness caused by the concentration gradient, induce a highly non-uniform velocity profile, fundamentally altering the protein trapping mechanism: the direction of the local electroosmotic flow reverses and two local vortices are formed near the centreline of the nanochannel at the low salt concentration end, enhancing trapping efficiency. Simulation results for yellow/red fluorescent protein R-PE concentration enhancement, peak focusing position and peak focusing width are in good agreement with experimental measurements, validating the model. The predicted separation of yellow/red (R-PE) from green (Dyl-Strep) fluorescent proteins mimics that from a previous experiment [Inglis et al., Angew. Chem. Int. Ed., 2011, 50, 7546] conducted in a slightly different geometry. The results will inform the design of new class of matrix-free particle focusing and separation devices.
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Affiliation(s)
- Wei-Lun Hsu
- Department of Chemical and Biomolecular Engineering, University of Melbourne, VIC 3010, Australia.
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17
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Hsu WL, Inglis DW, Startsev MA, Goldys EM, Davidson MR, Harvie DJE. Isoelectric focusing in a silica nanofluidic channel: effects of electromigration and electroosmosis. Anal Chem 2014; 86:8711-8. [PMID: 25098739 DOI: 10.1021/ac501875u] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Isoelectric focusing of proteins in a silica nanofluidic channel filled with citric acid and disodium phosphate buffers is investigated via numerical simulation. Ions in the channel migrate in response to (i) the electric field acting on their charge and (ii) the bulk electroosmotic flow (which is directed toward the cathode). Proteins are focused near the low pH (anode) end when the electromigration effect is more significant and closer to the high pH (cathode) end when the electroosmotic effect dominates. We simulate the focusing behavior of Dylight labeled streptavidin (Dyl-Strep) proteins in the channel, using a relationship between the protein's charge and pH measured in a previous experiment. Protein focusing results compare well to previous experimental measurements. The effect of some key parameters, such as applied voltage, isoelectric point (pI), bulk pH, and bulk conductivity, on the protein trapping behavior in a nanofluidic channel is examined.
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Affiliation(s)
- Wei-Lun Hsu
- Department of Chemical and Biomolecular Engineering, University of Melbourne , Parkville, Victoria 3010, Australia
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