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Ma X, Kong S, Li Z, Zhen S, Sun F, Yang N. Effect of cross-linking density on the rheological behavior of ultra-soft chitosan microgels at the oil-water interface. J Colloid Interface Sci 2024; 672:574-588. [PMID: 38852358 DOI: 10.1016/j.jcis.2024.06.026] [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: 01/03/2024] [Revised: 06/02/2024] [Accepted: 06/03/2024] [Indexed: 06/11/2024]
Abstract
In this paper, microgels with uniform particle size were prepared by physically cross-linking the hydrophobically modified chitosan (h-CS) with sodium phytate (SP). The effects of cross-linking density on the interfacial adsorption kinetics, viscoelasticity, stress relaxation, and micorheological properties of the hydrophobically modified chitosan microgels (h-CSMs) at the oil-water interface were extensively investigated by the dilatational rheology, compressional rheology, and particle tracing microrheology. The results were correlated with the particle size, morphology, and elasticity of the microgels characterized by dynamic light scattering and atomic force microscopy. It was found that with the increase of cross-linking density, the h-CSMs changed from a polymer-like state to ultra-soft fussy spheres with higher elastic modulus. The compression isotherms demonstrated multi-stage increase caused by the interaction between the shells and that between the cores of the microgels successively. As the increase of cross-linking density, the h-CSMs diffused slower to the oil-water interface, but demonstrating faster permeation adsorption and rearrangement at the oil-water interface, finally forming interfacial layers of higher viscoelastic modulus due to the core-core interaction. Both the initial tension relaxation and the microgel rearrangement after interface expansion became faster as the microgel elasticity increased. The interfacial microrheology demonstrated dynamic caging effect caused by neighboring microgels. This article provides a more comprehensive understanding of the behaviors of polysaccharide microgels at the oil-water interface.
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Affiliation(s)
- Xuxi Ma
- Glyn O. Phillips Hydrocolloid Research Centre, National "111" Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering (Ministry of Education), Key Laboratory of Industrial Microbiology in Hubei, Department of Bioengineering and Food Science, Hubei University of Technology, Wuhan 430068, China
| | - Songmei Kong
- Glyn O. Phillips Hydrocolloid Research Centre, National "111" Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering (Ministry of Education), Key Laboratory of Industrial Microbiology in Hubei, Department of Bioengineering and Food Science, Hubei University of Technology, Wuhan 430068, China
| | - Zhenzhen Li
- Glyn O. Phillips Hydrocolloid Research Centre, National "111" Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering (Ministry of Education), Key Laboratory of Industrial Microbiology in Hubei, Department of Bioengineering and Food Science, Hubei University of Technology, Wuhan 430068, China
| | - Shiyu Zhen
- Glyn O. Phillips Hydrocolloid Research Centre, National "111" Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering (Ministry of Education), Key Laboratory of Industrial Microbiology in Hubei, Department of Bioengineering and Food Science, Hubei University of Technology, Wuhan 430068, China
| | - Fusheng Sun
- Glyn O. Phillips Hydrocolloid Research Centre, National "111" Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering (Ministry of Education), Key Laboratory of Industrial Microbiology in Hubei, Department of Bioengineering and Food Science, Hubei University of Technology, Wuhan 430068, China; Food Hydrocolloid International Science and Technology Cooperation Base of Hubei Province, Hubei University of Technology, Wuhan 430068, China
| | - Nan Yang
- Glyn O. Phillips Hydrocolloid Research Centre, National "111" Center for Cellular Regulation and Molecular Pharmaceutics, Key Laboratory of Fermentation Engineering (Ministry of Education), Key Laboratory of Industrial Microbiology in Hubei, Department of Bioengineering and Food Science, Hubei University of Technology, Wuhan 430068, China; Food Hydrocolloid International Science and Technology Cooperation Base of Hubei Province, Hubei University of Technology, Wuhan 430068, China.
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2
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Gerelli Y, Camerin F, Bochenek S, Schmidt MM, Maestro A, Richtering W, Zaccarelli E, Scotti A. Softness matters: effects of compression on the behavior of adsorbed microgels at interfaces. SOFT MATTER 2024; 20:3653-3665. [PMID: 38623629 DOI: 10.1039/d4sm00235k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/17/2024]
Abstract
Deformable colloids and macromolecules adsorb at interfaces as they decrease the interfacial energy between the two media. The deformability, or softness, of these particles plays a pivotal role in the properties of the interface. In this study, we employ a comprehensive in situ approach, combining neutron reflectometry with molecular dynamics simulations, to thoroughly examine the profound influence of softness on the structure of microgel Langmuir monolayers under compression. Lateral compression of both hard and soft microgel particle monolayers induces substantial structural alterations, leading to an amplified protrusion of the microgels into the aqueous phase. However, a critical distinction emerges: hard microgels are pushed away from the interface, in stark contrast to the soft ones, which remain firmly anchored to it. Concurrently, on the air-exposed side of the monolayer, lateral compression induces a flattening of the surface of the hard monolayer. This phenomenon is not observed for the soft particles as the monolayer is already extremely flat even in the absence of compression. These findings significantly advance our understanding of the key role of softness on both the equilibrium phase behavior of the monolayer and its effect when soft colloids are used as stabilizers of responsive interfaces and emulsions.
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Affiliation(s)
- Yuri Gerelli
- Italian National Research Council - Institute for Complex Systems (CNR-ISC) and Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 2, 00185 Rome, Italy.
| | - Fabrizio Camerin
- Division of Physical Chemistry, Lund University, P. O. Box 124, SE-22100 Lund, Sweden.
| | - Steffen Bochenek
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany
| | - Maximilian M Schmidt
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany
| | - Armando Maestro
- Centro de Física de Materiales (CSIC, UPV/EHU) - Materials Physics Center MPC, Paseo Manuel de Lardizabal 5, E-20018 San Sebastián, Spain
- IKERBASQUE-Basque Foundation for Science, Plaza Euskadi 5, Bilbao, 48009, Spain
- Institut Laue-Langevin, 71 Avenue des Martyrs, 38042 Grenoble, France
| | - Walter Richtering
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany
| | - Emanuela Zaccarelli
- Italian National Research Council - Institute for Complex Systems (CNR-ISC) and Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 2, 00185 Rome, Italy.
| | - Andrea Scotti
- Department of Biomedical Science, Faculty of Health and Society, Malmö University, SE-205 06 Malmö, Sweden.
- Biofilms - Research Center for Biointerfaces, Malmö University, SE-205 06 Malmö, Sweden
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3
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Simons J, Hazra N, Petrunin AV, Crassous JJ, Richtering W, Hohenschutz M. Nonionic Microgels Adapt to Ionic Guest Molecules: Superchaotropic Nanoions. ACS NANO 2024; 18:7546-7557. [PMID: 38417118 DOI: 10.1021/acsnano.3c12357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/01/2024]
Abstract
Microgels are commonly applied as solute carriers, where the size, density, and functionality of the microgels depend on solute binding. As representatives for ionic solutes with high affinity for the microgel, we study here the effect of superchaotropic Keggin polyoxometalates (POMs) PW12O403- (PW) and SiW12O404- (SiW) on the aqueous swelling and internal structure of nonionic poly(N-isopropylacrylamide) (pNiPAM) microgels by light scattering techniques and small-angle X-ray scattering. Due to their weak hydration, these POMs bind spontaneously to the microgels at millimolar concentrations. The microgels thus become charged and swell at low POM concentration, surprisingly without strongly increasing the volume phase transition temperature, and deswell at higher POM concentration. The swelling arises because of the osmotic pressure of dissociated counterions of the POMs, while the deswelling is due to POMs acting as physical cross-links in the microgels under screened electrostatics in NaCl or excess POM solution. This swelling/deswelling transition is sharper for PW than for SiW related to the lower charge density, weaker hydration, and stronger binding of PW. The POMs elicit qualitatively and quantitatively different swelling effects from ionic surfactants and classical salts. Moreover, the network softness and topology govern the swelling response upon POM binding. The softer the microgel, the stronger is the swelling response, while, inside the microgel, regions of high polymer density swell/contract more upon electric charging/cross-linking than regions with low polymer density. POM binding thus enables fine-tuning of microgel properties and highlights the role of network topology in microgel swelling. Because POMs decompose at an alkaline pH, these POM/microgel systems also exhibit pH-responsive swelling in addition to the typical temperature responsiveness of pNiPAM microgels.
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Affiliation(s)
- Jasmin Simons
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, DE-52074 Aachen, Germany
| | - Nabanita Hazra
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, DE-52074 Aachen, Germany
| | - Alexander V Petrunin
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, DE-52074 Aachen, Germany
| | - Jérôme J Crassous
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, DE-52074 Aachen, Germany
| | - Walter Richtering
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, DE-52074 Aachen, Germany
| | - Max Hohenschutz
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, DE-52074 Aachen, Germany
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4
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Schmidt MM, Ruiz-Franco J, Bochenek S, Camerin F, Zaccarelli E, Scotti A. Interfacial Fluid Rheology of Soft Particles. PHYSICAL REVIEW LETTERS 2023; 131:258202. [PMID: 38181345 DOI: 10.1103/physrevlett.131.258202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 08/18/2023] [Accepted: 11/20/2023] [Indexed: 01/07/2024]
Abstract
In situ interfacial rheology and numerical simulations are used to investigate microgel monolayers in a wide range of packing fractions, ζ_{2D}. The heterogeneous particle compressibility determines two flow regimes characterized by distinct master curves. To mimic the microgel architecture and reproduce experiments, an interaction potential combining a soft shoulder with the Hertzian model is introduced. In contrast to bulk conditions, the elastic moduli vary nonmonotonically with ζ_{2D} at the interface, confirming long-sought predictions of reentrant behavior for Hertzian-like systems.
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Affiliation(s)
- Maximilian M Schmidt
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52074 Aachen, Germany
| | - José Ruiz-Franco
- Laboratory of Physical Chemistry and Soft Matter, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Steffen Bochenek
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52074 Aachen, Germany
| | - Fabrizio Camerin
- Soft Condensed Matter & Biophysics, Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 1, 3584 CC Utrecht, The Netherlands
| | - Emanuela Zaccarelli
- Italian National Research Council-Institute for Complex Systems (CNR-ISC), Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 2, 00185 Rome, Italy
| | - Andrea Scotti
- Department of Biomedical Science, Faculty of Health and Society, Malmö University, SE-205 06 Malmö, Sweden
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5
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Bochenek S, Rudov AA, Sassmann T, Potemkin II, Richtering W. Influence of Architecture on the Interfacial Properties of Polymers: Linear Chains, Stars, and Microgels. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:18354-18365. [PMID: 38059308 DOI: 10.1021/acs.langmuir.3c02470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/08/2023]
Abstract
Surface-active polymers have important applications as effective and responsive emulsifiers, foaming agents, and coatings. In this contribution, we explore the impact of the polymer architecture on the behavior at oil-water interfaces by comparing different poly(N-isopropylacrylamide) (pNIPAM)-based systems, namely, monolayers of linear and star-shaped macromolecules, ultralow cross-linked, regular cross-linked, and hollow microgels. Compression isotherms were determined experimentally as well as by computer simulations. The latter provides information about the conformational changes of the individual macromolecules as well as the interfacial properties of the monolayer, including the surface structure and the density distribution of an ensemble of interacting macromolecules near an interface. Surprisingly, the isotherms of the linear polymer, of the star polymer, and of the ultralow cross-linked microgel have an identical shape that differs from the isotherms of regular and hollow microgels. We introduced the mass fraction of adsorbed polymer, which gives a measure of the polymer segments contributing to the isotherm in relation to the most flexible architecture, i.e., the linear polymer, and allows a comparison of polymers with different architectures. The data demonstrate that increasing the number of cross-links leads to a significantly lower amount of polymer in the proximity of the interface as the increase in cross-linker reduces the deformability or softness of the polymers at the interface. The volume fraction profiles along the normal to the interface are essentially different in the microgel monolayers as compared to those in the linear and star polymer. The profiles through the microgel contact line and their growth upon initial compression are similar to those of the linear chains. Herewith, the profiles through the center of mass practically do not change upon compression. Therefore, the initial growth in the microgel surface pressure reveals the polymer-like behavior and is related to the deformation of the peripheral part of the microgel. Further compression of the microgel monolayer leads to 3D interactions of the microgels within the aqueous side of the interface and soft colloid-like behavior.
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Affiliation(s)
- Steffen Bochenek
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany, European Union
| | - Andrey A Rudov
- DWI - Leibniz Institute for Interactive Materials, 52056 Aachen, Germany, European Union
| | - Tim Sassmann
- DWI - Leibniz Institute for Interactive Materials, 52056 Aachen, Germany, European Union
| | - Igor I Potemkin
- DWI - Leibniz Institute for Interactive Materials, 52056 Aachen, Germany, European Union
| | - Walter Richtering
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany, European Union
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6
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Rey M, Kolker J, Richards JA, Malhotra I, Glen TS, Li NYD, Laidlaw FHJ, Renggli D, Vermant J, Schofield AB, Fujii S, Löwen H, Clegg PS. Interactions between interfaces dictate stimuli-responsive emulsion behaviour. Nat Commun 2023; 14:6723. [PMID: 37872193 PMCID: PMC10593850 DOI: 10.1038/s41467-023-42379-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 10/10/2023] [Indexed: 10/25/2023] Open
Abstract
Stimuli-responsive emulsions offer a dual advantage, combining long-term storage with controlled release triggered by external cues such as pH or temperature changes. This study establishes that thermo-responsive emulsion behaviour is primarily determined by interactions between, rather than within, interfaces. Consequently, the stability of these emulsions is intricately tied to the nature of the stabilizing microgel particles - whether they are more polymeric or colloidal, and the morphology they assume at the liquid interface. The colloidal properties of the microgels provide the foundation for the long-term stability of Pickering emulsions. However, limited deformability can lead to non-responsive emulsions. Conversely, the polymeric properties of the microgels enable them to spread and flatten at the liquid interface, enabling stimuli-responsive behaviour. Furthermore, microgels shared between two emulsion droplets in flocculated emulsions facilitate stimuli-responsiveness, regardless of their internal architecture. This underscores the pivotal role of microgel morphology and the forces they exert on liquid interfaces in the control and design of stimuli-responsive emulsions and interfaces.
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Affiliation(s)
- Marcel Rey
- School of Physics and Astronomy, The University of Edinburgh, Peter Guthrie Tait Road, Edinburgh, EH9 3FD, UK.
- Department of Physics, University of Gothenburg, SE-41296, Gothenburg, Sweden.
| | - Jannis Kolker
- Institute for Theoretical Physics II: Soft Matter, Heinrich-Heine University Düsseldorf, D-40225, Düsseldorf, Germany
| | - James A Richards
- School of Physics and Astronomy, The University of Edinburgh, Peter Guthrie Tait Road, Edinburgh, EH9 3FD, UK
| | - Isha Malhotra
- Institute for Theoretical Physics II: Soft Matter, Heinrich-Heine University Düsseldorf, D-40225, Düsseldorf, Germany
| | - Thomas S Glen
- School of Physics and Astronomy, The University of Edinburgh, Peter Guthrie Tait Road, Edinburgh, EH9 3FD, UK
| | - N Y Denise Li
- School of Physics and Astronomy, The University of Edinburgh, Peter Guthrie Tait Road, Edinburgh, EH9 3FD, UK
| | - Fraser H J Laidlaw
- School of Physics and Astronomy, The University of Edinburgh, Peter Guthrie Tait Road, Edinburgh, EH9 3FD, UK
| | - Damian Renggli
- Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, 8093, Zürich, Switzerland
| | - Jan Vermant
- Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, 8093, Zürich, Switzerland
| | - Andrew B Schofield
- School of Physics and Astronomy, The University of Edinburgh, Peter Guthrie Tait Road, Edinburgh, EH9 3FD, UK
| | - Syuji Fujii
- Department of Applied Chemistry, Faculty of Engineering, Osaka Institute of Technology, 5-16-1 Omiya, Asahi-ku, Osaka, 535-8585, Japan
- Nanomaterials Microdevices Research Center, Osaka Institute of Technology, 5-16-1 Omiya, Asahi-ku, Osaka, 535-8585, Japan
| | - Hartmut Löwen
- Institute for Theoretical Physics II: Soft Matter, Heinrich-Heine University Düsseldorf, D-40225, Düsseldorf, Germany
| | - Paul S Clegg
- School of Physics and Astronomy, The University of Edinburgh, Peter Guthrie Tait Road, Edinburgh, EH9 3FD, UK
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7
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Akgonullu DZ, Murray BS, Connell SD, Fang Y, Linter B, Sarkar A. Synthetic and biopolymeric microgels: Review of similarities and difference in behaviour in bulk phases and at interfaces. Adv Colloid Interface Sci 2023; 320:102983. [PMID: 37690329 DOI: 10.1016/j.cis.2023.102983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 08/12/2023] [Accepted: 08/14/2023] [Indexed: 09/12/2023]
Abstract
This review discusses the current knowledge of interfacial and bulk interactions of biopolymeric microgels in relation to the well-established properties of synthetic microgels for applications as viscosity modifiers and Pickering stabilisers. We present a timeline showing the key milestones in designing microgels and their bulk/ interfacial performance. Poly(N-isopropylacrylamide) (pNIPAM) microgels have remained as the protagonist in the synthetic microgel domain whilst proteins or polysaccharides have been primarily used to fabricate biopolymeric microgels. Bulk properties of microgel dispersions are dominated by the volume fraction (ϕ) of the microgel particles, but ϕ is difficult to pinpoint, as addressed by many theoretical models. By evaluating recent experimental studies over the last five years, we find an increasing focus on the analysis of microgel elasticity as a key parameter in modulating their packing at the interfaces, within the provinces of both synthetic and biopolymeric systems. Production methods and physiochemical factors shown to influence microgel swelling in the aqueous phase can have a significant impact on their bulk as well as interfacial performance. Compared to synthetic microgels, biopolymer microgels show a greater tendency for polydispersity and aggregation and do not appear to have a core-corona structure. Comprehensive studies of biopolymeric microgels are still lacking, for example, to accurately determine their inter- and intra- particle interactions, whilst a wider variety of techniques need to be applied in order to allow comparisons to real systems of practical usage.
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Affiliation(s)
- Daisy Z Akgonullu
- Food Colloids and Bioprocessing Group, School of Food Science and Nutrition, University of Leeds, UK
| | - Brent S Murray
- Food Colloids and Bioprocessing Group, School of Food Science and Nutrition, University of Leeds, UK
| | - Simon D Connell
- Molecular and Nanoscale Physics Group, School of Physics and Astronomy, University of Leeds, UK
| | - Yuan Fang
- PepsiCo, Valhalla, New York, NY, USA
| | | | - Anwesha Sarkar
- Food Colloids and Bioprocessing Group, School of Food Science and Nutrition, University of Leeds, UK.
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8
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Vialetto J, Camerin F, Ramakrishna SN, Zaccarelli E, Isa L. Exploring the 3D Conformation of Hard-Core Soft-Shell Particles Adsorbed at a Fluid Interface. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2303404. [PMID: 37541434 PMCID: PMC10558683 DOI: 10.1002/advs.202303404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 07/11/2023] [Indexed: 08/06/2023]
Abstract
The encapsulation of a rigid core within a soft polymeric shell allows obtaining composite colloidal particles that retain functional properties, e.g., optical or mechanical. At the same time, it favors their adsorption at fluid interfaces with a tunable interaction potential to realize tailored two-dimensional (2D) materials. Although they have already been employed for 2D assembly, the conformation of single particles, which is essential to define the monolayer properties, has been largely inferred via indirect or ex situ techniques. Here, by means of in situ atomic force microscopy experiments, the authors uncover the interfacial morphology of hard-core soft-shell microgels, integrating the data with numerical simulations to elucidate the role of the core properties, of the shell thicknesses, and that of the grafting density. They identify that the hard core can influence the conformation of the polymer shells. In particular, for the case of small shell thickness, low grafting density, or poor core affinity for water, the core protrudes more into the organic phase, and the authors observe a decrease in-plane stretching of the network at the interface. By rationalizing their general wetting behavior, such composite particles can be designed to exhibit specific inter-particle interactions of importance both for the stabilization of interfaces and for the fabrication of 2D materials with tailored functional properties.
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Affiliation(s)
- Jacopo Vialetto
- Laboratory for Soft Materials and InterfacesDepartment of MaterialsETH ZürichVladimir‐Prelog‐Weg 5Zürich8093Switzerland
- Present address:
Department of Chemistry & CSGIUniversity of Florence, via della Lastruccia 3Sesto FiorentinoFirenzeI‐50019Italy
| | - Fabrizio Camerin
- CNR Institute for Complex SystemsUos SapienzaP.le A. Moro 2Roma00185Italy
- Department of PhysicsSapienza University of RomeP.le A. Moro 2Roma00185Italy
- Soft Condensed Matter & BiophysicsDebye Institute for Nanomaterials ScienceUtrecht UniversityPrincetonplein 1CC Utrecht3584The Netherlands
| | - Shivaprakash N. Ramakrishna
- Laboratory for Soft Materials and InterfacesDepartment of MaterialsETH ZürichVladimir‐Prelog‐Weg 5Zürich8093Switzerland
| | - Emanuela Zaccarelli
- CNR Institute for Complex SystemsUos SapienzaP.le A. Moro 2Roma00185Italy
- Department of PhysicsSapienza University of RomeP.le A. Moro 2Roma00185Italy
| | - Lucio Isa
- Laboratory for Soft Materials and InterfacesDepartment of MaterialsETH ZürichVladimir‐Prelog‐Weg 5Zürich8093Switzerland
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9
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He S, Schog S, Chen Y, Ji Y, Panitz S, Richtering W, Göstl R. Photoinduced Mechanical Cloaking of Diarylethene-Crosslinked Microgels. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2305845. [PMID: 37578840 DOI: 10.1002/adma.202305845] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 08/04/2023] [Indexed: 08/15/2023]
Abstract
The serial connection of multiple stimuli-responses in polymer architectures enables the logically conjunctive gating of functional material processes on demand. Here, a photoswitchable diarylethene (DAE) acts as a crosslinker in poly(N-vinylcaprolactam) microgels and allows the light-induced shift of the volume phase-transition temperature (VPTT). While swollen microgels below the VPTT are susceptible to force and undergo breakage-aggregation processes, collapsed microgels above the VPTT stay intact in mechanical fields induced by ultrasonication. Within a VPTT shift regime, photoswitching of the DAE transfers microgels from the swollen to the collapsed state and thereby gates their response to force as demonstrated by the light-gated activation of an embedded fluorogenic mechanophore. This photoinduced mechanical cloaking system operates on the polymer topology level and is thereby principally universally applicable.
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Affiliation(s)
- Siyang He
- DWI - Leibniz Institute for Interactive Materials, Forckenbeckstraße 50, 52056, Aachen, Germany
- Institute of Technical and Macromolecular Chemistry, RWTH Aachen University, Worringerweg 2, 52074, Aachen, Germany
| | - Simon Schog
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056, Aachen, Germany
| | - Ying Chen
- DWI - Leibniz Institute for Interactive Materials, Forckenbeckstraße 50, 52056, Aachen, Germany
- Institute of Technical and Macromolecular Chemistry, RWTH Aachen University, Worringerweg 2, 52074, Aachen, Germany
| | - Yuxin Ji
- DWI - Leibniz Institute for Interactive Materials, Forckenbeckstraße 50, 52056, Aachen, Germany
- Institute of Technical and Macromolecular Chemistry, RWTH Aachen University, Worringerweg 2, 52074, Aachen, Germany
| | - Sinan Panitz
- DWI - Leibniz Institute for Interactive Materials, Forckenbeckstraße 50, 52056, Aachen, Germany
- Institute of Technical and Macromolecular Chemistry, RWTH Aachen University, Worringerweg 2, 52074, Aachen, Germany
| | - Walter Richtering
- DWI - Leibniz Institute for Interactive Materials, Forckenbeckstraße 50, 52056, Aachen, Germany
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056, Aachen, Germany
| | - Robert Göstl
- DWI - Leibniz Institute for Interactive Materials, Forckenbeckstraße 50, 52056, Aachen, Germany
- Institute of Technical and Macromolecular Chemistry, RWTH Aachen University, Worringerweg 2, 52074, Aachen, Germany
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10
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Petrunin AV, Schmidt MM, Schweins R, Houston JE, Scotti A. Self-Healing of Charged Microgels in Neutral and Charged Environments. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023. [PMID: 37220302 DOI: 10.1021/acs.langmuir.2c03054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The softness of microgels depends on many aspects, such as particle characteristic lengths, sample concentration, chemical composition of the sample, and elastic moduli of the particle. Here, the response to crowding of ionic microgels is studied. Charged and uncharged ionic microgels are studied in concentrated suspensions of both neutral and ionic microgels with the same swollen size. The combination of small-angle X-ray and neutron scattering with contrast variation allows us to probe both the particle-to-particle arrangement and the response of individual ionic microgels to crowding. When the ionic microgels are uncharged, initial isotropic deswelling followed by faceting is observed. Therefore, the ionizable groups in the polymeric network do not affect the response of the ionic microgel to crowding, which is similar to what has been reported for neutral microgels. In contrast, the kind of microgels composing the matrix plays a key role once the ionic microgels are charged. If the matrix is composed of neutral microgels, a pronounced faceting and negligible deswelling is observed. When only charged ionic microgels are present in the suspension, isotropic deswelling without faceting is dominant.
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Affiliation(s)
- Alexander V Petrunin
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52074 Aachen, Germany
| | - Maximilian M Schmidt
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52074 Aachen, Germany
| | - Ralf Schweins
- Institut Laue-Langevin ILL, DS/LSS, 71 Avenue des Martyrs, F-38000 Grenoble, France
| | - Judith E Houston
- European Spallation Source ERIC, Box 176, SE-221 00 Lund, Sweden
| | - Andrea Scotti
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52074 Aachen, Germany
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11
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Hagemans F, Camerin F, Hazra N, Lammertz J, Dux F, Del Monte G, Laukkanen OV, Crassous JJ, Zaccarelli E, Richtering W. Buckling and Interfacial Deformation of Fluorescent Poly( N-isopropylacrylamide) Microgel Capsules. ACS NANO 2023; 17:7257-7271. [PMID: 37053566 DOI: 10.1021/acsnano.2c10164] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Hollow microgels are fascinating model systems at the crossover between polymer vesicles, emulsions, and colloids as they deform, interpenetrate, and eventually shrink at higher volume fraction or when subjected to an external stress. Here, we introduce a system consisting of microgels with a micrometer-sized cavity enabling a straightforward characterization in situ using fluorescence microscopy techniques. Similarly to elastic capsules, these systems are found to reversibly buckle above a critical osmotic pressure, conversely to smaller hollow microgels, which were previously reported to deswell at high volume fraction. Simulations performed on monomer-resolved in silico hollow microgels confirm the buckling transition and show that the presented microgels can be described with a thin shell model theory. When brought to an interface, these microgels, that we define as microgel capsules, strongly deform and we thus propose to utilize them to locally probe interfacial properties within a theoretical framework adapted from the Johnson-Kendall-Roberts (JKR) theory. Besides their capability to sense their environment and to address fundamental questions on the elasticity and permeability of microgel systems, microgel capsules can be further envisioned as model systems mimicking anisotropic responsive biological systems such as red blood and epithelial cells thanks to the possibility offered by microgels to be synthesized with custom-designed properties.
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Affiliation(s)
- Fabian Hagemans
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, DE-52074 Aachen, Germany
| | - Fabrizio Camerin
- CNR-ISC, Sapienza University of Rome, p.le A. Moro 2, 00185 Roma, Italy
- Department of Physics, Sapienza University of Rome, p.le A. Moro 2 00185 Roma, Italy
| | - Nabanita Hazra
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, DE-52074 Aachen, Germany
| | - Janik Lammertz
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, DE-52074 Aachen, Germany
| | - Frédéric Dux
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, DE-52074 Aachen, Germany
| | - Giovanni Del Monte
- CNR-ISC, Sapienza University of Rome, p.le A. Moro 2, 00185 Roma, Italy
- Department of Physics, Sapienza University of Rome, p.le A. Moro 2 00185 Roma, Italy
| | - Olli-Ville Laukkanen
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, DE-52074 Aachen, Germany
- VTT Technical Research Centre of Finland Ltd, Koivurannantie 1, 40400 Jyväskylä, Finland
| | - Jérôme J Crassous
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, DE-52074 Aachen, Germany
| | - Emanuela Zaccarelli
- CNR-ISC, Sapienza University of Rome, p.le A. Moro 2, 00185 Roma, Italy
- Department of Physics, Sapienza University of Rome, p.le A. Moro 2 00185 Roma, Italy
| | - Walter Richtering
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, DE-52074 Aachen, Germany
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12
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Liu W, Zhu Y, Li Y, Han J, Ngai T. Unveiling the structural relaxation of microgel suspensions at hydrophilic and hydrophobic interfaces. J Colloid Interface Sci 2023; 633:948-958. [PMID: 36509038 DOI: 10.1016/j.jcis.2022.11.150] [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: 10/20/2022] [Revised: 11/24/2022] [Accepted: 11/29/2022] [Indexed: 12/12/2022]
Abstract
HYPOTHESIS Poly(N-isopropylacrylamide) (PNIPAM) microgel particles show considerable hydrophilicity below the lower critical solution temperature (LCST) while they become hydrophobic above LCST. We hypothesize that interfacial wettability could tune particle-surface interaction and subsequent structural relaxation of microgel suspensions at interfaces during the volume phase transition. EXPERIMENTS The evanescent-wave scattering images of microgels at hydrophilic and hydrophobic interfaces are analyzed by a density-fluctuation autocorrelation function (δACF) over a wide range of particle volume fraction ϕ. The structural relaxation is characterized by the decay behavior of δACF. The scattering images in bulk are also processed as a comparison. FINDINGS A two-step relaxation decay is observed at both hydrophilic and hydrophobic interfaces. Relative to fast decay, the rate of structural relaxation in slow decay is reduced by a factor of ∼ 500 and ∼ 50 at hydrophilic and hydrophobic interfaces, respectively. The relaxation times obey divergent power-law dependences on intermediate regime of observing length scales at the two interfaces. Besides, the distribution of fluctuation for relaxation time at different local regions reveals that the structural relaxation is much more homogenous at hydrophilic interfaces than that at hydrophobic interfaces, especially at high ϕ.
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Affiliation(s)
- Wei Liu
- The Key Laboratory of Synthetic and Biological Colloids, Ministry of Education & School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, China
| | - Yuwei Zhu
- Department of Chemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China
| | - Yinan Li
- Department of Chemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China
| | - Jie Han
- School of Science and Technology, Hong Kong Metropolitan University, Homantin, Kowloon, Hong Kong, China.
| | - To Ngai
- The Key Laboratory of Synthetic and Biological Colloids, Ministry of Education & School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, China; Department of Chemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China.
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13
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Kühnhammer M, Gräff K, Loran E, Soltwedel O, Löhmann O, Frielinghaus H, von Klitzing R. Structure formation of PNIPAM microgels in foams and foam films. SOFT MATTER 2022; 18:9249-9262. [PMID: 36440620 DOI: 10.1039/d2sm01021f] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Responsive aqueous foams are very interesting from a fundamental point of view and for various applications like foam flooding or foam flotation. In this study thermoresponsive microgels (MGs) made from poly(N-isopropyl-acrylamide) (PNIPAM) with varying cross-linker content, are used as foam stabilisers. The foams obtained are thermoresponsive and can be destabilised by increasing the temperature. The structuring of MGs inside the foam films is investigated with small-angle neutron scattering and in a thin film pressure balance. The foam films are inhomogeneous and form a network-like structure, in which thin and MG depleted zones with a thickness of ca. 30 nm are interspersed in a continuous network of thick MG containing areas with a thickness of several 100 nm. The thickness of this continuous network is related to the elastic modulus of the individual MGs, which was determined by atomic force microscopy indentation experiments. Both, the elastic moduli and foam film thicknesses, indicate a correlation to the network elasticity of the MGs predicted by the affine network model.
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Affiliation(s)
- Matthias Kühnhammer
- Institute for Condensed Matter Physics, Technische Universität Darmstadt, Hochschulstraße 8, 64289 Darmstadt, Germany.
| | - Kevin Gräff
- Institute for Condensed Matter Physics, Technische Universität Darmstadt, Hochschulstraße 8, 64289 Darmstadt, Germany.
| | - Edwin Loran
- Institute for Condensed Matter Physics, Technische Universität Darmstadt, Hochschulstraße 8, 64289 Darmstadt, Germany.
| | - Olaf Soltwedel
- Institute for Condensed Matter Physics, Technische Universität Darmstadt, Hochschulstraße 8, 64289 Darmstadt, Germany.
| | - Oliver Löhmann
- Institute for Condensed Matter Physics, Technische Universität Darmstadt, Hochschulstraße 8, 64289 Darmstadt, Germany.
| | - Henrich Frielinghaus
- Jülich Center for Neutron Science at the Heinz Maier Leibnitz Zentrum, Forschungszentrum Jülich GmbH, Lichtenbergstrasse 1, 85747 Garching, Germany
| | - Regine von Klitzing
- Institute for Condensed Matter Physics, Technische Universität Darmstadt, Hochschulstraße 8, 64289 Darmstadt, Germany.
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14
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Wilms D, Müller J, Urach A, Schröer F, Schmidt S. Specific Binding of Ligand-Functionalized Thermoresponsive Microgels: Effect of Architecture, Ligand Density, and Hydrophobicity. Biomacromolecules 2022; 23:3899-3908. [PMID: 35930738 DOI: 10.1021/acs.biomac.2c00725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The biomolecular interaction of ligand-presenting switchable microgels is studied with respect to the polymer type, composition, and structure of the microgels. Monodisperse microgels are prepared through precipitation polymerization of N-isopropylacrylamide (PNIPAM microgels) or oligo(ethylene glycol methacrylamide)s (POEGMA microgels) in the presence of crosslinkers or in their absence (self-crosslinked). Functionalization with mannose or biotin as model ligands and affinity measurements upon heating/cooling are conducted to obtain mechanistic insights into how the microgel phase transition affects the specific interactions. In particular, we are interested in adjusting the crosslinking, swelling degree, and ligand density of mannose-functionalized microgels to reversibly catch and release mannose binding Escherichia coli by setting the temperature below or above the microgels' volume phase transition temperature (VPTT). The increased mannose density for collapsed microgels above the VPTT results in stronger E. coli binding. Detachment of E. coli by reswelling the microgels below the VPTT is achieved only for self-crosslinked microgels showing a stronger decrease in ligand density compared to microgels with dedicated crosslinkers. Owing to a reduced mannose density in the shell of POEGMA microgels, their E. coli binding was lower compared to PNIPAM microgels, as supported by ultraresolution microscopy. Importantly, an inverse temperature-controlled binding of microgels decorated with hydrophilic mannose and hydrophobic biotin ligands is observed. This indicates that hydrophobic ligands are inaccessible in the collapsed hydrophobic network above the VPTT, whereas hydrophilic mannose units are then enriched at the microgel-water interface and thus are more accessible.
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Affiliation(s)
- Dimitri Wilms
- Institute for Organic Chemistry and Macromolecular Chemistry, Heinrich-Heine-University, Universitätsstraße 1, 40225 Düsseldorf, Germany
| | - Janita Müller
- Institute for Organic Chemistry and Macromolecular Chemistry, Heinrich-Heine-University, Universitätsstraße 1, 40225 Düsseldorf, Germany
| | - Anselm Urach
- Institute for Organic Chemistry and Macromolecular Chemistry, Heinrich-Heine-University, Universitätsstraße 1, 40225 Düsseldorf, Germany
| | - Fabian Schröer
- Institute for Organic Chemistry and Macromolecular Chemistry, Heinrich-Heine-University, Universitätsstraße 1, 40225 Düsseldorf, Germany
| | - Stephan Schmidt
- Institute for Organic Chemistry and Macromolecular Chemistry, Heinrich-Heine-University, Universitätsstraße 1, 40225 Düsseldorf, Germany
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15
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Xu Y, Zhu H, Denduluri A, Ou Y, Erkamp NA, Qi R, Shen Y, Knowles TPJ. Recent Advances in Microgels: From Biomolecules to Functionality. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2200180. [PMID: 35790106 DOI: 10.1002/smll.202200180] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 03/15/2022] [Indexed: 06/15/2023]
Abstract
The emerging applications of hydrogel materials at different length scales, in areas ranging from sustainability to health, have driven the progress in the design and manufacturing of microgels. Microgels can provide miniaturized, monodisperse, and regulatable compartments, which can be spatially separated or interconnected. These microscopic materials provide novel opportunities for generating biomimetic cell culture environments and are thus key to the advances of modern biomedical research. The evolution of the physical and chemical properties has, furthermore, highlighted the potentials of microgels in the context of materials science and bioengineering. This review describes the recent research progress in the fabrication, characterization, and applications of microgels generated from biomolecular building blocks. A key enabling technology allowing the tailoring of the properties of microgels is their synthesis through microfluidic technologies, and this paper highlights recent advances in these areas and their impact on expanding the physicochemical parameter space accessible using microgels. This review finally discusses the emerging roles that microgels play in liquid-liquid phase separation, micromechanics, biosensors, and regenerative medicine.
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Affiliation(s)
- Yufan Xu
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, UK
| | - Hongjia Zhu
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, UK
| | - Akhila Denduluri
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, UK
| | - Yangteng Ou
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, UK
| | - Nadia A Erkamp
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, UK
| | - Runzhang Qi
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, UK
| | - Yi Shen
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, UK
- School of Chemical and Biomolecular Engineering, The University of Sydney, Sydney, NSW, 2006, Australia
- The University of Sydney Nano Institute, University of Sydney, Sydney, NSW, 2006, Australia
| | - Tuomas P J Knowles
- Centre for Misfolding Diseases, Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW, UK
- Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK
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16
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Bochenek S, Camerin F, Zaccarelli E, Maestro A, Schmidt MM, Richtering W, Scotti A. In-situ study of the impact of temperature and architecture on the interfacial structure of microgels. Nat Commun 2022; 13:3744. [PMID: 35768399 PMCID: PMC9243037 DOI: 10.1038/s41467-022-31209-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 06/08/2022] [Indexed: 11/09/2022] Open
Abstract
The structural characterization of microgels at interfaces is fundamental to understand both their 2D phase behavior and their role as stabilizers that enable emulsions to be broken on demand. However, this characterization is usually limited by available experimental techniques, which do not allow a direct investigation at interfaces. To overcome this difficulty, here we employ neutron reflectometry, which allows us to probe the structure and responsiveness of the microgels in-situ at the air-water interface. We investigate two types of microgels with different cross-link density, thus having different softness and deformability, both below and above their volume phase transition temperature, by combining experiments with computer simulations of in silico synthesized microgels. We find that temperature only affects the portion of microgels in water, while the strongest effect of the microgels softness is observed in their ability to protrude into the air. In particular, standard microgels have an apparent contact angle of few degrees, while ultra-low cross-linked microgels form a flat polymeric layer with zero contact angle. Altogether, this study provides an in-depth microscopic description of how different microgel architectures affect their arrangements at interfaces, and will be the foundation for a better understanding of their phase behavior and assembly.
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Affiliation(s)
- Steffen Bochenek
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52074, Aachen, Germany
| | - Fabrizio Camerin
- CNR-ISC, Sapienza University of Rome, Piazzale Aldo Moro 2, 00185, Roma, Italy.,Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 2, 00185, Roma, Italy
| | - Emanuela Zaccarelli
- CNR-ISC, Sapienza University of Rome, Piazzale Aldo Moro 2, 00185, Roma, Italy.,Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 2, 00185, Roma, Italy
| | - Armando Maestro
- Institut Laue-Langevin ILL DS/LSS, 71 Avenue des Martyrs, 38000, Grenoble, France.,Centro de Fısica de Materiales (CSIC, UPV/EHU) - Materials Physics Center MPC, Paseo Manuel de Lardizabal 5, 20018, San Sebastián, Spain.,IKERBASQUE-Basque Foundation for Science, Plaza Euskadi 5, 48009, Bilbao, Spain
| | - Maximilian M Schmidt
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52074, Aachen, Germany
| | - Walter Richtering
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52074, Aachen, Germany
| | - Andrea Scotti
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52074, Aachen, Germany.
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17
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Scotti A, Schulte MF, Lopez CG, Crassous JJ, Bochenek S, Richtering W. How Softness Matters in Soft Nanogels and Nanogel Assemblies. Chem Rev 2022; 122:11675-11700. [PMID: 35671377 DOI: 10.1021/acs.chemrev.2c00035] [Citation(s) in RCA: 36] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Softness plays a key role in determining the macroscopic properties of colloidal systems, from synthetic nanogels to biological macromolecules, from viruses to star polymers. However, we are missing a way to quantify what the term "softness" means in nanoscience. Having quantitative parameters is fundamental to compare different systems and understand what the consequences of softness on the macroscopic properties are. Here, we propose different quantities that can be measured using scattering methods and microscopy experiments. On the basis of these quantities, we review the recent literature on micro- and nanogels, i.e. cross-linked polymer networks swollen in water, a widely used model system for soft colloids. Applying our criteria, we address the question what makes a nanomaterial soft? We discuss and introduce general criteria to quantify the different definitions of softness for an individual compressible colloid. This is done in terms of the energetic cost associated with the deformation and the capability of the colloid to isotropically deswell. Then, concentrated solutions of soft colloids are considered. New definitions of softness and new parameters, which depend on the particle-to-particle interactions, are introduced in terms of faceting and interpenetration. The influence of the different synthetic routes on the softness of nanogels is discussed. Concentrated solutions of nanogels are considered and we review the recent results in the literature concerning the phase behavior and flow properties of nanogels both in three and two dimensions, in the light of the different parameters we defined. The aim of this review is to look at the results on micro- and nanogels in a more quantitative way that allow us to explain the reported properties in terms of differences in colloidal softness. Furthermore, this review can give researchers dealing with soft colloids quantitative methods to define unambiguously which softness matters in their compound.
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Affiliation(s)
- Andrea Scotti
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany, European Union
| | - M Friederike Schulte
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany, European Union
| | - Carlos G Lopez
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany, European Union
| | - Jérôme J Crassous
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany, European Union
| | - Steffen Bochenek
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany, European Union
| | - Walter Richtering
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany, European Union
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18
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Schulte MF, Izak-Nau E, Braun S, Pich A, Richtering W, Göstl R. Microgels react to force: mechanical properties, syntheses, and force-activated functions. Chem Soc Rev 2022; 51:2939-2956. [PMID: 35319064 DOI: 10.1039/d2cs00011c] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Microgels are colloidal polymer networks with high molar mass and properties between rigid particles, flexible macromolecules, and micellar aggregates. Their unique stimuli-responsiveness in conjunction with their colloidal phase behavior render them useful for many applications ranging from engineering to biomedicine. In many scenarios either the microgel's mechanical properties or its interactions with mechanical force play an important role. Here, we firstly explain microgel mechanical properties and how these are measured by atomic force microscopy (AFM), then we equip the reader with the synthetic background to understand how specific architectures and chemical functionalities enable these mechanical properties, and eventually we elucidate how the interaction of force with microgels can lead to the activation of latent functionality. Since the interaction of microgels with force is a multiscale and multidisciplinary subject, we introduce and interconnect the different research areas that contribute to the understanding of this emerging field in this Tutorial Review.
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Affiliation(s)
- M Friederike Schulte
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany.
| | - Emilia Izak-Nau
- DWI - Leibniz Institute for Interactive Materials, Forckenbeckstr. 50, 52056 Aachen, Germany.
| | - Susanne Braun
- DWI - Leibniz Institute for Interactive Materials, Forckenbeckstr. 50, 52056 Aachen, Germany. .,Institute of Technical and Macromolecular Chemistry, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
| | - Andrij Pich
- DWI - Leibniz Institute for Interactive Materials, Forckenbeckstr. 50, 52056 Aachen, Germany. .,Institute of Technical and Macromolecular Chemistry, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany.,Maastricht University, Aachen Maastricht Institute for Biobased Materials (AMIBM), Brightlands Chemelot Campus, 6167 RD Geleen, The Netherlands
| | - Walter Richtering
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany.
| | - Robert Göstl
- DWI - Leibniz Institute for Interactive Materials, Forckenbeckstr. 50, 52056 Aachen, Germany.
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19
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Stratified-structural hydrogel incorporated with magnesium-ion-modified black phosphorus nanosheets for promoting neuro-vascularized bone regeneration. Bioact Mater 2022; 16:271-284. [PMID: 35386320 PMCID: PMC8965728 DOI: 10.1016/j.bioactmat.2022.02.024] [Citation(s) in RCA: 40] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 02/15/2022] [Accepted: 02/17/2022] [Indexed: 12/17/2022] Open
Abstract
Angiogenesis and neurogenesis play irreplaceable roles in bone repair. Although biomaterial implantation that mimics native skeletal tissue is extensively studied, the nerve-vascular network reconstruction is neglected in the design of biomaterials. Our goal here is to establish a periosteum-simulating bilayer hydrogel and explore the efficiency of bone repair via enhancement of angiogenesis and neurogenesis. In this contribution, we designed a bilayer hydrogel platform incorporated with magnesium-ion-modified black phosphorus (BP) nanosheets for promoting neuro-vascularized bone regeneration. Specifically, we incorporated magnesium-ion-modified black phosphorus (BP@Mg) nanosheets into gelatin methacryloyl (GelMA) hydrogel to prepare the upper hydrogel, whereas the bottom hydrogel was designed as a double-network hydrogel system, consisting of two interpenetrating polymer networks composed of GelMA, PEGDA, and β-TCP nanocrystals. The magnesium ion modification process was developed to enhance BP nanosheet stability and provide a sustained release platform for bioactive ions. Our results demonstrated that the upper layer of hydrogel provided a bionic periosteal structure, which significantly facilitated angiogenesis via induction of endothelial cell migration and presented multiple advantages for the upregulation of nerve-related protein expression in neural stem cells (NSCs). Moreover, the bottom layer of the hydrogel significantly promoted bone marrow mesenchymal stem cells (BMSCs) activity and osteogenic differentiation. We next employed the bilayer hydrogel structure to correct rat skull defects. Based on our radiological and histological examinations, the bilayer hydrogel scaffolds markedly enhanced early vascularization and neurogenesis, which prompted eventual bone regeneration and remodeling. Our current strategy paves way for designing nerve-vascular network biomaterials for bone regeneration. Developing a periosteum-simulating bilayer hydrogel to improve the efficiency of neuro-vascularized bone repair. A magnesium-ion-modified black phosphorus (BP) nanosheets incorporated hydrogel platform was designed. Designing nerve-vascular network biomaterials for bone regeneration.
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20
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Gruber A, Joshi AA, Graff P, Cuéllar-Camacho JL, Hedtrich S, Klinger D. Influence of Nanogel Amphiphilicity on Dermal Delivery: Balancing Surface Hydrophobicity and Network Rigidity. Biomacromolecules 2021; 23:112-127. [PMID: 34874701 DOI: 10.1021/acs.biomac.1c01100] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Polymeric nanogels are promising nonirritating nanocarriers for topical delivery applications. However, conventional hydrophilic networks limit encapsulation of hydrophobic therapeutics and hinder tailored interactions with the amphiphilic skin barrier. To address these limitations, we present amphiphilic nanogels containing hydrophilic networks with hydrophobic domains. Two competing factors determine favorable nanogel-skin interactions and need to be balanced through network composition: suitable surface hydrophobicity and low network rigidity (through physical hydrophobic cross-links). To ensure comparability in such investigations, we prepared a library of nanogels with increasing hydrophobic cholesteryl amounts but similar colloidal features. By combining mechanical and surface hydrophobicity tests (atomic force microscopy (AFM)) with dermal delivery experiments on excised human skin, we can correlate an increased delivery efficacy of Nile red to the viable epidermis with a specific network composition, i.e., 20-30 mol % cholesterol. Thus, our nanogel library identifies a specific balance between surface amphiphilicity and network rigidity to guide developments of advanced dermal delivery vehicles.
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Affiliation(s)
- Alexandra Gruber
- Institute of Pharmacy (Pharmaceutical Chemistry), Freie Universität Berlin, Königin-Luise-Straße 2-4, 14195 Berlin, Germany
| | - Aaroh Anand Joshi
- Institute of Pharmacy (Pharmacology and Toxicology), Freie Universität Berlin, Königin-Luise-Straße 2-4, 14195 Berlin, Germany
| | - Patrick Graff
- Institute of Pharmacy (Pharmacology and Toxicology), Freie Universität Berlin, Königin-Luise-Straße 2-4, 14195 Berlin, Germany
| | - José Luis Cuéllar-Camacho
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Takustraße 3, 14195 Berlin, Germany
| | - Sarah Hedtrich
- Institute of Pharmacy (Pharmacology and Toxicology), Freie Universität Berlin, Königin-Luise-Straße 2-4, 14195 Berlin, Germany.,Faculty of Pharmaceutical Sciences, University of British Columbia, Wesbrook Mall, Vancouver, British Columbia V6T1Z3, Canada
| | - Daniel Klinger
- Institute of Pharmacy (Pharmaceutical Chemistry), Freie Universität Berlin, Königin-Luise-Straße 2-4, 14195 Berlin, Germany
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21
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Ribovski L, Hamelmann NM, Paulusse JMJ. Polymeric Nanoparticles Properties and Brain Delivery. Pharmaceutics 2021; 13:2045. [PMID: 34959326 PMCID: PMC8705716 DOI: 10.3390/pharmaceutics13122045] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 11/22/2021] [Accepted: 11/26/2021] [Indexed: 01/04/2023] Open
Abstract
Safe and reliable entry to the brain is essential for successful diagnosis and treatment of diseases, but it still poses major challenges. As a result, many therapeutic approaches to treating disorders associated with the central nervous system (CNS) still only show limited success. Nano-sized systems are being explored as drug carriers and show great improvements in the delivery of many therapeutics. The systemic delivery of nanoparticles (NPs) or nanocarriers (NCs) to the brain involves reaching the neurovascular unit (NVU), being transported across the blood-brain barrier, (BBB) and accumulating in the brain. Each of these steps can benefit from specifically controlled properties of NPs. Here, we discuss how brain delivery by NPs can benefit from careful design of the NP properties. Properties such as size, charge, shape, and ligand functionalization are commonly addressed in the literature; however, properties such as ligand density, linker length, avidity, protein corona, and stiffness are insufficiently discussed. This is unfortunate since they present great value against multiple barriers encountered by the NPs before reaching the brain, particularly the BBB. We further highlight important examples utilizing targeting ligands and how functionalization parameters, e.g., ligand density and ligand properties, can affect the success of the nano-based delivery system.
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Affiliation(s)
| | | | - Jos M. J. Paulusse
- Department of Molecules and Materials, MESA+ Institute for Nanotechnology and TechMed Institute for Health and Biomedical Technologies, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands; (L.R.); (N.M.H.)
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22
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Li G, Varga I, Kardos A, Dobryden I, Claesson PM. Nanoscale Mechanical Properties of Core-Shell-like Poly-NIPAm Microgel Particles: Effect of Temperature and Cross-Linking Density. J Phys Chem B 2021; 125:9860-9869. [PMID: 34428041 DOI: 10.1021/acs.jpcb.1c04173] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Poly-NIPAm microgel particles with two different cross-linking densities were prepared with the classical batch polymerization process. These particles were adsorbed onto modified silica surfaces, and their nanomechanical properties were measured by means of atomic force microscopy. It was found that these particles have a hard core-soft shell structure both below and above the volume transition temperature. The core-shell-like structure appears due to a higher reaction rate of the cross-linker compared to that of the monomer, leading to depletion of cross-linker in the shell region. The microgel beads with lower average cross-linking density were found to be less stiff below the volume transition temperature than the microgel with higher cross-linking density. Increasing the temperature further to just above the volume transition temperature led to lower stiffness of the more highly cross-linked microgel compared to its less cross-linked counterpart. This effect is explained with the more gradual deswelling with temperature for the more cross-linked microgel particles. This phenomenon was confirmed by dynamic light scattering measurements in the bulk phase, which showed that the larger cross-linking density microgel showed a more gradual collapse in aqueous solution as the temperature was increased.
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Affiliation(s)
- Gen Li
- Biotechnology and Health, Department of Chemistry, Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, KTH Royal Institute of Technology, Drottning Kristinas väg 51, SE-100 44 Stockholm, Sweden
| | - Imre Varga
- Institute of Chemistry, Eötvös Loránd University, Pázmány P. s. 1/A, 1117 Budapest, Hungary.,Department of Chemistry, University J. Selyeho, 945 01 Komarno, Slovakia
| | - Attila Kardos
- Institute of Chemistry, Eötvös Loránd University, Pázmány P. s. 1/A, 1117 Budapest, Hungary.,Department of Chemistry, University J. Selyeho, 945 01 Komarno, Slovakia
| | - Illia Dobryden
- Biotechnology and Health, Department of Chemistry, Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, KTH Royal Institute of Technology, Drottning Kristinas väg 51, SE-100 44 Stockholm, Sweden.,Department of Engineering Sciences and Mathematics, Division of Materials Science, Luleå University of Technology, 97187 Luleå, Sweden
| | - Per M Claesson
- Biotechnology and Health, Department of Chemistry, Division of Surface and Corrosion Science, School of Engineering Sciences in Chemistry, KTH Royal Institute of Technology, Drottning Kristinas väg 51, SE-100 44 Stockholm, Sweden.,Division of Bioscience and Materials, RISE Research Institutes of Sweden, Box 5607, SE 114 86 Stockholm, Sweden
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23
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Vialetto J, Camerin F, Grillo F, Ramakrishna SN, Rovigatti L, Zaccarelli E, Isa L. Effect of Internal Architecture on the Assembly of Soft Particles at Fluid Interfaces. ACS NANO 2021; 15:13105-13117. [PMID: 34328717 PMCID: PMC8388124 DOI: 10.1021/acsnano.1c02486] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Monolayers of soft colloidal particles confined at fluid interfaces are at the core of a broad range of technological processes, from the stabilization of responsive foams and emulsions to advanced lithographic techniques. However, establishing a fundamental relation between their internal architecture, which is controlled during synthesis, and their structural and mechanical properties upon interfacial confinement remains an elusive task. To address this open issue, which defines the monolayer's properties, we synthesize core-shell microgels, whose soft core can be chemically degraded in a controlled fashion. This strategy allows us to obtain a series of particles ranging from analogues of standard batch-synthesized microgels to completely hollow ones after total core removal. Combined experimental and numerical results show that our hollow particles have a thin and deformable shell, leading to a temperature-responsive collapse of the internal cavity and a complete flattening after adsorption at a fluid interface. Mechanical characterization shows that a critical degree of core removal is required to obtain soft disk-like particles at an oil-water interface, which present a distinct response to compression. At low packing fractions, the mechanical response of the monolayer is dominated by the outer polymer chains forming a corona surrounding the particles within the interfacial plane, regardless of the presence of a core. By contrast, at high compression, the absence of a core enables the particles to deform in the direction orthogonal to the interface and to be continuously compressed without altering the monolayer structure. These findings show how fine, single-particle architectural control during synthesis can be engineered to determine the interfacial behavior of microgels, enabling one to link particle conformation with the resulting material properties.
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Affiliation(s)
- Jacopo Vialetto
- Laboratory
for Soft Materials and Interfaces, Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, 8093 Zürich, Switzerland
| | - Fabrizio Camerin
- CNR
Institute for Complex Systems, Uos Sapienza, P.le A. Moro 2, 00185 Roma, Italy
- Department
of Basic and Applied Sciences for Engineering, Sapienza University of Rome, via A. Scarpa 14, 00161 Roma, Italy
| | - Fabio Grillo
- Laboratory
for Soft Materials and Interfaces, Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, 8093 Zürich, Switzerland
| | - Shivaprakash N. Ramakrishna
- Laboratory
for Soft Materials and Interfaces, Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, 8093 Zürich, Switzerland
| | - Lorenzo Rovigatti
- CNR
Institute for Complex Systems, Uos Sapienza, P.le A. Moro 2, 00185 Roma, Italy
- Department
of Physics, Sapienza University of Rome, P.le A. Moro 2, 00185 Roma, Italy
| | - Emanuela Zaccarelli
- CNR
Institute for Complex Systems, Uos Sapienza, P.le A. Moro 2, 00185 Roma, Italy
- Department
of Physics, Sapienza University of Rome, P.le A. Moro 2, 00185 Roma, Italy
| | - Lucio Isa
- Laboratory
for Soft Materials and Interfaces, Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, 8093 Zürich, Switzerland
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24
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Büning D, Schumacher J, Helling A, Chakroun R, Ennen-Roth F, Gröschel AH, Thom V, Ulbricht M. Soft synthetic microgels as mimics of mycoplasma. SOFT MATTER 2021; 17:6445-6460. [PMID: 34132722 DOI: 10.1039/d1sm00379h] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Artificial model colloids are of special interest in the development of advanced sterile filters, as they are able to efficiently separate pleomorphic, highly deformable and infectious bacteria such as mycoplasma, which, until now, has been considered rather challenging and laborious. This study presents a full range of different soft to super soft synthetic polymeric microgels, including two types with similar hydrodynamic mean diameter, i.e., 180 nm, and zeta potential, i.e., -25 ± 10 mV, but different deformability, synthesized by inverse miniemulsion terpolymerization of acrylamide, sodium acrylate and N,N'-methylenebisacrylamide. These microgels were characterized by means of dynamic, electrophoretic and static light scattering techniques. In addition, the deformability of the colloids was investigated by filter cake compressibility studies during ultrafiltration in dead-end mode, analogously to a study of real mycoplasma, i.e., Acholeplasma laidlawii, to allow for a direct comparison. The results indicate that the variation of the synthesis parameters, i.e., crosslinker content, polymeric solid content and content of sodium acrylate, has a significant impact on the swelling behavior of the microgels in aqueous solution as well as on their deformability under filtration conditions. A higher density of chemical crosslinking points results in less swollen and more rigid microgels. Furthermore, these parameters determine electrokinetic properties of the more or less permeable colloids. Overall, it is shown that these soft synthetic microgels can be obtained with tailor-made properties, covering the size of smallest species of and otherwise similar to real mycoplasma. This is a relevant first step towards the future use of synthetic microgels as mimics for mycoplasma.
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Affiliation(s)
- Dominic Büning
- Lehrstuhl für Technische Chemie II, Universität Duisburg-Essen, 45117 Essen, Germany.
| | - Jens Schumacher
- Lehrstuhl für Technische Chemie II, Universität Duisburg-Essen, 45117 Essen, Germany.
| | - Alexander Helling
- Sartorius Stedim Biotech GmbH, August-Spindler-Straße 11, 37079 Göttingen, Germany
| | - Ramzi Chakroun
- Institute of Physical Chemistry, University of Münster, Corrensstr. 28-30, 48149 Münster, Germany
| | - Franka Ennen-Roth
- Lehrstuhl für Technische Chemie II, Universität Duisburg-Essen, 45117 Essen, Germany.
| | - Andre H Gröschel
- Institute of Physical Chemistry, University of Münster, Corrensstr. 28-30, 48149 Münster, Germany
| | - Volkmar Thom
- Sartorius Stedim Biotech GmbH, August-Spindler-Straße 11, 37079 Göttingen, Germany
| | - Mathias Ulbricht
- Lehrstuhl für Technische Chemie II, Universität Duisburg-Essen, 45117 Essen, Germany.
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25
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Wilms D, Adler Y, Schröer F, Bunnemann L, Schmidt S. Elastic modulus distribution in poly( N-isopopylacrylamide) and oligo(ethylene glycol methacrylate)-based microgels studied by AFM. SOFT MATTER 2021; 17:5711-5717. [PMID: 34013309 DOI: 10.1039/d1sm00291k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The spatial elastic modulus distribution of microgel networks in presence and absence of bifunctional crosslinkers is studied by AFM. Thermoresponsive poly(N-isopopylacrylamide) (PNIPAM) and poly(2-(2-methoxyethoxy)ethyl methacrylate-co-oligo(ethylene glycol)methacrylate) (P(MEO2MA-co-OEGMA)) microgels are synthesized via precipitation polymerization above their lower critical solution temperature (LCST). High-resolution elastic modulus profiles are acquired using AFM force-indentation mapping of surface-deposited microgels at 25 °C. For both microgel systems, the use of a bifunctional crosslinker leads to a strong elastic modulus gradient with stiff microgel cores and soft networks toward the edge. In absence of a dedicated crosslinker (self-crosslinking), PNIPAM microgels show a homogeneous elastic modulus distribution, whereas self-crosslinked P(MEO2MA-co-OEGMA) microgels still show decreasing elastic moduli from the centre to the edge of the microgels. However, POEGMA microgels without comonomer showed no elastic modulus gradient suggesting that different incorporation rates of MEO2MA and OEGMA result in a radial variation of the polymer segment density. In addition, when varying the molecular weight of OEGMA the overall elastic modulus was affected, possibly due to molecular weight-dependent phase behavior and different reactivity. This shows that quite different microgel architectures can be obtained by the simple "one-pot" precipitation reaction of microgels which may open to new avenues toward advanced applications.
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Affiliation(s)
- Dimitri Wilms
- Institute for Organic Chemistry and Macromolecular Chemistry, Heinrich-Heine-University, Universitätsstr. 1, 40225 Düsseldorf, Germany.
| | - Yanik Adler
- Institute for Organic Chemistry and Macromolecular Chemistry, Heinrich-Heine-University, Universitätsstr. 1, 40225 Düsseldorf, Germany.
| | - Fabian Schröer
- Institute for Organic Chemistry and Macromolecular Chemistry, Heinrich-Heine-University, Universitätsstr. 1, 40225 Düsseldorf, Germany.
| | - Lennart Bunnemann
- Institute for Organic Chemistry and Macromolecular Chemistry, Heinrich-Heine-University, Universitätsstr. 1, 40225 Düsseldorf, Germany.
| | - Stephan Schmidt
- Institute for Organic Chemistry and Macromolecular Chemistry, Heinrich-Heine-University, Universitätsstr. 1, 40225 Düsseldorf, Germany.
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26
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Hannappel Y, Wiehemeier L, Dirksen M, Kottke T, Hellweg T. Smart Microgels from Unconventional Acrylamides. MACROMOL CHEM PHYS 2021. [DOI: 10.1002/macp.202100067] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Yvonne Hannappel
- Physical and Biophysical Chemistry Bielefeld University Universitätsstr. 25 33615 Bielefeld Germany
| | - Lars Wiehemeier
- Physical and Biophysical Chemistry Bielefeld University Universitätsstr. 25 33615 Bielefeld Germany
| | - Maxim Dirksen
- Physical and Biophysical Chemistry Bielefeld University Universitätsstr. 25 33615 Bielefeld Germany
| | - Tilman Kottke
- Physical and Biophysical Chemistry Bielefeld University Universitätsstr. 25 33615 Bielefeld Germany
| | - Thomas Hellweg
- Physical and Biophysical Chemistry Bielefeld University Universitätsstr. 25 33615 Bielefeld Germany
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27
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Liu W, Wu J, Zhu H, He C, Ngai T. A facile evanescent-field imaging approach for monitoring colloidal gel evolution near a surface. SOFT MATTER 2021; 17:4006-4010. [PMID: 33881131 DOI: 10.1039/d1sm00331c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
A facile evanescent-field imaging approach is developed to probe the aggregation behavior of near-wall colloids/clusters during colloidal gel evolution. Total internal reflection microscope (TIRM) images are directly utilized to access the structural relaxation time via density-fluctuation theory. The behaviors of cluster-cluster aggregation and physical aging of the colloidal gel networks are resolved in both time and space under fractal scaling criteria.
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Affiliation(s)
- Wei Liu
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, China. and Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China and College of Food Engineering and Biotechnology, Hanshan Normal University, Chaozhou 521041, China and Department of Chemistry, The Chinese University of Hong Kong, N.T., Shatin, Hong Kong, China.
| | - Jiahao Wu
- Department of Chemistry, The Chinese University of Hong Kong, N.T., Shatin, Hong Kong, China.
| | - Hui Zhu
- College of Food Engineering and Biotechnology, Hanshan Normal University, Chaozhou 521041, China
| | - Chuanxin He
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, China.
| | - To Ngai
- Department of Chemistry, The Chinese University of Hong Kong, N.T., Shatin, Hong Kong, China.
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28
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Liu W, Zhu Y, Zhang T, Zhu H, He C, Ngai T. Microrheology of thermoresponsive poly(N-isopropylacrylamide) microgel dispersions near a substrate surface. J Colloid Interface Sci 2021; 597:104-113. [PMID: 33866206 DOI: 10.1016/j.jcis.2021.03.181] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 03/30/2021] [Accepted: 03/31/2021] [Indexed: 10/21/2022]
Abstract
HYPOTHESIS Relative to the bulk systems, the near-wall (<500 nm) rheological responses of soft poly(N-isopropylacrylamide) (PNIPAM) microgel dispersions may exhibit distinct dependence on the frequency (ω), temperature (T), and effective volume fraction (ϕeff) during the volume phase transitions. The microrheological behaviors are expected to be governed by the near-wall microstructure and its spatial heterogeneity. EXPERIMENTS The combination of active microrheometry (multipole magnetic tweezers) and total internal reflection microscopy (TIRM) was employed to probe the structure-rheology relationships of microgel dispersions near a substrate surface. The ω, T, and ϕeff-dependences of the storage modulus (G'), loss modulus (G"), and softness (J) were analyzed by power-law and Arrhenius-like scaling theories. The fluctuation of J was further analyzed to give a quantitative description of the inhomogeneity in the near-wall regions. FINDINGS (1) Remarkable differences in the rheological behaviors between the bulk and near-wall cases are revealed, where the latter shows a segmented overlap behavior in ϕeff; (2) Five regimes of ϕeff that correspond to distinct physical states of the microgel dispersions are determined; (3) The near-wall local structures exhibit more heterogeneity in the glass and colloidal gel regimes as compared to the liquid regime.
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Affiliation(s)
- Wei Liu
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, China; Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China; College of Food Engineering and Biotechnology, Hanshan Normal University, Chaozhou 521041, China; Department of Chemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China
| | - Yuwei Zhu
- Department of Chemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China
| | - Tong Zhang
- Department of Chemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China
| | - Hui Zhu
- College of Food Engineering and Biotechnology, Hanshan Normal University, Chaozhou 521041, China
| | - Chuanxin He
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, China.
| | - To Ngai
- Department of Chemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China.
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29
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Schulte MF, Bochenek S, Brugnoni M, Scotti A, Mourran A, Richtering W. Stiffness Tomography of Ultra-Soft Nanogels by Atomic Force Microscopy. Angew Chem Int Ed Engl 2021; 60:2280-2287. [PMID: 33459462 PMCID: PMC7898630 DOI: 10.1002/anie.202011615] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Indexed: 01/02/2023]
Abstract
The softness of nanohydrogels results in unique properties and recently attracted tremendous interest due to the multi-functionalization of interfaces. Herein, we study extremely soft temperature-sensitive ultra-low cross-linked (ULC) nanogels adsorbed to the solid/water interface by atomic force microscopy (AFM). The ultra-soft nanogels seem to disappear in classical imaging modes since a sharp tip fully penetrates these porous networks with very low forces in the range of steric interactions (ca. 100 pN). However, the detailed evaluation of Force Volume mode measurements allows us to resolve their overall shape and at the same time their internal structure in all three dimensions. The nanogels exhibit an extraordinary disk-like and entirely homogeneous but extremely soft structure-even softer than polymer brushes. Moreover, the temperature-sensitive nanogels can be switched on demand between the ultra-soft and a very stiff state.
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Affiliation(s)
| | - Steffen Bochenek
- Institute of Physical ChemistryRWTH Aachen UniversityLandoltweg 252056AachenGermany
| | - Monia Brugnoni
- Institute of Physical ChemistryRWTH Aachen UniversityLandoltweg 252056AachenGermany
| | - Andrea Scotti
- Institute of Physical ChemistryRWTH Aachen UniversityLandoltweg 252056AachenGermany
| | - Ahmed Mourran
- DWI—Leibniz Institute for Interactive MaterialsForckenbeckstr. 5052056AachenGermany
| | - Walter Richtering
- Institute of Physical ChemistryRWTH Aachen UniversityLandoltweg 252056AachenGermany
- DWI—Leibniz Institute for Interactive MaterialsForckenbeckstr. 5052056AachenGermany
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30
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Bochenek S, Scotti A, Richtering W. Temperature-sensitive soft microgels at interfaces: air-water versus oil-water. SOFT MATTER 2021; 17:976-988. [PMID: 33284940 DOI: 10.1039/d0sm01774d] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The formation of smart emulsions or foams whose stability can be controlled on-demand by switching external parameters is of great interest for basic research and applications. An emerging group of smart stabilizers are microgels, which are nano- and micro-sized, three-dimensional polymer networks that are swollen by a good solvent. In the last decades, the influence of various external stimuli on the two-dimensional phase behavior of microgels at air- and oil-water interfaces has been studied. However, the impact of the top-phase itself has been barely considered. Here, we present data that directly address the influence of the top-phase on the microgel properties at interfaces. The dimensions of pNIPAM microgels are measured after deposition from two interfaces, i.e., air- and decane-water. While the total in-plane size of the microgel increases with increasing interfacial tension, the portions or fractions of the microgels situated in the aqueous phase are not affected. We correlate the area microgels occupy to the surface tensions of the interfaces, which allows to estimate an elastic modulus. In comparison to nanoindentation measurements, we observe a larger elastic modulus for the microgels. By combining compression, deposition, and visualization, we show that the two-dimensional phase behavior of the microgel monolayers is not altered, although the microgels have a larger total in-plane size at higher interfacial tension.
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Affiliation(s)
- Steffen Bochenek
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany.
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