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Guerrero-Felix JG, Lopez-Miras J, Rodriguez-Valverde MA, Moraila-Martinez CL, Fernandez-Rodriguez MA. Automation of an atomic force microscope via Arduino. HardwareX 2023; 15:e00447. [PMID: 37521147 PMCID: PMC10372894 DOI: 10.1016/j.ohx.2023.e00447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 08/01/2023]
Abstract
The Atomic Force Microscopy is a very versatile technique that allows to characterize surfaces by acquiring topographies with sub-nanometer resolution. This technique often overcomes the problems and capabilities of electron microscopy when characterizing few nanometers thin coatings over solid substrates. They are expensive, in the half million dollar range for standard units, and therefore it is often difficult to upgrade to new units with improved characteristics. One of these improvements, motorization and automation of the measurements is very interesting to sample different parts of a substrate in an unattended way. Here we report a low cost upgrade under 60 $ to a Dimension 3000 AFM based on a control unit using an Arduino Leonardo. It enables to acquire dozens or hundreds of images automatically by mimicking keyboard shortcuts and interfacing the AFM PCI card.
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Affiliation(s)
- Jesus Gerardo Guerrero-Felix
- Department of Applied Physics, Faculty of Sciences, University of Granada, Campus de Fuentenueva s/n, 18071 Granada, Spain
- Faculty of Biology, Autonomous University of Sinaloa, 80010 Culiacan, Sinaloa, Mexico
| | - Javier Lopez-Miras
- Department of Applied Physics, Faculty of Sciences, University of Granada, Campus de Fuentenueva s/n, 18071 Granada, Spain
| | | | - Carmen Lucia Moraila-Martinez
- Faculty of Biology, Autonomous University of Sinaloa, 80010 Culiacan, Sinaloa, Mexico
- Department of Electronics and Computer Technology, Faculty of Sciences, University of Granada, 18071 Granada, Spain
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2
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del Castillo-Santaella T, Maldonado-Valderrama J, Fernandez-Rodriguez MA. Autotitrator based on an Arduino Open Source Pump. HardwareX 2023; 15:e00464. [PMID: 37649586 PMCID: PMC10462874 DOI: 10.1016/j.ohx.2023.e00464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 07/04/2023] [Accepted: 07/30/2023] [Indexed: 09/01/2023]
Abstract
Acid-base titration is a quantitative analysis that enables knowing the quantity of acidic or basic groups present in a solution sample. It consists in the addition of base or acid to the solution sample while monitoring the pH to reach a neutral pH. The titration can be automated and here we present a low cost Arduino based Open Source Pump (OSPump) modified to act as an automated titrator with an obsolete but reliable Metrohm 713 pH meter. Our device is 50 times less expensive than second hand units from the pH meter manufacturer and inherently open to customization. We present two validation cases of study, including the lipolysis of a vegetable olive oil in water emulsion, characterized by the OSPump Titrator.
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Affiliation(s)
- Teresa del Castillo-Santaella
- Department of Applied Physics, Faculty of Sciences, University of Granada, Campus de Fuentenueva s/n, 18071 Granada, Spain
- Department of Physical Chemistry, Faculty of Pharmacy, University of Granada, Campus de Cartuja s/n, 18071 Granada, Spain
| | - Julia Maldonado-Valderrama
- Department of Applied Physics, Faculty of Sciences, University of Granada, Campus de Fuentenueva s/n, 18071 Granada, Spain
- Excellence Research Unit “Modeling Nature” (MNat), University of Granada, Granada, Spain
| | - Miguel Angel Fernandez-Rodriguez
- Department of Applied Physics, Faculty of Sciences, University of Granada, Campus de Fuentenueva s/n, 18071 Granada, Spain
- Excellence Research Unit “Modeling Nature” (MNat), University of Granada, Granada, Spain
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3
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Fernandez-Rodriguez MA, Orozco-Barrera S, Sun W, Gámez F, Caro C, García-Martín ML, Rica RA. Hot Brownian Motion of Thermoresponsive Microgels in Optical Tweezers Shows Discontinuous Volume Phase Transition and Bistability. Small 2023; 19:e2301653. [PMID: 37158287 DOI: 10.1002/smll.202301653] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 04/03/2023] [Indexed: 05/10/2023]
Abstract
Microgels are soft microparticles that often exhibit thermoresponsiveness and feature a transformation at a critical temperature, referred to as the volume phase transition temperature. Whether this transformation occurs as a smooth or as a discontinuous one is still a matter of debate. This question can be addressed by studying individual microgels trapped in optical tweezers. For this aim, composite particles are obtained by decorating Poly-N-isopropylacrylamide (pNIPAM) microgels with iron oxide nanocubes. These composites become self-heating when illuminated by the infrared trapping laser, performing hot Brownian motion within the trap. Above a certain laser power, a single decorated microgel features a volume phase transition that is discontinuous, while the usual continuous sigmoidal-like dependence is recovered after averaging over different microgels. The collective sigmoidal behavior enables the application of a power-to-temperature calibration and provides the effective drag coefficient of the self-heating microgels, thus establishing these composite particles as potential micro-thermometers and micro-heaters. Moreover, the self-heating microgels also exhibit an unexpected and intriguing bistability behavior above the critical temperature, probably due to partial collapses of the microgel. These results set the stage for further studies and the development of applications based on the hot Brownian motion of soft particles.
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Affiliation(s)
- Miguel Angel Fernandez-Rodriguez
- Universidad de Granada, Nanoparticles Trapping Laboratory, Department of Applied Physics, Faculty of Sciences, Campus de Fuentenueva s/n, 18071, Granada, Spain
- Laboratory of Surface and Interface Physics, Department of Applied Physics, Faculty of Sciences, Universidad de Granada, Campus de Fuentenueva s/n, 18071, Granada, Spain
- Research Unit Modeling Nature (MNat), Universidad de Granada, Granada, Spain
| | - Sergio Orozco-Barrera
- Universidad de Granada, Nanoparticles Trapping Laboratory, Department of Applied Physics, Faculty of Sciences, Campus de Fuentenueva s/n, 18071, Granada, Spain
| | - Wei Sun
- Universidad de Granada, Nanoparticles Trapping Laboratory, Department of Applied Physics, Faculty of Sciences, Campus de Fuentenueva s/n, 18071, Granada, Spain
- Department of Physics, Yanshan University, Qinhuangdao, 066004, China
| | - Francisco Gámez
- Universidad de Granada, Nanoparticles Trapping Laboratory, Department of Applied Physics, Faculty of Sciences, Campus de Fuentenueva s/n, 18071, Granada, Spain
| | - Carlos Caro
- Department of Physical Chemistry, Faculty of Chemical Sciences, Complutense University of Madrid, 28040, Madrid, Spain
| | - María L García-Martín
- Department of Physical Chemistry, Faculty of Chemical Sciences, Complutense University of Madrid, 28040, Madrid, Spain
- Instituto de Investigación Bioméadica de Málaga y Plataforma en Nanomedicina (IBIMA Plataforma BIONAND), C/ Severo Ochoa, 35, 29590, Málaga, Spain
- Biomedical Research Networking Center in Bioengineering, Biomaterials & Nanomedicine (CIBER-BBN), 28029, Madrid, Spain
| | - Raúl Alberto Rica
- Universidad de Granada, Nanoparticles Trapping Laboratory, Department of Applied Physics, Faculty of Sciences, Campus de Fuentenueva s/n, 18071, Granada, Spain
- Research Unit Modeling Nature (MNat), Universidad de Granada, Granada, Spain
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4
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Alvarez L, Fernandez-Rodriguez MA, Alegria A, Arrese-Igor S, Zhao K, Kröger M, Isa L. Reconfigurable artificial microswimmers with internal feedback. Nat Commun 2021; 12:4762. [PMID: 34362934 PMCID: PMC8346629 DOI: 10.1038/s41467-021-25108-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 07/17/2021] [Indexed: 11/09/2022] Open
Abstract
Self-propelling microparticles are often proposed as synthetic models for biological microswimmers, yet they lack the internally regulated adaptation of their biological counterparts. Conversely, adaptation can be encoded in larger-scale soft-robotic devices but remains elusive to transfer to the colloidal scale. Here, we create responsive microswimmers, powered by electro-hydrodynamic flows, which can adapt their motility via internal reconfiguration. Using sequential capillary assembly, we fabricate deterministic colloidal clusters comprising soft thermo-responsive microgels and light-absorbing particles. Light absorption induces preferential local heating and triggers the volume phase transition of the microgels, leading to an adaptation of the clusters' motility, which is orthogonal to their propulsion scheme. We rationalize this response via the coupling between self-propulsion and variations of particle shape and dielectric properties upon heating. Harnessing such coupling allows for strategies to achieve local dynamical control with simple illumination patterns, revealing exciting opportunities for developing tactic active materials.
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Affiliation(s)
- L Alvarez
- Laboratory for Soft Materials and Interfaces, Department of Materials, ETH Zurich, Zurich, Switzerland.
| | - M A Fernandez-Rodriguez
- Laboratory for Soft Materials and Interfaces, Department of Materials, ETH Zurich, Zurich, Switzerland
- Biocolloid and Fluid Physics Group, Applied Physics Department, Faculty of Sciences, University of Granada, Granada, Spain
| | - A Alegria
- Centro de Física de Materiales (CSIC-UPV/EHU), Materials Physics Center, San Sebastián, Spain
| | - S Arrese-Igor
- Centro de Física de Materiales (CSIC-UPV/EHU), Materials Physics Center, San Sebastián, Spain
| | - K Zhao
- Laboratory for Soft Materials and Interfaces, Department of Materials, ETH Zurich, Zurich, Switzerland
| | - M Kröger
- Polymer Physics, Department of Materials, ETH Zurich, Zurich, Switzerland
| | - Lucio Isa
- Laboratory for Soft Materials and Interfaces, Department of Materials, ETH Zurich, Zurich, Switzerland.
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5
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Pioli R, Fernandez-Rodriguez MA, Grillo F, Alvarez L, Stocker R, Isa L, Secchi E. Sequential capillarity-assisted particle assembly in a microfluidic channel. Lab Chip 2021; 21:888-895. [PMID: 33427254 DOI: 10.1039/d0lc00962h] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Colloidal patterning enables the placement of a wide range of materials into prescribed spatial arrangements, as required in a variety of applications, including micro- and nano-electronics, sensing, and plasmonics. Directed colloidal assembly methods, which exploit external forces to place particles with high yield and great accuracy, are particularly powerful. However, currently available techniques require specialized equipment, which limits their applicability. Here, we present a microfluidic platform to produce versatile colloidal patterns within a microchannel, based on sequential capillarity-assisted particle assembly (sCAPA). This new microfluidic technology exploits the capillary forces resulting from the controlled motion of an evaporating droplet inside a microfluidic channel to deposit individual particles in an array of traps microfabricated onto a substrate. Sequential depositions allow the generation of a desired spatial layout of colloidal particles of single or multiple types, dictated solely by the geometry of the traps and the filling sequence. We show that the platform can be used to create a variety of patterns and that the microfluidic channel easily allows surface functionalization of trapped particles. By enabling colloidal patterning to be carried out in a controlled environment, exploiting equipment routinely used in microfluidics, we demonstrate an easy-to-build platform that can be implemented in microfluidics labs.
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Affiliation(s)
- Roberto Pioli
- Institute of Environmental Engineering, Department of Civil, Environmental and Geomatic Engineering, ETH Zürich, Stefano-Franscini-Platz 5, 8093 Zürich, Switzerland.
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6
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Fernandez-Rodriguez MA, Martín-Molina A, Maldonado-Valderrama J. Microgels at interfaces, from mickering emulsions to flat interfaces and back. Adv Colloid Interface Sci 2021; 288:102350. [PMID: 33418470 DOI: 10.1016/j.cis.2020.102350] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 12/18/2020] [Accepted: 12/18/2020] [Indexed: 12/22/2022]
Abstract
In this review, we cover the topic of p(NIPAM) based microgels at interfaces, revisiting classical studies in light of the newest ones. In particular, we focus on their use as emulsifiers in the so-called mickering emulsions, i.e. Pickering emulsion stabilized by soft particles. Given the complexity of the experimental characterization and simulation of these soft particles at interfaces, the review is structured in progressive complexity levels, until we reach the highly interesting and promising responsiveness to stimuli of mickering emulsions. We start from the lowest level of complexity, the current understanding of the behavior of single microgels confined at a flat interface. Then, we discuss their collective behavior upon crowding, their responsiveness at interfaces, and their macroscopic properties as microgel films. Once we have the necessary characterization tools, we proceed to discuss the complex and convoluted picture of responsive mickering emulsions. The way is rough, with current controversial and contradicting studies, but it holds promising results as well. We state open questions worth of being tackled by the Soft Matter community, and we conclude that it is worth the trouble of continuing after the master theory of microgel interfacial activity, as it will pave the way to widely adopt responsive mickering emulsions as the worthy Pickering emulsion successors.
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Affiliation(s)
| | - Alberto Martín-Molina
- Department of Applied Physics, University of Granada, Campus de Fuentenueva s/n, 18071 Granada, Spain; Institute Carlos I for Theoretical and Computational Physics, University of Granada, Campus de Fuentenueva s/n, 18071 Granada, Spain
| | - Julia Maldonado-Valderrama
- Department of Applied Physics, University of Granada, Campus de Fuentenueva s/n, 18071 Granada, Spain; Excellence Unit "ModellingNature" (MNat), , University of Granada, Spain.
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7
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Fernandez-Rodriguez MA, Antonopoulou MN, Isa L. Near-zero surface pressure assembly of rectangular lattices of microgels at fluid interfaces for colloidal lithography. Soft Matter 2021; 17:335-340. [PMID: 33355590 DOI: 10.1039/d0sm01823f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Understanding and engineering the self-assembly of soft colloidal particles (microgels) at liquid-liquid interfaces is broadening their use in colloidal lithography. Here, we present a new route to assemble rectangular lattices of microgels at near zero surface pressure relying on the balance between attractive quadrupolar capillary interactions and steric repulsion among the particles at water/oil interfaces. These self-assembled rectangular lattices are obtained for a broad range of particles and, after deposition, can be used as lithography masks to obtain regular arrays of vertically aligned nanowires via wet and dry etching processes.
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Affiliation(s)
- Miguel Angel Fernandez-Rodriguez
- Laboratory of Surface and Interface Physics, Biocolloids and Fluid Physics group, Faculty of Sciences, University of Granada, Campus de Fuentenueva s/n, ES 18071 Granada, Spain. and Laboratory for Soft Materials and Interfaces, Swiss Federal Institute of Technology Zürich, Vladimir-Prelog-Weg 1-5/10, 8093 Zürich, Switzerland
| | - Maria-Nefeli Antonopoulou
- Laboratory for Soft Materials and Interfaces, Swiss Federal Institute of Technology Zürich, Vladimir-Prelog-Weg 1-5/10, 8093 Zürich, Switzerland
| | - Lucio Isa
- Laboratory for Soft Materials and Interfaces, Swiss Federal Institute of Technology Zürich, Vladimir-Prelog-Weg 1-5/10, 8093 Zürich, Switzerland
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8
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Sprenger AR, Fernandez-Rodriguez MA, Alvarez L, Isa L, Wittkowski R, Löwen H. Active Brownian Motion with Orientation-Dependent Motility: Theory and Experiments. Langmuir 2020; 36:7066-7073. [PMID: 31975603 DOI: 10.1021/acs.langmuir.9b03617] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Combining experiments on active colloids, whose propulsion velocity can be controlled via a feedback loop, and the theory of active Brownian motion, we explore the dynamics of an overdamped active particle with a motility that depends explicitly on the particle orientation. In this case, the active particle moves faster when oriented along one direction and slower when oriented along another, leading to anisotropic translational dynamics which is coupled to the particle's rotational diffusion. We propose a basic model of active Brownian motion for orientation-dependent motility. On the basis of this model, we obtain analytical results for the mean trajectories, averaged over the Brownian noise for various initial configurations, and for the mean-square displacements including their non-Gaussian behavior. The theoretical results are found to be in good agreement with the experimental data. Orientation-dependent motility is found to induce significant anisotropy in the particle displacement, mean-square displacement, and non-Gaussian parameter even in the long-time limit. Our findings establish a methodology for engineering complex anisotropic motilities of active Brownian particles, with a potential impact in the study of the swimming behavior of microorganisms subjected to anisotropic driving fields.
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Affiliation(s)
- Alexander R Sprenger
- Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, D-40225 Düsseldorf, Germany
| | | | - Laura Alvarez
- Laboratory for Soft Materials and Interfaces, Department of Materials, ETH Zürich, 8093 Zürich, Switzerland
| | - Lucio Isa
- Laboratory for Soft Materials and Interfaces, Department of Materials, ETH Zürich, 8093 Zürich, Switzerland
| | - Raphael Wittkowski
- Institut für Theoretische Physik, Center for Soft Nanoscience, Westfälische Wilhelms-Universität Münster, D-48149 Münster, Germany
| | - Hartmut Löwen
- Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, D-40225 Düsseldorf, Germany
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9
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Abstract
The confinement of colloidal particles at liquid interfaces offers many opportunities for materials design. Adsorption is driven by a reduction of the total free energy as the contact area between the two liquids is partially replaced by the particle. From an application point of view, particle-stabilized interfaces form emulsions and foams with superior stability. Liquid interfaces also effectively confine colloidal particles in two dimensions and therefore provide ideal model systems to fundamentally study particle interactions, dynamics, and self-assembly. With progress in the synthesis of nanomaterials, more and more complex and functional particles are available for such studies. In this Account, we focus on poly(N-isopropylacrylamide) nanogels and microgels. These are cross-linked polymeric particles that swell and soften by uptaking large amounts of water. The incorporated water can be partially expelled, causing a volume phase transition into a collapsed state when the temperature is increased above approximately 32 °C. Soft microgels adsorbed to liquid interfaces significantly deform under the influence of interfacial tension and assume cross sections exceeding their bulk dimensions. In particular, a pronounced corona forms around the microgel core, consisting of dangling chains at the microgel periphery. These polymer chains expand at the interface and strongly affect the interparticle interactions. The particle deformability therefore leads to a significantly more complex interfacial phase behavior that provides a rich playground to explore structure formation processes. We first discuss the characteristic "fried-egg" or core-corona morphology of individual microgels adsorbed to a liquid interface and comment on the dependence of this interfacial morphology on their physicochemical properties. We introduce different theoretical models to describe their interfacial morphology. In a second part, we introduce how ensembles of microgels interact and self-assemble at liquid interfaces. The core-corona morphology and the possibility to force these elements into overlap upon compression results in a complex phase behavior with a phase transition between microgels with extended and collapsed coronae. We discuss the influence of the internal particle architecture, also including core-shell microgels with rigid cores, on the phase behavior. Finally, we present new routes for the realization of more complex structures, resulting from multiple deposition protocols and from engineering the interaction potential of the individual particles.
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Affiliation(s)
- Marcel Rey
- Institute of Particle Technology (LFG), Friedrich-Alexander University Erlangen-Nürnberg, Cauerstrasse 4, 91058 Erlangen, Germany
- Interdisciplinary Center for Functional Particle Systems (FPS), Friedrich-Alexander University Erlangen-Nürnberg, Haberstrasse 9a, 91058 Erlangen, Germany
| | - Miguel Angel Fernandez-Rodriguez
- Laboratory for Soft Materials and Interfaces, Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, 8093 Zürich, Switzerland
| | - Matthias Karg
- Institut für Physikalische Chemie I: Kolloide und Nanooptik, Heinrich-Heine-Universität Düsseldorf, Universitätsstrasse 1, D-40225 Düsseldorf, Germany
| | - Lucio Isa
- Laboratory for Soft Materials and Interfaces, Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, 8093 Zürich, Switzerland
| | - Nicolas Vogel
- Institute of Particle Technology (LFG), Friedrich-Alexander University Erlangen-Nürnberg, Cauerstrasse 4, 91058 Erlangen, Germany
- Interdisciplinary Center for Functional Particle Systems (FPS), Friedrich-Alexander University Erlangen-Nürnberg, Haberstrasse 9a, 91058 Erlangen, Germany
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10
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Scotti A, Bochenek S, Brugnoni M, Fernandez-Rodriguez MA, Schulte MF, Houston JE, Gelissen APH, Potemkin II, Isa L, Richtering W. Exploring the colloid-to-polymer transition for ultra-low crosslinked microgels from three to two dimensions. Nat Commun 2019; 10:1418. [PMID: 30926786 PMCID: PMC6441029 DOI: 10.1038/s41467-019-09227-5] [Citation(s) in RCA: 76] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Accepted: 02/19/2019] [Indexed: 11/18/2022] Open
Abstract
Microgels are solvent-swollen nano- and microparticles that show prevalent colloidal-like behavior despite their polymeric nature. Here we study ultra-low crosslinked poly(N-isopropylacrylamide) microgels (ULC), which can behave like colloids or flexible polymers depending on dimensionality, compression or other external stimuli. Small-angle neutron scattering shows that the structure of the ULC microgels in bulk aqueous solution is characterized by a density profile that decays smoothly from the center to a fuzzy surface. Their phase behavior and rheological properties are those of soft colloids. However, when these microgels are confined at an oil-water interface, their behavior resembles that of flexible macromolecules. Once monolayers of ultra-low crosslinked microgels are compressed, deposited on solid substrate and studied with atomic-force microscopy, a concentration-dependent topography is observed. Depending on the compression, these microgels can behave as flexible polymers, covering the substrate with a uniform film, or as colloidal microgels leading to a monolayer of particles.
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Affiliation(s)
- A Scotti
- Institute of Physical Chemistry, RWTH Aachen University, 52056, Aachen, Germany.
| | - S Bochenek
- Institute of Physical Chemistry, RWTH Aachen University, 52056, Aachen, Germany
| | - M Brugnoni
- Institute of Physical Chemistry, RWTH Aachen University, 52056, Aachen, Germany
| | - M A Fernandez-Rodriguez
- Laboratory for Interfaces, Soft Matter and Assembly, Department of Materials, ETH Zurich, 8093, Zurich, Switzerland
| | - M F Schulte
- Institute of Physical Chemistry, RWTH Aachen University, 52056, Aachen, Germany
| | - J E Houston
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ) Forschungszentrum Jülich GmbH, 85748, Garching, Germany
- European Spallation Source ERIC, Box 176,, SE-221 00, Lund, Sweden
| | - A P H Gelissen
- Institute of Physical Chemistry, RWTH Aachen University, 52056, Aachen, Germany
| | - I I Potemkin
- Physics Department, Lomonosov Moscow State University, 119991, Moscow, Russian Federation
- DWI - Leibniz Institute for Interactive Materials, Aachen, 52056, Germany
- National Research South Ural State University, Chelyabinsk, 454080, Russian Federation
| | - L Isa
- Laboratory for Interfaces, Soft Matter and Assembly, Department of Materials, ETH Zurich, 8093, Zurich, Switzerland
| | - W Richtering
- Institute of Physical Chemistry, RWTH Aachen University, 52056, Aachen, Germany.
- JARA-SOFT, 52056, Aachen, Germany.
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11
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Fernandez-Rodriguez MA, Binks BP, Rodriguez-Valverde MA, Cabrerizo-Vilchez MA, Hidalgo-Alvarez R. Particles adsorbed at various non-aqueous liquid-liquid interfaces. Adv Colloid Interface Sci 2017; 247:208-222. [PMID: 28219622 DOI: 10.1016/j.cis.2017.02.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Accepted: 02/05/2017] [Indexed: 02/02/2023]
Abstract
Particles adsorbed at liquid interfaces are commonly used to stabilise water-oil Pickering emulsions and water-air foams. The fundamental understanding of the physics of particles adsorbed at water-air and water-oil interfaces is improving significantly due to novel techniques that enable the measurement of the contact angle of individual particles at a given interface. The case of non-aqueous interfaces and emulsions is less studied in the literature. Non-aqueous liquid-liquid interfaces in which water is replaced by other polar solvents have properties similar to those of water-oil interfaces. Nanocomposites of non-aqueous immiscible polymer blends containing inorganic particles at the interface are of great interest industrially and consequently more work has been devoted to them. By contrast, the behaviour of particles adsorbed at oil-oil interfaces in which both oils are immiscible and of low dielectric constant (ε<3) is scarcely studied. Hydrophobic particles are required to stabilise these oil-oil emulsions due to their irreversible adsorption, high interfacial activity and elastic shell behaviour.
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Affiliation(s)
- Miguel Angel Fernandez-Rodriguez
- Biocolloid and Fluid Physics Group, Applied Physics Department, Faculty of Sciences, University of Granada, 18071-E Granada, Spain.
| | - Bernard P Binks
- School of Mathematics and Physical Sciences, University of Hull, Hull HU6 7RX, UK
| | - Miguel Angel Rodriguez-Valverde
- Biocolloid and Fluid Physics Group, Applied Physics Department, Faculty of Sciences, University of Granada, 18071-E Granada, Spain
| | - Miguel Angel Cabrerizo-Vilchez
- Biocolloid and Fluid Physics Group, Applied Physics Department, Faculty of Sciences, University of Granada, 18071-E Granada, Spain
| | - Roque Hidalgo-Alvarez
- Biocolloid and Fluid Physics Group, Applied Physics Department, Faculty of Sciences, University of Granada, 18071-E Granada, Spain
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12
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Fernandez-Rodriguez MA, Rodriguez-Valverde MA, Cabrerizo-Vilchez MA, Hidalgo-Alvarez R. Surface activity of Janus particles adsorbed at fluid-fluid interfaces: Theoretical and experimental aspects. Adv Colloid Interface Sci 2016; 233:240-254. [PMID: 26094083 DOI: 10.1016/j.cis.2015.06.002] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Revised: 06/04/2015] [Accepted: 06/04/2015] [Indexed: 10/23/2022]
Abstract
Since de Gennes coined in 1992 the term Janus particle (JP), there has been a continued effort to develop this field. The purpose of this review is to present the most relevant theoretical and experimental results obtained so far on the surface activity of amphiphilic JPs at fluid interfaces. The surface activity of JPs at fluid-fluid interfaces can be experimentally determined using two different methods: the classical Langmuir balance or the pendant drop tensiometry. The second method requires much less amount of sample than the first one, but it has also some experimental limitations. In all cases collected here the JPs exhibited a higher surface or interfacial activity than the corresponding homogeneous particles. This reveals the significant advantage of JPs for the stabilization of emulsions and foams.
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13
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Fernandez-Rodriguez MA, Chen L, Deming CP, Rodriguez-Valverde MA, Chen S, Cabrerizo-Vilchez MA, Hidalgo-Alvarez R. A simple strategy to improve the interfacial activity of true Janus gold nanoparticles: a shorter hydrophilic capping ligand. Soft Matter 2016; 12:31-34. [PMID: 26451801 DOI: 10.1039/c5sm01908g] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Janus gold nanoparticles (JPs) of ∼4 nm-diameter half functionalized with 1-hexanethiol as a hydrophobic capping ligand exhibit significantly higher interfacial activity, reproducibility and rheological response when the other half is functionalized with 1,2-mercaptopropanediol (JPs-MPD) than with 2-(2-mercaptoethoxy)ethanol (JPs-MEE), both acting as hydrophilic capping ligands. The interfacial pressure measured by pendant drop tensiometry reaches 50 mN m(-1) and 35 mN m(-1) for the JPs-MPD at the water/air and water/decane interface, respectively. At the same area per particle, the JPs-MEE reveal significantly lower interfacial pressure: 15 mN m(-1) and 5 mN m(-1) at the water/air and water/decane interface, respectively. Interfacial dilatational rheology measurements also show an elastic shell behaviour at higher compression states for JPs-MPD while the JPs-MEE present near-zero elasticity. The enhanced interfacial activity of JPs-MPD is explained in terms of chemical and hydration differences between the MPD and MEE ligands, where MPD has a shorter hydrocarbon chain and twice as many hydroxyl terminal groups as MEE.
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Affiliation(s)
| | - Limei Chen
- Department of Chemistry and Biochemistry, University of California, 1156 High Street, Santa Cruz, CA 95064, USA
| | - Christopher P Deming
- Department of Chemistry and Biochemistry, University of California, 1156 High Street, Santa Cruz, CA 95064, USA
| | | | - Shaowei Chen
- Department of Chemistry and Biochemistry, University of California, 1156 High Street, Santa Cruz, CA 95064, USA
| | - Miguel Angel Cabrerizo-Vilchez
- Biocolloid and Fluid Physics Group, Applied Physics Department, Faculty of Sciences, University of Granada, Granada, Spain.
| | - Roque Hidalgo-Alvarez
- Biocolloid and Fluid Physics Group, Applied Physics Department, Faculty of Sciences, University of Granada, Granada, Spain.
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Fernandez-Rodriguez MA, Song Y, Rodríguez-Valverde MÁ, Chen S, Cabrerizo-Vilchez MA, Hidalgo-Alvarez R. Comparison of the interfacial activity between homogeneous and Janus gold nanoparticles by pendant drop tensiometry. Langmuir 2014; 30:1799-804. [PMID: 24490655 DOI: 10.1021/la404194e] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The interfacial activity of 3.5 nm homogeneous (HPs) and amphiphilic Janus gold nanoparticles (JPs) was characterized by pendant drop tensiometry for water/air and water/decane interfaces. This technique requires a smaller quantity of nanoparticles than the traditional Langmuir balance technique. The direct deposition at the interface of the nanoparticles dispersed in a spreading solvent also requires smaller quantities of sample than does adsorption from the bulk. From the growing and shrinking of the pendant drops, the interfacial activity of the nanoparticles can be evaluated and compared within a wide range of area per particle. In this work, the JPs exhibited a higher interfacial activity than did the HPs in all cases. A hard disk model fits the piecewise compression isotherm of the HPs, yet this model underestimates the interactions between the JPs adsorbed at the interface.
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Affiliation(s)
- Miguel Angel Fernandez-Rodriguez
- Biocolloid and Fluid Physics Group, Applied Physics Department, Faculty of Sciences, University of Granada , 18071 Granada, Spain
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15
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Alvarez-Viejo M, Menendez-Menendez Y, Blanco-Gelaz MA, Ferrero-Gutierrez A, Fernandez-Rodriguez MA, Gala J, Otero-Hernandez J. Quantifying mesenchymal stem cells in the mononuclear cell fraction of bone marrow samples obtained for cell therapy. Transplant Proc 2013; 45:434-9. [PMID: 23375334 DOI: 10.1016/j.transproceed.2012.05.091] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Revised: 12/14/2011] [Accepted: 05/04/2012] [Indexed: 12/15/2022]
Abstract
AIMS The use of bone marrow mononuclear cells (BMMNCs) as a source of mesenchymal stem cells (MSCs) for therapy has recently attracted the attention of researchers because BMMNCs can be easily obtained and do not require in vitro expansion before their use. This study was designed to quantify the MSC population in bone marrow (BM) samples obtained for cell therapy using flow cytometry to detect the CD271 antigen. MATERIAL AND METHODS Autologous BM was obtained by posterior superior iliac crest aspiration under topical anesthesia. Mononuclear cells isolated from the BM aspirate on a Ficoll density gradient were used to treat patients with pressure ulcer (n = 13) bone nonunions (n = 3) or diabetic foot ulcers (n = 5). RESULTS Our flow cytometry data revealed a low percentage as well as a high variability among patients of CD271(+)CD45(-) cells (range, 0.0017 to 0.0201%). All cultured MSC adhered to plastic dishes showing a capacity to differentiate into adipogenic and osteogenic lineages. CONCLUSIONS Our findings suggested that the success of cell therapy was independent of the number of MSCs present in the BM aspirate used for autologous cell therapy.
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Affiliation(s)
- M Alvarez-Viejo
- Transplant and Cell Therapy Unit, Hospital Universitario Central de Asturias, Oviedo, Spain.
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