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Aldakkan BS, Chalmpes N, Qi G, Hammami MA, Kanj MY, Giannelis EP. Synthesis of Raspberry-like Nanoparticles via Surface Grafting of Positively Charged Polyelectrolyte Brushes: Colloidal Stability and Surface Properties. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:5837-5849. [PMID: 38457691 DOI: 10.1021/acs.langmuir.3c03713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/10/2024]
Abstract
A method to synthesize stable, raspberry-like nanoparticles (NPs), using surface grafting of poly(glycidyl methacrylate) (PGMA) brushes on a polystyrene (PS) core with varying grafting densities, is reported. A two-step functionalization reaction of PGMA epoxide groups comprising an amination step first using ethylene diamine and then followed by a quaternization using glycidyltrimethylammonium chloride generates permanently and positively charged polyelectrolyte brushes, which result in both steric and electrostatic stabilization. The dispersion stability of the brush-bearing NPs is dramatically improved compared to that of the pristine PS core in salt solutions at ambient (25 °C) and elevated temperatures (60 °C). Additionally, the grafted polyelectrolyte chains undergo a reversible swelling in the presence of different ionic strength (IS) salts, which modulate the surface properties, including roughness, stiffness, and adhesion. An atomic force microscope under both dry and wet conditions was used to image conformational changes of the polyelectrolyte chains during the swelling and deswelling transitions as well as to probe the nanomechanical properties by analyzing the corresponding force-sample separation curves. The quaternized polyelectrolyte brushes undergo a conformational transition from a collapsed state to a swelled state in the osmotic brush (OB) regime triggered by the osmotic gradient of mobile ions to the interior of the polymer chain. At IS ∼ 1 M, the brushes contract and the globules reform (salted brush state) as evidenced by an increase in the surface roughness and a reduction in the adhesion of the brushes. Beyond IS ∼ 1 M, quartz crystal microbalance with dissipation monitoring measurements show that salt uptake continues to take place predominantly on the exterior surface of the brush since salt adsorption is not accompanied by a size increase as measured by dynamic light scattering. The study adds new insights into our understanding of the behavior of NPs bearing salt-responsive polyelectrolyte brushes with adaptive swelling thresholds that can ultimately modulate surface properties.
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Affiliation(s)
- Bashayer Saad Aldakkan
- Materials Science and Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Nikolaos Chalmpes
- Materials Science and Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Genggeng Qi
- Materials Science and Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Mohamed Amen Hammami
- Materials Science and Engineering, Cornell University, Ithaca, New York 14853, United States
| | - Mazen Yousef Kanj
- College of Petroleum Engineering & Geosciences, King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia
| | - Emmanuel P Giannelis
- Materials Science and Engineering, Cornell University, Ithaca, New York 14853, United States
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2
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Pial TH, Das S. Specific Ion and Electric Field Controlled Diverse Ion Distribution and Electroosmotic Transport in a Polyelectrolyte Brush Grafted Nanochannel. J Phys Chem B 2022; 126:10543-10553. [PMID: 36454705 DOI: 10.1021/acs.jpcb.2c05524] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Controlling ion distribution inside a charged nanochannel is central to using such channels in diverse applications. Here, we show the possibility of using a charged polyelectrolyte (PE) brush-grafted nanochannel for triggering diverse nanoscopic ion distribution and nanofluidic electroosmotic transport by controlling the valence and size of the counterions (that screen the charges of the PE brushes) and the strength of an externally applied axial electric field. We atomistically simulate separate cases of fully charged polyacrylic acid (PAA) brush functionalized nanochannels with Na+, Cs+, Ca2+, Ba2+, and Y3+ counterions screening the PE charges. Four key findings emerge from our simulations. First, we find that the counterions with a greater valence and a smaller size prefer to remain localized inside the brush layer. Second, for the case where there is an added chloride salt with the same cation (as the screening counterions), there are more coions (Cl- ions) in the brush-free bulk than counterions (for counterions Na+, Ca2+, Ba2+, Y3+): this is a manifestation of the overscreening (OS) of the PE brush layer. Contrastingly, the number of Cs+ ions remain higher than the Cl- ions inside the brush-free bulk, ensuring that there is no OS effect for this case. Third, large applied electric field enables a few Na+, Cs+, and Ba2+ counterions to leave the brush layer and to go to the bulk: this makes the OS of the PE brush layer disappear for the cases of PE brushes being screened by the Na+ and Ba2+ ions. On the other hand, no such electric-field-mediated disappearance of OS is observed for the cases of Ca2+ and Y3+ screening counterions; we attribute this to the firm attachment of these counterions to the negatively charged monomers. Free energy associated with a counterion binding to a PE chain corroborates this diversity in the counterion-specific response to the applied electric field. Finally, we demonstrate that such diverse ion distributions, along with specific electric-field-strength-dependent ion properties, lead to (1) electroosmotic (EOS) transport in nanochannels grafted with PAA brushes screened with Cs+ ions to be always counterion dominated, (2) EOS transport in nanochannels grafted with PAA brushes screened with Ca2+ and Y3+ ions to be always coion-dominated, and (3) EOS transport in nanochannels grafted with PAA brushes screened with Na+ and Ba2+ ions to be coion dominated for smaller electric fields and counterion dominated for larger electric fields.
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Affiliation(s)
- Turash Haque Pial
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland20742, United States
| | - Siddhartha Das
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland20742, United States
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3
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Yamamoto A, Ikarashi T, Fukuma T, Suzuki R, Nakahata M, Miyata K, Tanaka M. Ion-specific nanoscale compaction of cysteine-modified poly(acrylic acid) brushes revealed by 3D scanning force microscopy with frequency modulation detection. NANOSCALE ADVANCES 2022; 4:5027-5036. [PMID: 36504747 PMCID: PMC9680925 DOI: 10.1039/d2na00350c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Accepted: 09/14/2022] [Indexed: 06/17/2023]
Abstract
Stimuli-responsive polyelectrolyte brushes adapt their physico-chemical properties according to pH and ion concentrations of the solution in contact. We synthesized a poly(acrylic acid) bearing cysteine residues at side chains and a lipid head group at the terminal, and incorporated them into a phospholipid monolayer deposited on a hydrophobic silane monolayer. The ion-specific, nanoscale response of polyelectrolyte brushes was detected by using three-dimensional scanning force microscopy (3D-SFM) combined with frequency modulation detection. The obtained topographic and mechanical landscapes indicated that the brushes were uniformly stretched, undergoing a gradual transition from the brush to the bulk electrolyte in the absence of divalent cations. When 1 mM calcium ions were added, the brushes were uniformly compacted, exhibiting a sharper brush-to-bulk transition. Remarkably, the addition of 1 mM cadmium ions made the brush surface significantly rough and the mechanical landscape highly heterogeneous. Currently, cadmium-specific nanoscale compaction of the brushes is attributed to the coordination of thiol and carboxyl side chains with cadmium ions, as suggested for naturally occurring, heavy metal binding proteins.
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Affiliation(s)
- Akihisa Yamamoto
- Center for Integrative Medicine and Physics, Institute for Advanced Study, Kyoto University Kyoto 606-8501 Japan
| | - Takahiko Ikarashi
- Division of Nano Life Science, Kanazawa University Kanazawa 920-1192 Japan
| | - Takeshi Fukuma
- Division of Nano Life Science, Kanazawa University Kanazawa 920-1192 Japan
- Nano Life Science Institute (WPI-NanoLSI), Kanazawa University Kanazawa 920-1192 Japan
| | - Ryo Suzuki
- Center for Integrative Medicine and Physics, Institute for Advanced Study, Kyoto University Kyoto 606-8501 Japan
| | - Masaki Nakahata
- Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University Osaka 560-8531 Japan
- Department of Macromolecular Science, Graduate School of Science, Osaka University Osaka 560-0043 Japan
| | - Kazuki Miyata
- Division of Nano Life Science, Kanazawa University Kanazawa 920-1192 Japan
- Nano Life Science Institute (WPI-NanoLSI), Kanazawa University Kanazawa 920-1192 Japan
| | - Motomu Tanaka
- Center for Integrative Medicine and Physics, Institute for Advanced Study, Kyoto University Kyoto 606-8501 Japan
- Physical Chemistry of Biosystems, Institute of Physical Chemistry, Heidelberg University 69120 Heidelberg Germany
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4
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Berlinger SA, Chen X, Yutkin M, Radke CJ. A Two-Phase Model for Adsorption from Solution Using Quartz Crystal Microbalance with Dissipation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:10114-10127. [PMID: 35952658 DOI: 10.1021/acs.langmuir.2c00998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Quartz crystal microbalance with dissipation (QCM-D) conveniently monitors mass and mechanical property changes of thin films on solid substrates with exquisite resolution. QCM-D is frequently used to measure dissolved solute/sol adsorption isotherms and kinetics. Unfortunately, currently available methodologies to interpret QCM-D data treat the adlayer as a homogeneous medium, which does not adequately describe solution-adsorption physics. Tethering of the adsorbate to the solid surface is not explicitly recognized, and the liquid solvent is included in the adsorbate mass, which is especially in error for low coverages. Consequently, the areal mass of adsorbate (i.e., solute adsorption) is overestimated. Further, friction is not considered between the bound adsorbate and the free solvent flowing in the adlayer. To overcome these deficiencies, we develop a two-phase (2P) continuum model that self-consistently determines adsorbate and liquid-solvent contributions and includes friction between the attached adsorbate and flowing liquid solvent. We then compare the proposed 2P model to those of Sauerbrey for a rigid adlayer and Voinova et al. for a viscoelastic-liquid adlayer. Effects of 2P-adlayer properties are examined on QCM-D-measured frequency and dissipation shifts, including adsorbate volume fraction and elasticity, adlayer thickness, and overtone number, thereby guiding data interpretation. We demonstrate that distinguishing between adsorbate adsorption and homogeneous-film adsorption is critical; failing to do so leads to incorrect adlayer mass and physical properties.
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Affiliation(s)
- Sarah A Berlinger
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720 United States
| | - Xunkai Chen
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720 United States
| | - Maxim Yutkin
- Energy Resources and Petroleum Engineering, King Abdullah University of Science and Technology, Thuwal 23955-6900 Saudi Arabia
| | - Clayton J Radke
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720 United States
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5
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Pial TH, Prajapati M, Chava BS, Sachar HS, Das S. Charge-Density-Specific Response of Grafted Polyelectrolytes to Electric Fields: Bending or Tilting? Macromolecules 2022. [DOI: 10.1021/acs.macromol.2c00237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Turash Haque Pial
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, United States
| | - Mihirkumar Prajapati
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, United States
| | - Bhargav Sai Chava
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, United States
| | - Harnoor Singh Sachar
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, United States
| | - Siddhartha Das
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, United States
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6
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Senechal V, Rodriguez-Hernandez J, Drummond C. Electroresponsive Weak Polyelectrolyte Brushes. Macromolecules 2022. [DOI: 10.1021/acs.macromol.1c02377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | | | - Carlos Drummond
- CNRS, CRPP, UMR 5031, Univ. Bordeaux, F-33600 Pessac, France
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7
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Yu M, Guo X, Zhao W, Zhang K. Single-molecule studies reveal the distinction of strong and weak polyelectrolytes in aqueous solutions. Phys Chem Chem Phys 2021; 23:26130-26134. [PMID: 34734610 DOI: 10.1039/d1cp03572j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Polyelectrolytes are an important class of functional polymers that have the advantages of both polymers and electrolytes due to the presence of charges, and have prospective applications in many fields. The charge of the backbone is an important factor affecting the properties of polyelectrolytes. Therefore, the complex interactions caused by the charges in polyelectrolyte solutions pose a challenge to the study of polyelectrolyte systems, and there is no consensus on the distinction between the behavior of strong and weak polyelectrolytes in solution. Based on single-molecule force spectroscopy (SMFS), the distinction of strong and weak polyelectrolytes is clarified for the first time at the single molecular level by comparing the single-chain elasticity in different environments. It is expected that the single-molecule study will provide the theoretical and experimental basis for the further application of polyelectrolytes.
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Affiliation(s)
- Miao Yu
- School of Mechanical Engineering, Sichuan University, Chengdu 610065, China. .,Innovation Method and Creative Design Key Laboratory of Sichuan Province, Chengdu 610065, China
| | - Xin Guo
- School of Mechanical Engineering, Sichuan University, Chengdu 610065, China. .,Innovation Method and Creative Design Key Laboratory of Sichuan Province, Chengdu 610065, China
| | - Wu Zhao
- School of Mechanical Engineering, Sichuan University, Chengdu 610065, China. .,Innovation Method and Creative Design Key Laboratory of Sichuan Province, Chengdu 610065, China
| | - Kai Zhang
- School of Mechanical Engineering, Sichuan University, Chengdu 610065, China. .,Innovation Method and Creative Design Key Laboratory of Sichuan Province, Chengdu 610065, China
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8
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Chun B, Chun MS. Electrostatic Potential Analysis in Polyelectrolyte Brush-Grafted Microchannels Filled with Polyelectrolyte Dispersion. MICROMACHINES 2021; 12:mi12121475. [PMID: 34945324 PMCID: PMC8706125 DOI: 10.3390/mi12121475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 11/25/2021] [Accepted: 11/28/2021] [Indexed: 11/24/2022]
Abstract
In this study, the model framework that includes almost all relevant parameters of interest has been developed to quantify the electrostatic potential and charge density occurring in microchannels grafted with polyelectrolyte brushes and simultaneously filled with polyelectrolyte dispersion. The brush layer is described by the Alexander-de Gennes model incorporated with the monomer distribution function accompanying the quadratic decay. Each ion concentration due to mobile charges in the bulk and fixed charges in the brush layer can be determined by multi-species ion balance. We solved 2-dimensional Poisson–Nernst–Planck equations adopted for simulating electric field with ion transport in the soft channel, by considering anionic polyelectrolyte of polyacrylic acid (PAA). Remarkable results were obtained regarding the brush height, ionization, electrostatic potential, and charge density profiles with conditions of brush, dispersion, and solution pH. The Donnan potential in the brush channel shows several times higher than the surface potential in the bare channel, whereas it becomes lower with increasing PAA concentration. Our framework is fruitful to provide comparative information regarding electrostatic interaction properties, serving as an important bridge between modeling and experiments, and is possible to couple with governing equations for flow field.
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Affiliation(s)
- Byoungjin Chun
- Complex Fluids Laboratory, Advanced Materials Research Division, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea
- Department of Chemical and Biological Engineering, Korea University, Seoul 02841, Korea
| | - Myung-Suk Chun
- Complex Fluids Laboratory, Advanced Materials Research Division, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea
- Biomedical Engineering Department, KIST School, Korea University of Science and Technology, Seoul 02792, Korea
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9
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Sachar HS, Pial TH, Sivasankar VS, Das S. Simultaneous Energy Generation and Flow Enhancement ( Electroslippage Effect) in Polyelectrolyte Brush Functionalized Nanochannels. ACS NANO 2021; 15:17337-17347. [PMID: 34605243 DOI: 10.1021/acsnano.1c05056] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Energy generation through nanofluidics is a topic of great nanotechnological relevance. Here, we conduct all-atom molecular dynamics (MD) simulations of the transport of water and ions in a pressure-driven flow in nanochannels grafted with charged polyelectrolyte (PE) brushes and discover the possibility of simultaneous electrokinetic energy generation and flow enhancement (henceforth denoted as the electroslippage effect). Such PE-brush-functionalized nanochannels have been recently shown to demonstrate an overscreening (OS) effect (characterized by the presence of a greater number of screening counterions within the PE brush layer than needed to screen the PE brush charges), a consequent presence of excess co-ions within the PE brush-free bulk, and a co-ion-driven electroosmotic (EOS) transport in the presence of small to moderate applied axial electric fields. In this study, however, we find that the streaming current, which represents the current generated by the flow-driven downstream advection of the charge imbalance present within the electric double layer (EDL) that screens the PE brush charges, is governed by the migration of the counterions. This stems from the fact that the highest contribution to the overall streaming current arises from the region near the PE brush-water interface (where there is an excess of counterions), while the brush-free bulk yields a hitherto unreported, but small, co-ion-dictated streaming current. This downstream advection of the charge imbalance (and the resultant counterion-driven streaming current) eventually leads to the development of an electric field (streaming electric field) in the direction that is opposite the direction of the counterion-driven streaming current. The streaming current and the streaming electric field interact to generate the electrokinetic energy. Equally important, this streaming electric field induces an EOS transport, which becomes co-ion-driven, due to the presence of excess co-ions in the brush-free bulk. For the case of nanochannels grafted with negatively charged PE brushes, the streaming electric field will be in a direction that is opposite that of the pressure-driven transport, and hence the co-ion (or anion) driven EOS flow will be in the same direction as the pressure-driven transport. On the other hand, for the case of nanochannels grafted with positively charged PE brushes, the streaming electric field will be in the same direction as the pressure-driven flow, and hence the co-ion (or cation) driven EOS flow, will again be in the same direction as the pressure-driven flow. Therefore, whenever there occurs a presence of the OS and the resulting co-ion-driven EOS transport in PE brush grafted nanochannels, regardless of the sign of the charges of the PE brushes, this EOS transport will always aid the pressure-driven transport and will cause the most fascinating increase in the net volume flow rate across the nanochannel cross section, which is the electroslippage effect.
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Affiliation(s)
| | | | | | - Siddhartha Das
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, United States
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10
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Durmaz EN, Sahin S, Virga E, de Beer S, de Smet LCPM, de Vos WM. Polyelectrolytes as Building Blocks for Next-Generation Membranes with Advanced Functionalities. ACS APPLIED POLYMER MATERIALS 2021; 3:4347-4374. [PMID: 34541543 PMCID: PMC8438666 DOI: 10.1021/acsapm.1c00654] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 08/10/2021] [Indexed: 05/06/2023]
Abstract
The global society is in a transition, where dealing with climate change and water scarcity are important challenges. More efficient separations of chemical species are essential to reduce energy consumption and to provide more reliable access to clean water. Here, membranes with advanced functionalities that go beyond standard separation properties can play a key role. This includes relevant functionalities, such as stimuli-responsiveness, fouling control, stability, specific selectivity, sustainability, and antimicrobial activity. Polyelectrolytes and their complexes are an especially promising system to provide advanced membrane functionalities. Here, we have reviewed recent work where advanced membrane properties stem directly from the material properties provided by polyelectrolytes. This work highlights the versatility of polyelectrolyte-based membrane modifications, where polyelectrolytes are not only applied as single layers, including brushes, but also as more complex polyelectrolyte multilayers on both porous membrane supports and dense membranes. Moreover, free-standing membranes can also be produced completely from aqueous polyelectrolyte solutions allowing much more sustainable approaches to membrane fabrication. The Review demonstrates the promise that polyelectrolytes and their complexes hold for next-generation membranes with advanced properties, while it also provides a clear outlook on the future of this promising field.
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Affiliation(s)
- Elif Nur Durmaz
- Membrane
Science and Technology, MESA+ Institute for Nanotechnology, Faculty
of Science and Technology, University of
Twente, Enschede 7500 AE, The Netherlands
| | - Sevil Sahin
- Laboratory
of Organic Chemistry, Wageningen University, 6708 WE Wageningen, The Netherlands
| | - Ettore Virga
- Membrane
Science and Technology, MESA+ Institute for Nanotechnology, Faculty
of Science and Technology, University of
Twente, Enschede 7500 AE, The Netherlands
- Wetsus, European
Centre of Excellence for Sustainable Water
Technology, Oostergoweg
9, 8911 MA Leeuwarden, The Netherlands
| | - Sissi de Beer
- Sustainable
Polymer Chemistry Group, Department of Molecules and Materials MESA+
Institute for Nanotechnology, University
of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Louis C. P. M. de Smet
- Laboratory
of Organic Chemistry, Wageningen University, 6708 WE Wageningen, The Netherlands
| | - Wiebe M. de Vos
- Membrane
Science and Technology, MESA+ Institute for Nanotechnology, Faculty
of Science and Technology, University of
Twente, Enschede 7500 AE, The Netherlands
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11
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Study on the Mechanism of the Reversible Color Change of Polyacrylic Acid Modified Gold Nanoparticles Responding to pH. MATERIALS 2021; 14:ma14133679. [PMID: 34279250 PMCID: PMC8269886 DOI: 10.3390/ma14133679] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 06/06/2021] [Accepted: 06/24/2021] [Indexed: 11/29/2022]
Abstract
In view of various explanations regarding the pH response of the nanocomposite of gold nanoparticles (AuNPs) modified with polyacrylic acid (PAA) molecules in reported literature, in this work, AuNPs with a size of 20 nm saturatedly loaded with PAA molecules (AuNPs-PAAs) were used to investigate the following aspects of this issue. We investigated the effects of pH on the stability of AuNPs-PAAs in the presence of salt, CTAB, poly (sodium styrenesulfonate) (PSS), ethanol, and free PAA, respectively. Common techniques were undertaken to evaluate the stability, including UV-Vis spectroscopy, Zeta potential analysis, and TEM. The results show that AuNPs-PAAs could respond to pH variations, having a reversible aggregation-to-disaggregation, accompanying their Zeta potential change. The proposed corresponding mechanism was that this reversible change was attributes to the net charge variation of AuNPs-PAAs induced by a reversible protonation-to-deprotonation of PAA rather than the conformational change. It was found that salt, CTAB, PSS, and free PAA could strengthen the dispersity of AuNPs-PAAs, even though their absolute Zeta potential values were decreased to small values or dropped to nearly zero. This abnormal phenomenon was explained by solvation. It was also found that AuNPs-PAAs have an opposite pH response in aqueous and ethanol solutions, justifying the solvation effect. All these results revealed the conformational stability of PAAs immobilized on AuNPs. The methods and the findings of this investigation give some new insights to understand the pH-response of AuNPs-PAAs composites and the design of AuNPs-PAAs-based functional sensors.
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12
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Sachar HS, Chava BS, Pial TH, Das S. All-Atom Molecular Dynamics Simulations of the Temperature Response of Densely Grafted Polyelectrolyte Brushes. Macromolecules 2021. [DOI: 10.1021/acs.macromol.1c00922] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Harnoor Singh Sachar
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, United States
| | - Bhargav Sai Chava
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, United States
| | - Turash Haque Pial
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, United States
| | - Siddhartha Das
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, United States
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13
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Mosley RJ, Talarico MV, Byrne ME. Recent applications of QCM-D for the design, synthesis, and characterization of bioactive materials. J BIOACT COMPAT POL 2021. [DOI: 10.1177/08839115211014216] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The clinical translation of bioactive technologies is lacking compared to the number of novel technologies reported in the literature. This is in part due to the difficulties in characterizing bioactive materials to understand and predict their biological response. To progress the field and increase clinical success, more robust analytical techniques must be utilized when investigating novel bioactive materials. The quartz crystal microbalance with dissipation (QCM-D), a label-free sensing instrument based on an acoustic resonator, is used to quantify mass change and viscoelastic parameters from soft materials at the nanoscale, in situ, with precise temporal resolution and operation in both liquid and gaseous environments. The versatility of QCM-D has enhanced the characterization of bioactive polymers and sensing arrays for advanced applications of novel biotechnologies. In this review, we highlight exciting, recent applications of QCM-D for the investigation of bioactive materials. Attention is given to the dynamic mechanical properties of bioactive materials, discerning protein structure on surfaces, probing cell adhesion and cytoskeletal changes, and biosensing applications. We conclude that QCM-D has untapped utility in the pre-clinical investigation of bioactive materials and further utilization can improve the clinical success of novel technologies.
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Affiliation(s)
- Robert J Mosley
- Biomimetic & Biohybrid Materials, Biomedical Devices, and Drug Delivery Laboratories, Department of Biomedical Engineering, Rowan University, Glassboro, NJ, USA
| | - Matthew V Talarico
- Biomimetic & Biohybrid Materials, Biomedical Devices, and Drug Delivery Laboratories, Department of Biomedical Engineering, Rowan University, Glassboro, NJ, USA
| | - Mark E Byrne
- Biomimetic & Biohybrid Materials, Biomedical Devices, and Drug Delivery Laboratories, Department of Biomedical Engineering, Rowan University, Glassboro, NJ, USA
- Department of Chemical Engineering, Rowan University, Glassboro, NJ, USA
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14
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Pial TH, Sachar HS, Desai PR, Das S. Overscreening, Co-Ion-Dominated Electroosmosis, and Electric Field Strength Mediated Flow Reversal in Polyelectrolyte Brush Functionalized Nanochannels. ACS NANO 2021; 15:6507-6516. [PMID: 33797221 DOI: 10.1021/acsnano.0c09248] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Controlling the direction and strength of nanofluidic electrohydrodyanmic transport in the presence of an externally applied electric field is extremely important in a number of nanotechnological applications. Here, we employ all-atom molecular dynamics simulations to discover the possibility of changing the direction of electroosmotic (EOS) liquid flows by merely changing the electric field strength in a nanochannel functionalized with polyelectrolyte (PE) brushes. In exploring this, we have uncovered three facets of nanoconfined PE brush behavior and resulting EOS transport. First, we identify the onset of an overscreening effect: such overscreening refers to the presence of more counterions (Na+) within the brush layer than needed to neutralize the negative brush charges. Accordingly, as a consequence of the overscreening, in the bulk liquid outside the brush layer, there is a greater number of co-ions (Cl-) than counterions in the presence of an added salt (NaCl). Second, this specific ion distribution ensures that the overall EOS flow is along the direction of motion of the co-ions. Such co-ion-dictated EOS transport directly contradicts the notion that EOS flow is always dictated by the motion of the counterions. Finally, for large-enough electric fields, the brush height reduces significantly, causing some of the excess overscreening-inducing counterions to squeeze out of the PE brush layer into the brush-free bulk. As a result, the overscreening effect disappears and the number of co-ions and counterions outside the PE brush layer become similar. Despite that there is an EOS transport, this EOS transport, unlike the standard EOS transport that occurs due to the imbalance of the co-ions and counterions, occurs since a larger residence time of the water molecules in the first solvation shell of the counterions (Na+) ensures a water transport in the direction of motion of the counterions. The net effect is the reversal of the direction of the EOS transport by merely changing the strength of the electric field.
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Affiliation(s)
- Turash Haque Pial
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, United States
| | - Harnoor Singh Sachar
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, United States
| | - Parth Rakesh Desai
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, United States
| | - Siddhartha Das
- Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, United States
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15
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Ehtiati K, Z. Moghaddam S, Daugaard AE, Thormann E. Crucial Nonelectrostatic Effects on Polyelectrolyte Brush Behavior. Macromolecules 2021. [DOI: 10.1021/acs.macromol.0c02526] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Koosha Ehtiati
- Department of Chemistry, Technical University of Denmark, Kgs. Lyngby 2800, Denmark
| | - Saeed Z. Moghaddam
- Department of Chemistry, Technical University of Denmark, Kgs. Lyngby 2800, Denmark
| | - Anders E. Daugaard
- Danish Polymer Center, Department of Chemical and Biochemical Engineering, Technical University of Denmark, Kgs. Lyngby 2800, Denmark
| | - Esben Thormann
- Department of Chemistry, Technical University of Denmark, Kgs. Lyngby 2800, Denmark
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16
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Hollingsworth N, Larson RG. Hysteretic Swelling/Deswelling of Polyelectrolyte Brushes and Bilayer Films in Response to Changes in pH and Salt Concentration. Polymers (Basel) 2021; 13:polym13050812. [PMID: 33800938 PMCID: PMC7961338 DOI: 10.3390/polym13050812] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 02/26/2021] [Accepted: 02/27/2021] [Indexed: 11/26/2022] Open
Abstract
We use a quartz crystal microbalance with dissipation (QCM-D) to investigate the swelling/de-swelling and hysteresis in brushes of weakly ionizable polyanion poly(acrylic acid) (PAA) brushes and bilayers containing a PAA brush and a poly(ethylene imine) (PEI) overlayer. We show that for a long PAA chain (Mw = 39 kDa), at low grafting density (σ < 0.05 chains/nm2) and at a pH value (=4.2) at which it is partially charged, in the low-salt “osmotic brush” regime, the brush height no longer increases with increased grafting density as is seen for shorter brushes and denser grafting, but shows a slight decrease in height, in qualitative agreement with predictions of scaling theory. In a cycle of stepped pH changes, we also show that at a low grafting density of σ = 0.023 chains/nm2 and Mw = 39 kDa, there is hysteresis in swelling over timescales of many minutes. For higher grafting densities σ = 0.87 chains/nm2 and shorter chains (2 kDa), we see little or no measurable hysteresis, and, at intermediate chain length 14 kDa and grafting density σ = 0.06 chains/nm2, hysteresis is observed at short timescales but is greatly reduced at longer timescales. These results are similarly observed when bilayers are made by adsorbing onto the PAA brush a layer of the polycation PEI. In addition, we also note hysteresis in swelling upon changes of salt concentration when pH is fixed. These results show the rich thermodynamics and kinetics of even monolayers and bilayers of polyelectrolyte films.
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Affiliation(s)
- Nisha Hollingsworth
- Department of Macromolecular Science & Engineering, University of Michigan, Ann Arbor, MI 48109, USA;
| | - Ronald G. Larson
- Department of Macromolecular Science & Engineering, University of Michigan, Ann Arbor, MI 48109, USA;
- Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
- Biointerfaces Institute, University of Michigan, Ann Arbor, MI 48109, USA
- Correspondence:
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17
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Walkowiak J, Gradzielski M, Zauscher S, Ballauff M. Interaction of Proteins with a Planar Poly(acrylic acid) Brush: Analysis by Quartz Crystal Microbalance with Dissipation Monitoring (QCM-D). Polymers (Basel) 2020; 13:polym13010122. [PMID: 33396873 PMCID: PMC7795234 DOI: 10.3390/polym13010122] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 12/22/2020] [Accepted: 12/23/2020] [Indexed: 12/27/2022] Open
Abstract
We describe the preparation of a poly(acrylic acid) (PAA) brush, polymerized by atom transfer radical polymerization (ATRP) of tert-butyl acrylate (tBA) and subsequent acid hydrolysis, on the flat gold surfaces of quartz-crystal microbalance (QCM) crystals. The PAA brushes were characterized by Fourier transform infrared (FT-IR) spectroscopy, ellipsometry and water contact angle analysis. The interaction of the PAA brushes with human serum albumin (HSA) was studied for a range of ionic strengths and pH conditions by quartz-crystal microbalance with dissipation monitoring (QCM-D). The quantitative analysis showed a strong adsorption of protein molecules onto the PAA brush. By increasing the ionic strength, we were able to release a fraction of the initially bound HSA molecules. This finding highlights the importance of counterions in the polyelectrolyte-mediated protein adsorption/desorption. A comparison with recent calorimetric studies related to the binding of HSA to polyelectrolytes allowed us to fully analyze the QCM data based on the results of the thermodynamic analysis of the binding process.
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Affiliation(s)
- Jacek Walkowiak
- Aachen-Maastricht Institute for Biobased Materials (AMIBM), Maastricht University, Brightlands Chemelot Campus, Urmonderbaan 22, 6167 RD Geleen, The Netherlands;
| | - Michael Gradzielski
- Stranski Laboratorium für Physikalische Chemie und Theoretische Chemie, Institut für Chemie, Straße des 17. Juni 124, Sekr. TC7, Technische Universität Berlin, 10623 Berlin, Germany;
| | - Stefan Zauscher
- Mechanical Engineering and Material Sciences, Duke University, Durham, NC 27708, USA
- Correspondence: (S.Z.); (M.B.)
| | - Matthias Ballauff
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustraße 3, 14195 Berlin, Germany
- Correspondence: (S.Z.); (M.B.)
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18
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Ferrand-Drake del Castillo G, Hailes RLN, Dahlin A. Large Changes in Protonation of Weak Polyelectrolyte Brushes with Salt Concentration-Implications for Protein Immobilization. J Phys Chem Lett 2020; 11:5212-5218. [PMID: 32515599 PMCID: PMC7467743 DOI: 10.1021/acs.jpclett.0c01289] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 06/09/2020] [Indexed: 05/27/2023]
Abstract
We report for the first time that the protonation behavior of weak polyelectrolyte brushes depends very strongly on ionic strength. The pKa changes by one pH step per order of magnitude in salt concentration. For low salt concentrations (∼1 mM), a very high pH is required to deprotonate a polyacidic brush and a very low pH is required to protonate a polybasic brush. This has major consequences for interactions with other macromolecules, as the brushes are actually almost fully neutral when believed to be charged. We propose that many previous studies on electrostatic interactions between polyelectrolytes and proteins have, in fact, looked at other types of intermolecular forces, in particular, hydrophobic interactions and hydrogen bonds.
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Affiliation(s)
| | | | - Andreas Dahlin
- Department of Chemistry and
Chemical Engineering, Chalmers University
of Technology, 41296 Gothenburg, Sweden
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19
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Ferrand-Drake Del Castillo G, Hailes RLN, Adali-Kaya Z, Robson T, Dahlin A. Generic high-capacity protein capture and release by pH control. Chem Commun (Camb) 2020; 56:5889-5892. [PMID: 32373823 DOI: 10.1039/d0cc01250e] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Techniques for immobilization and release of proteins are of general interest but challenging to develop. Here we show a new method for high-capacity (several μg cm-2) immobilization of proteins in polyelectrolyte brushes by multivalent hydrogen bonds. Upon increasing pH, the proteins are fully released with preserved structure and activity.
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