scholarly journals BslA-stabilized emulsion droplets with designed microstructure

2017 ◽  
Vol 7 (4) ◽  
pp. 20160124 ◽  
Author(s):  
Keith M. Bromley ◽  
Cait E. MacPhee
Keyword(s):  
Structural Integrity ◽  
Melting Process ◽  
Continuous Phase ◽  
Central Component ◽  
Emulsion Droplet ◽  
Emulsion Droplets ◽  
Elastic Film ◽  
Air Water Interface ◽  
Droplet Morphology ◽  
Spherical Droplets

Emulsions are a central component of many modern formulations in food, pharmaceuticals, agrichemicals and personal care products. The droplets in these formulations are limited to being spherical as a consequence of the interfacial tension between the dispersed phase and continuous phase. The ability to control emulsion droplet morphology and stabilize non-spherical droplets would enable the modification of emulsion properties such as stability, substrate binding, delivery rate and rheology. One way of controlling droplet microstructure is to apply an elastic film around the droplet to prevent it from relaxing into a sphere. We have previously shown that BslA, an interfacial protein produced by the bacterial genus Bacillus , forms an elastic film when exposed to an oil- or air–water interface. Here, we highlight BslA's ability to stabilize anisotropic emulsion droplets. First, we show that BslA is capable of arresting dynamic emulsification processes leading to emulsions with variable morphologies depending on the conditions and emulsification technique applied. We then show that frozen emulsion droplets can be manipulated to induce partial coalescence. The structure of the partially coalesced droplets is retained after melting, but only when there is sufficient free BslA in the continuous phase. That the fidelity of replication can be tuned by adjusting the amount of free BslA in solution suggests that freezing BslA-stabilized droplets disrupts the BslA film. Finally, we use BslA's ability to preserve emulsion droplet structural integrity throughout the melting process to design emulsion droplets with a chosen shape and size.

Crystal Comets: Dewetting During Emulsion Droplet Crystallization

2005 ◽  
Vol 58 (9) ◽  
pp. 655 ◽  
Author(s):  
Patrick T. Spicer ◽  
Richard W. Hartel
Keyword(s):  
Cooling Rate ◽  
Continuous Phase ◽  
Surfactant Adsorption ◽  
Water Interface ◽  
Crystal Shape ◽  
Emulsion Droplet ◽  
Comet Tail ◽  
Oil Emulsion ◽  
Emulsion Droplets ◽  
Oil Water

Liquid oil emulsion droplets can violently dewet their own solid crystals during crystallization as a result of surfactant adsorption. The crystal shape formed is a function of the relative rates of dewetting and crystallization as controlled by surfactant adsorption, cooling rate, and lipid purity. For negligible dewetting rates, crystals nucleate and grow within the droplet. At similar crystallization and dewetting rates, the droplet is propelled around the continuous phase on a crystalline ‘comet tail’ much larger than the original droplet. Rapid dewetting causes the ejection of small discrete crystals across the droplet’s oil–water interface.

scholarly journals Bi-phase emulsion droplets as dynamic fluid optical systems

2019 ◽  
Vol 215 ◽  
pp. 13003
Author(s):  
Sara Nagelberg ◽  
Amy Goodling ◽  
Kaushikaram Subramanian ◽  
George Barbastathis ◽  
Moritz Kreysing ◽  
...  
Keyword(s):  
Critical Role ◽  
Optical Systems ◽  
Emulsion Droplet ◽  
Optical Elements ◽  
Optical Components ◽  
Micro Scale ◽  
Emulsion Droplets ◽  
Spectral Separation ◽  
Optical Behavior ◽  
Scatter Light

Micro-scale optical components play a critical role in many applications, in particular when these components are capable of dynamically responding to different stimuli with a controlled variation of their optical behavior. Here, we discuss the potential of micro-scale bi-phase emulsion droplets as a material platform for dynamic fluid optical components. Such droplets act as liquid compound micro-lenses with dynamically tunable focal lengths. They can be reconfigured to focus or scatter light and form images. In addition, we discuss how these droplets can be used to create iridescent structural color with large angular spectral separation. Experimental demonstrations of the emulsion droplet optics are complemented by theoretical analysis and wave-optical modelling. Finally, we provide evidence of the droplets utility as fluidic optical elements in potential application scenarios.

Mineralization of water-in-oil emulsion droplets

2004 ◽  
Vol 847 ◽  
Author(s):  
Giulia Fornasieri ◽  
Stéphane Badaire ◽  
Rénal Vasco Backov ◽  
Philippe Poulin ◽  
Cécile Zakri ◽  
...  
Keyword(s):  
Continuous Phase ◽  
Water Soluble ◽  
Oil Emulsion ◽  
Emulsion Droplets ◽  
Emulsion Systems ◽  
Oil Water ◽  
Silica Precursor ◽  
Concentration Threshold ◽  
Water In Oil Emulsion ◽  
Soluble Surfactant

Using reverse emulsion systems, we were able to trigger mineralization confined at an oil-water interface. In this process, the alcoxide silica precursor is dissolved in the oil continuous phase of the emulsion and diffuses through the bulk to the interface where it starts to hydrolyze and condense as soon as a certain concentration threshold is attained. The process takes place only in the presence of a water soluble surfactant inside the droplet. This surfactant leads to the presence of a controlled mesoporosity inside the silica shells. The obtained objects could be used in different encapsulation applications.

scholarly journals The Effect of pH and High-Pressure Homogenization on Droplet Size

2017 ◽  
Vol 2 (4) ◽  
pp. 110-122
Author(s):  
Ah Pis Yong ◽  
Md. Aminul Islam ◽  
Nurul Hasan
Keyword(s):  
High Pressure ◽  
Light Scattering ◽  
Droplet Size ◽  
Skim Milk ◽  
Egg Yolk ◽  
Continuous Phase ◽  
High Pressure Homogenization ◽  
Emulsion Droplets ◽  
Droplet Sizes ◽  
Basil Oil

The aims of this study are to revisit the effect of high pressure on homogenization and the influence of pH on the emulsion droplet sizes. The high-pressure homogenization (HPH) involves two stages of processing, where the first stage involves in blending the coarse emulsion by a blender, and the second stage requires disruption of the coarse emulsion into smaller droplets by a high-pressure homogenizer. The pressure range in this review is in between 10-500 MPa. The homogenised droplet sizes can be reduced by increasing the homogenization recirculation, and there is a threshold point beyond that by applying pressure only, the size cannot be further reduced. Normally, homogenised emulsions are classified by their degree of kinetic stability. Dispersed phase present in the form of droplets while continuous phase also known as suspended droplets. With a proper homogenization recirculation and pressure, a more kinetically stable emulsion can be produced. The side effects of increasing homogenization pressure are that it can cause overprocessing of the emulsion droplets where the droplet sizes become larger rather than the expected smaller size. This can cause kinetic instability in the emulsion. The droplet size is usually measured by dynamic light scattering or by laser light scattering technique. The type of samples used in this reviews are such as chocolate and vanilla based powders; mean droplet sizes samples; basil oil; tomato; lupin protein; oil; skim milk, soymilk; coconut milk; tomato homogenate; corn; egg-yolk, rapeseed and sunflower; Poly(4-vinylpyridine)/silica; and Complex 1 until complex 4 approaches from author case study. A relationship is developed between emulsion size and pH. Results clearly show that lower pH offers smaller droplet of emulsion and the opposite occurs when the pH is increased.

Shape control of nanostructured cone-shaped particles by tuning the blend morphology of A-b-B diblock copolymers and C-type copolymers within emulsion droplets

2019 ◽  
Vol 10 (19) ◽  
pp. 2415-2423 ◽  
Author(s):  
Eun Ji Kim ◽  
Jae Man Shin ◽  
YongJoo Kim ◽  
Kang Hee Ku ◽  
Hongseok Yun ◽  
...  
Keyword(s):  
Block Copolymers ◽  
Particle Shape ◽  
Shape Control ◽  
Diblock Copolymers ◽  
Emulsion Droplet ◽  
Emulsion Droplets ◽  
Blend Morphology ◽  
Engineering Strategy

An approach to blend AB-type block copolymers and C-type copolymers within the emulsion droplet is an efficient particle shape-engineering strategy.

Promoting Network Formation in Nanorod-filled Binary Blends

2012 ◽  
Vol 1411 ◽  
Author(s):  
Li-Tang Yan ◽  
Egor Maresov ◽  
Ryan C. Hayward ◽  
Todd Emrick ◽  
Thomas P. Russell ◽  
...  
Keyword(s):  
Network Formation ◽  
Early Stage ◽  
Continuous Phase ◽  
Domain Growth ◽  
Repulsive Interaction ◽  
Binary Blends ◽  
Growth Regime ◽  
The Matrix ◽  
Effective Attraction ◽  
Droplet Morphology

ABSTRACTUsing a hybrid computational approach, we introduce A-like nanorods into a phaseseparating AB blend, which has 45/55 composition. In the absence of the rods, the minority A phase forms droplets in the matrix of B. With the addition of N = 670 rods that interact solely through a short range repulsive interaction (mimicking the steric stabilization provided by a coating of A ligands), the mixture retains this droplet morphology. When, however, we add an effective attraction between the sterically stabilized rods, the nanoparticles form extensive networks in the A phase, which can form a continuous phase. In addition to altering the morphology of the mixture, the attractive interaction influences the rate of domain growth. In particular, at early times, the mutually attractive rods increase the growth rate of the domains in the early stage. At late times, the domain growth crosses over to a slow growth regime. Our findings demonstrate that the morphology and coarsening of a rod-filled blend can be controlled by varying the rod-rod interaction and hence, provides guidelines for tailoring the electrical and mechanical properties of the nanocomposites.

Monitoring Entering and Spreading of Emulsion Droplets at an Expanding Air/Water Interface: A Novel Technique

2002 ◽  
Vol 247 (1) ◽  
pp. 125-131 ◽  
Author(s):  
N.E. Hotrum ◽  
T. van Vliet ◽  
M.A. Cohen Stuart ◽  
G.A. van Aken
Keyword(s):  
Water Interface ◽  
Novel Technique ◽  
Emulsion Droplets ◽  
Air Water Interface

scholarly journals The antiviral sirtuin 3 bridges protein acetylation to mitochondrial integrity and metabolism during human cytomegalovirus infection

2021 ◽  
Vol 17 (4) ◽  
pp. e1009506
Author(s):  
Xinlei Sheng ◽  
Ileana M. Cristea
Keyword(s):  
Human Cytomegalovirus ◽  
Structural Integrity ◽  
Hcmv Infection ◽  
Temporal Dynamics ◽  
Virus Production ◽  
Central Component ◽  
Mitochondrial Morphology ◽  
Protein Levels ◽  
Acetylation Status ◽  
And Function

Regulation of mitochondrial structure and function is a central component of infection with viruses, including human cytomegalovirus (HCMV), as a virus means to modulate cellular metabolism and immune responses. Here, we link the activity of the mitochondrial deacetylase SIRT3 and global mitochondrial acetylation status to host antiviral responses via regulation of both mitochondrial structural integrity and metabolism during HCMV infection. We establish that SIRT3 deacetylase activity is necessary for suppressing virus production, and that SIRT3 maintains mitochondrial pH and membrane potential during infection. By defining the temporal dynamics of SIRT3-substrate interactions during infection, and overlaying acetylome and proteome information, we find altered SIRT3 associations with the mitochondrial fusion factor OPA1 and acetyl-CoA acyltransferase 2 (ACAA2), concomitant with changes in their acetylation levels. Using mutagenesis, microscopy, and virology assays, we determine OPA1 regulates mitochondrial morphology of infected cells and inhibits HCMV production. OPA1 acetylation status modulates these functions, and we establish K834 as a site regulated by SIRT3. Control of SIRT3 protein levels or enzymatic activity is sufficient for regulating mitochondrial filamentous structure. Lastly, we establish a virus restriction function for ACAA2, an enzyme involved in fatty acid beta-oxidation. Altogether, we highlight SIRT3 activity as a regulatory hub for mitochondrial acetylation and morphology during HCMV infection and point to global acetylation as a reflection of mitochondrial health.

scholarly journals Microfluidic on-chip Production of Alginate Hydrogels Using Double Co-flow Geometry

2021 ◽  
Author(s):  
Amirmohammad Sattari ◽  
Sajad Janfaza ◽  
Mohsen Mashhadi Keshtiban ◽  
Nishat Tasnim ◽  
Pedram Hanafizadeh ◽  
...  
Keyword(s):  
Microfluidic Device ◽  
Precursor Solution ◽  
Average Diameter ◽  
Continuous Phase ◽  
Solution Viscosity ◽  
Flow Conditions ◽  
External Gelation ◽  
Flow Geometry ◽  
On Chip ◽  
Spherical Droplets

Abstract Microfluidic on-chip production of microgels employing external gelation has numerous biological and pharmaceutical applications, particularly for the encapsulation of delicate cargos, however, the on-chip production of microgels in microfluidic devices can be challenging due to problems such as clogging caused by accelerated progress in precursor solution viscosity. Here, we introduce a novel microfluidic design incorporating two consecutive co-flow geometries for microfluidic droplet generation. A shielding oil phase is employed to avoid emulsification and gelation stages from occurring simultaneously, thereby preventing clogging. The results revealed that the microfluidic device could generate highly monodispersed spherical droplets (coefficient of variation < 3%) with an average diameter in the range of 60–200 μm. Additionally, it was demonstrated that the device could appropriately create a shelter of the oil phase around the inner aqueous phase regardless of the droplet formation regime and flow conditions. The ability of the proposed microfluidic device in the generation of microgels was validated by producing alginate microgels utilizing an aqueous solution of calcium chloride as the continuous phase.

scholarly journals Droplet Shape Control Using Microfluidics and Designer Biosurfactants

2020 ◽  
Author(s):  
Yuan Gao ◽  
Chun-Xia Zhao ◽  
Frank Sainsbury
Keyword(s):  
Shape Control ◽  
Protein Film ◽  
Droplet Shape ◽  
Precise Control ◽  
Mechanical Responses ◽  
Emulsion Droplets ◽  
Aspect Ratios ◽  
Surface Active ◽  
Spherical Droplets

<p>Many uses of emulsion droplets require precise control over droplet size and shape. Here we report a ‘shape-memorable’ micro-droplet formulation stabilized by a polyethylene glycol (PEG)-modified protein-surfactant, the droplets are stable against coalescence for months and can maintain non-spherical shapes for hours, depending on the surface coverage of PEGylated protein. Monodisperse droplets with aspect ratios ranging from 1.0 to 3.4 were controllably synthesized with a flow-focusing microfluidic device. Mechanical properties of the interfacial protein network were explored to elucidate the mechanism behind the droplet shape conservation phenomenon. Characterization of the protein film revealed that the presence of a PEG layer at interfaces alters the mechanical responses of the protein film, resulting in interfacial networks with improved strength. Taking advantage of the prolonged stabilization of non-spherical droplets, we demonstrate the possibility of functionalization of the droplet interface with accessible biotin moieties. The stabilization of micro-droplet shape with surface-active proteins that also serve as an anchor for integrating functional moieties, provides a tailorable interface for diverse applications.</p>

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