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Article ; Online: Influence of Surfactant Concentration on Spontaneous Emulsification Kinetics.

Toor, Ritu / Denoyel, Renaud / Liggieri, Libero / Schmitt, Murielle / Antoni, Mickaël

Langmuir : the ACS journal of surfaces and colloids

2022 Volume 38, Issue 38, Page(s) 11521–11528

Abstract: The kinetics of spontaneous emulsification is investigated on aqueous pendant drops in paraffin oil. Optical microscopy in transmission mode is used for high-spatial-resolution image recording. The influence of a lipophilic surfactant (Span 80) and two ... ...

Abstract	The kinetics of spontaneous emulsification is investigated on aqueous pendant drops in paraffin oil. Optical microscopy in transmission mode is used for high-spatial-resolution image recording. The influence of a lipophilic surfactant (Span 80) and two water-soluble surfactants (CTAB and SDS) is investigated. As time runs, the drop interface turns opaque due to the formation of microstructures associated with spontaneous emulsification. The time evolution of this phenomenon is shown to depend upon temperature and surfactant concentration, which leads to an overall shrinkage due to gradual water uptake and transport into paraffin oil. Spontaneous emulsification kinetics depends upon the chemical composition. Higher concentrations of Span 80 and CTAB (resp. SDS) are shown to promote (resp. hinder) water transport. This work provides new insights into the understanding of spontaneous emulsification when combining the properties of non-ionic and ionic surfactants.
Language	English
Publishing date	2022-09-12
Publishing country	United States
Document type	Journal Article
ZDB-ID	2005937-1
ISSN	1520-5827 ; 0743-7463
ISSN (online)	1520-5827
ISSN	0743-7463
DOI	10.1021/acs.langmuir.1c03443
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article: Influence of Surfactant Concentration on Spontaneous Emulsification Kinetics

Toor, Ritu / Denoyel, Renaud / Liggieri, Libero / Schmitt, Murielle / Antoni, Mickaël

Langmuir. 2022 Sept. 12, v. 38, no. 38

2022

Abstract	The kinetics of spontaneous emulsification is investigated on aqueous pendant drops in paraffin oil. Optical microscopy in transmission mode is used for high-spatial-resolution image recording. The influence of a lipophilic surfactant (Span 80) and two water-soluble surfactants (CTAB and SDS) is investigated. As time runs, the drop interface turns opaque due to the formation of microstructures associated with spontaneous emulsification. The time evolution of this phenomenon is shown to depend upon temperature and surfactant concentration, which leads to an overall shrinkage due to gradual water uptake and transport into paraffin oil. Spontaneous emulsification kinetics depends upon the chemical composition. Higher concentrations of Span 80 and CTAB (resp. SDS) are shown to promote (resp. hinder) water transport. This work provides new insights into the understanding of spontaneous emulsification when combining the properties of non-ionic and ionic surfactants.
Keywords	chemical composition ; emulsifying ; light microscopy ; lipophilicity ; oils ; shrinkage ; surfactants ; temperature ; water solubility ; water uptake
Language	English
Dates of publication	2022-0912
Size	p. 11521-11528.
Publishing place	American Chemical Society
Document type	Article
ZDB-ID	2005937-1
ISSN	1520-5827 ; 0743-7463
ISSN (online)	1520-5827
ISSN	0743-7463
DOI	10.1021/acs.langmuir.1c03443
Database	NAL-Catalogue (AGRICOLA)

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Article: Enzymatic cascade reaction in simple-coacervates

Toor, Ritu / Hourdin, Lysandre / Shanmugathasan, Sharvina / Lefrançois, Pauline / Arbault, Stéphane / Lapeyre, Véronique / Bouffier, Laurent / Douliez, Jean-Paul / Ravaine, Valérie / Perro, Adeline

Journal of colloid and interface science. 2023 Jan., v. 629

2023

Abstract: The design of enzymatic droplet-sized reactors constitutes an important challenge with many potential applications such as medical diagnostics, water purification, bioengineering, or food industry. Coacervates, which are all-aqueous droplets, afford a ... ...

Abstract	The design of enzymatic droplet-sized reactors constitutes an important challenge with many potential applications such as medical diagnostics, water purification, bioengineering, or food industry. Coacervates, which are all-aqueous droplets, afford a simple model for the investigation of enzymatic cascade reaction since the reactions occur in all-aqueous media, which preserve the enzymes integrity. However, the question relative to how the sequestration and the proximity of enzymes within the coacervates might affect their activity remains open. Herein, we report the construction of enzymatic reactors exploiting the simple coacervation of ampholyte polymer chains, stabilized with agar. We demonstrate that these coacervates have the ability to sequester enzymes such as glucose oxidase and catalase and preserve their catalytic activity. The study is carried out by analyzing the color variation induced by the reduction of resazurin. Usually, phenoxazine molecules acting as electron acceptors are used to characterize glucose oxidase activity. Resazurin (pink) undergoes a first reduction to resorufin (salmon) and then to dihydroresorufin (transparent) in presence of glucose oxidase and glucose. We have observed that resorufin is partially regenerated in the presence of catalase, which demonstrates the enzymatic cascade reaction. Studying this enzymatic cascade reaction within coacervates as reactors provide new insights into the role of the proximity, confinement towards enzymatic activity.
Keywords	agar ; catalase ; catalytic activity ; color ; diagnostic techniques ; enzyme activity ; food industry ; glucose ; glucose oxidase ; models ; polymers ; salmon ; water purification
Language	English
Dates of publication	2023-01
Size	p. 46-54.
Publishing place	Elsevier Inc.
Document type	Article
ZDB-ID	241597-5
ISSN	1095-7103 ; 0021-9797
ISSN (online)	1095-7103
ISSN	0021-9797
DOI	10.1016/j.jcis.2022.09.019
Database	NAL-Catalogue (AGRICOLA)

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Article ; Online: Responsive microgels-based colloidosomes constructed from all-aqueous pH-switchable coacervate droplets.

Toor, Ritu / Neujahr Copstein, Amanda / Trébuchet, Claire / Goudeau, Bertrand / Garrigue, Patrick / Lapeyre, Véronique / Perro, Adeline / Ravaine, Valérie

Journal of colloid and interface science

2022 Volume 630, Issue Pt B, Page(s) 66–75

Abstract: Hypothesis: Colloidosomes made of stimuli-responsive microgels offer the opportunity to design polymeric capsules with a hierarchical and tunable pore distribution. Coacervates stabilized by a microgel monolayer represent a unique strategy to build ... ...

Abstract	Hypothesis: Colloidosomes made of stimuli-responsive microgels offer the opportunity to design polymeric capsules with a hierarchical and tunable pore distribution. Coacervates stabilized by a microgel monolayer represent a unique strategy to build colloidosomes from all-aqueous emulsion drops, while exploiting the sequestration and dissolution properties of the coacervates. Experiments: Methacrylated poly(N-isopropylacrylamide) (pNIPAM) microgels are used to stabilize coacervates made of an ampholyte polymer at a pH close to its isoelectric point. They are further cross-linked under UV-irradiation. The resulting assemblies are studied by means of confocal microscopy. Their permeability towards dextrans and nanoparticles is studied before and after dissolution of the coacervate. Findings: PNIPAM microgels are found to stabilize the coacervates by adsorbing at their surface. Inter cross-linking the microgels results in the formation of an elastic colloidosome that persists after the coacervate dissolution and withstands surface deformations up to about 200%. The coacervate is exploited as a sequestrating core to entrap a water-soluble payload, which can be further released upon coacervate dissolution, while the membrane exhibits a size-selecting permeability. The membrane properties can also be switched by the volume phase transition of the microgels. Coacervate-embedded colloidosomes open new perspectives in the area of encapsulation/extraction and controlled transport of water-soluble/dispersed species.
MeSH term(s)	Microgels ; Water/chemistry ; Emulsions/chemistry ; Gels/chemistry ; Polymers/chemistry ; Hydrogen-Ion Concentration
Chemical Substances	Microgels ; Water (059QF0KO0R) ; Emulsions ; Gels ; Polymers
Language	English
Publishing date	2022-10-19
Publishing country	United States
Document type	Journal Article
ZDB-ID	241597-5
ISSN	1095-7103 ; 0021-9797
ISSN (online)	1095-7103
ISSN	0021-9797
DOI	10.1016/j.jcis.2022.10.068
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Z 71/707: Show issues

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Article ; Online: Spontaneous Microstructure Formation at Water/Paraffin Oil Interfaces.

Schmitt, Murielle / Toor, Ritu / Denoyel, Renaud / Antoni, Mickaël

Langmuir : the ACS journal of surfaces and colloids

2017 Volume 33, Issue 49, Page(s) 14011–14019

Abstract: An experimental investigation of spontaneous emulsification is proposed with a water drop pendant in a paraffin oil (PO) solution loaded with a surfactant (SPAN80). Optical microscopy in a transmission mode is employed for high-spatial-resolution image ... ...

Abstract	An experimental investigation of spontaneous emulsification is proposed with a water drop pendant in a paraffin oil (PO) solution loaded with a surfactant (SPAN80). Optical microscopy in a transmission mode is employed for high-spatial-resolution image recording. The kinetics of spontaneous emulsification is studied. It is shown to generate a darkening of the drops because of interface modification with a characteristic time that depends upon the SPAN80 concentration. For low concentrations, spontaneous emulsification is slow and produces micrometer-sized droplets, whereas for large concentrations, it is fast and bush-like microstructures are observed. These microstructures increase in size and progressively invade the complete water/PO interfaces, detach, and finally migrate into the PO phase. This transport phenomenon withdraws water from the drops and leads to a gradual shrinking of their volume. At the end of this process, they appear as deformed objects surrounded by a loose membrane.
Language	English
Publishing date	2017--12
Publishing country	United States
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	2005937-1
ISSN	1520-5827 ; 0743-7463
ISSN (online)	1520-5827
ISSN	0743-7463
DOI	10.1021/acs.langmuir.7b02549
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article ; Online: Impact of Multimeric Ferrocene-containing Cyclodecapeptide Scaffold on Host-Guest Interactions at a β-Cyclodextrin Covered Surface.

Sanchez Perez, Enrique / Toor, Ritu / Bruyat, Pierrick / Cepeda, Céline / Degardin, Mélissa / Dejeu, Jérôme / Boturyn, Didier / Coche-Guérente, Liliane

Chemphyschem : a European journal of chemical physics and physical chemistry

2021 Volume 22, Issue 21, Page(s) 2231–2239

Abstract: Among non-covalent bonds, the host-guest interaction is an attractive way to attach biomolecules to solid surfaces since the binding strength can be tuned by the nature of host and guest partners or through the valency of the interaction. For that ... ...

Abstract	Among non-covalent bonds, the host-guest interaction is an attractive way to attach biomolecules to solid surfaces since the binding strength can be tuned by the nature of host and guest partners or through the valency of the interaction. For that purpose, we synthesized cyclodecapeptide scaffolds exhibiting in a spatially controlled manner two independent domains enabling the multimeric presentation of guest molecules on one face and the other face enabling the potential grafting of a biomolecule of interest. In this work, we were interested in the β-cyclodextrin/ferrocene inclusion complex formed on β-CD monolayers functionalized surfaces. By using surface sensitive techniques such as quartz crystal microbalance and surface plasmon resonance, we quantified the influence of the guest valency on the stability of the inclusion complexes. The results show a drastic enhancement of the affinity with the gradual increase of guest valency. Considering that the sequential binding events are equal and independent, we applied the multivalent model developed by the Huskens group to extract intrinsic binding constants and an effective concentration of host.
MeSH term(s)	Metallocenes/chemistry ; Molecular Structure ; Peptides, Cyclic/chemical synthesis ; Peptides, Cyclic/chemistry ; Surface Properties ; beta-Cyclodextrins/chemistry
Chemical Substances	Metallocenes ; Peptides, Cyclic ; beta-Cyclodextrins
Language	English
Publishing date	2021-08-23
Publishing country	Germany
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	2025223-7
ISSN	1439-7641 ; 1439-4235
ISSN (online)	1439-7641
ISSN	1439-4235
DOI	10.1002/cphc.202100469
Database	MEDical Literature Analysis and Retrieval System OnLINE

2022 Volume 629, Issue Pt B, Page(s) 46–54

Abstract	The design of enzymatic droplet-sized reactors constitutes an important challenge with many potential applications such as medical diagnostics, water purification, bioengineering, or food industry. Coacervates, which are all-aqueous droplets, afford a simple model for the investigation of enzymatic cascade reaction since the reactions occur in all-aqueous media, which preserve the enzymes integrity. However, the question relative to how the sequestration and the proximity of enzymes within the coacervates might affect their activity remains open. Herein, we report the construction of enzymatic reactors exploiting the simple coacervation of ampholyte polymer chains, stabilized with agar. We demonstrate that these coacervates have the ability to sequester enzymes such as glucose oxidase and catalase and preserve their catalytic activity. The study is carried out by analyzing the color variation induced by the reduction of resazurin. Usually, phenoxazine molecules acting as electron acceptors are used to characterize glucose oxidase activity. Resazurin (pink) undergoes a first reduction to resorufin (salmon) and then to dihydroresorufin (transparent) in presence of glucose oxidase and glucose. We have observed that resorufin is partially regenerated in the presence of catalase, which demonstrates the enzymatic cascade reaction. Studying this enzymatic cascade reaction within coacervates as reactors provide new insights into the role of the proximity, confinement towards enzymatic activity.
MeSH term(s)	Glucose Oxidase ; Catalase ; Water
Chemical Substances	Glucose Oxidase (EC 1.1.3.4) ; Catalase (EC 1.11.1.6) ; Water (059QF0KO0R)
Language	English
Publishing date	2022-09-08
Publishing country	United States
Document type	Journal Article
ZDB-ID	241597-5
ISSN	1095-7103 ; 0021-9797
ISSN (online)	1095-7103
ISSN	0021-9797
DOI	10.1016/j.jcis.2022.09.019
Database	MEDical Literature Analysis and Retrieval System OnLINE

In stock of ZB MED Bonn / Germany

Z 71/707: Show issues

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Article: Spontaneous Microstructure Formation at Water/Paraffin Oil Interfaces

Schmitt, Murielle / Toor Ritu / Denoyel Renaud / Antoni MickaeÌl

Langmuir. 2017 Dec. 12, v. 33, no. 49

2017

Abstract	An experimental investigation of spontaneous emulsification is proposed with a water drop pendant in a paraffin oil (PO) solution loaded with a surfactant (SPAN80). Optical microscopy in a transmission mode is employed for high-spatial-resolution image recording. The kinetics of spontaneous emulsification is studied. It is shown to generate a darkening of the drops because of interface modification with a characteristic time that depends upon the SPAN80 concentration. For low concentrations, spontaneous emulsification is slow and produces micrometer-sized droplets, whereas for large concentrations, it is fast and bush-like microstructures are observed. These microstructures increase in size and progressively invade the complete water/PO interfaces, detach, and finally migrate into the PO phase. This transport phenomenon withdraws water from the drops and leads to a gradual shrinking of their volume. At the end of this process, they appear as deformed objects surrounded by a loose membrane.
Keywords	droplets ; emulsifying ; light microscopy ; microstructure ; oils ; surfactants
Language	English
Dates of publication	2017-1212
Size	p. 14011-14019.
Publishing place	American Chemical Society
Document type	Article
ZDB-ID	2005937-1
ISSN	1520-5827 ; 0743-7463
ISSN (online)	1520-5827
ISSN	0743-7463
DOI	10.1021%2Facs.langmuir.7b02549
Database	NAL-Catalogue (AGRICOLA)

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