Kaur et al. Furthermore, this study showed that under the dynamic conditions of emulsification the monolayer of particles is disorganized, despite the ability of the icosahedral virus capsid to form ordered hexagonal arrays. In a further example, He et al. At low particle concentrations rod-shaped particles were oriented parallel to the interface of a perfluorodecalin core, however, at high concentrations segregation at the interface forced the rods to orient perpendicular to the interface, overcoming inter-particle electrostatic repulsion He et al. The use of a fluid-fluid interface as a template for the synthesis of polymer microcapsules encapsulating an active component is an exciting area and a great deal of progress has been made in understanding the interfacial chemistry that is critical to controlling the physicochemical properties of both the encapsulated material and the templated material.
Control of the interfacial tension between the three phases in an emulsion system core, aqueous, and stabilizer is a fundamental concern when designing a template emulsion and one approach is to use solid nanoparticles as the stabilizer to form a Pickering emulsion. This potentially alters the properties of the dispersed phase leading to changes in the particle contact angle, which may result in a reduced capacity of particles to stabilize the interface. The authors found that for both toluene and olive oil dispersed phases, when the GO concentration was increased, the formed droplets became smaller, suggesting that GO was acting as a limiting interfacial stabilizer.
They also discovered that when olive oil was used as the dispersed phase, multiple emulsions were formed spontaneously, a phenomenon which was not observed with toluene as the dispersed phase Figure 2A. They suggest that this unusual multiple emulsion formation is due to the more complex mixture of components in the olive oil.
Furthermore, with toluene, droplet size increased with pH while droplet stability decreased, resulting in mostly coalescence at pH 11, however when olive oil was used, the opposite was seen to be the case—droplets became smaller and more stable with an increase in pH. A minor component of olive oil, oleic acid, is deprotonated at pH 11 to form sodium oleate which is an effective emulsifier and acts to stabilize the emulsions at higher pH.
This work highlights the potential for minor components of the core material to play a critical role in the formation and stability of the final emulsion. Figure 2. Examples of how core composition can affect the structure of fluid-fluid interfaces and resultant templated microcapsules. A Fluorescence and transmission optical micrographs showing multiple emulsion formation for olive oil and single emulsion formation for toluene with aqueous GO solutions; i fluorescence image of an olive oil emulsion, ii fluorescence image of a toluene emulsion, iii optical microscopy image of an olive oil emulsion, iv optical microscopy image of a toluene emulsion.
Reprinted with permission from Ali et al.
Atomic Force Microscopy Captures the Liquid/Liquid Interface
B The changing morphology of poly methyl methacrylate microcapsules when the core composition is modified between i Hexadecane, ii hexyl salicylate, iii cyclamen aldehyde, and iv toluene. Reprinted with permission from Tasker et al. Work conducted by Tasker et al. Although a surfactant is not considered a particle in the traditional sense, this work demonstrates how changing interfacial properties resulting from substitution of the core phase can impact the formation of an emulsion-based polymer microcapsule template.
In their study the authors used poly methyl methacrylate as the shell-forming polymer using the solvent evaporation method of microcapsule formation with a range of oils and aqueous phases to understand the importance of the correct interfacial behavior. The authors found that when cetyltrimethylammonium bromide was used as the stabilizer and hexadecane was used as the oil phase, acorn morphology microcapsules were formed, whereas when hexadecane was substituted for toluene, cyclamen aldehyde, dihydromyrcenol, or hexyl salicylate, core-shell microcapsules were produced Figure 2B.
This is likely an effect of the hydrophobicity of the oils chosen, as the partition coefficient of hexadecane is much higher than that of the other oils tested. The work demonstrated that interfacial tension and contact angle measurements can help predict whether a given oil-polymer surfactant combination chosen to create a polymer microcapsule will result in desired morphologies. Polarity of the oil phase is a further physicochemical property that has been considered in depth when considering the formation of Pickering emulsions.
The polarity of the oil phase can determine what type of emulsion is formed, if any, which again highlights the importance of considering interfacial tension and contact angle measurements in the design of any complex emulsion situation Binks and Clint, ; Read et al.
The effect of core composition on emulsion stability is also evident when using complex cores with melting points near room temperature. Veverka et al. They found that using conjugated linoleic acid CLA as the oil phase in a molar ratio with the aqueous phase, using no additional stabilizer, yielded an emulsion which was fully phase separated within 48 h.
In comparison, when using cocoa butter as the oil phase, again in a ratio, a stable emulsion up to 12 months was produced. The authors state that this stability is due to the nature of the cocoa butter, as it contained crystalline particles of saturated fatty acids, as demonstrated by cryo-SEM, and saturated fatty acids are known to behave as solids at the oil-gel interface Macierzanka et al.
This work demonstrates how the core composition is an important parameter to consider when forming an emulsion, as in this case, the presence of particles within the oil actually allowed the unintentional formation of a Pickering emulsion. The chain length of core oils can also affect microcapsule morphologies. For example, Wagdare et al. The authors used long chain triglycerides, such as olive oil, coconut oil, and vegetable oil, and the medium chain triglyceride Miglyol, in addition to jojoba oil which is a mixture of monoesters.
They found that for the long chain triglycerides, a single core-shell morphology was obtained, but when the medium chain triglyceride was used, multi-compartment core-shell morphologies were obtained. They explain the differences in behavior between the long- and medium-chain triglyceride core oils to be due to their compatibility with the shell material. As the solvent diffuses out of the formed droplets, the concentrations of both the polymer and the oil in the droplet increase. If the oil has already phase separated before the polymer solidifies, the oil can diffuse through the polymer matrix to form a large droplet in the middle of the capsule.
Higher molecular weight molecules are less soluble in general than their smaller counterparts and so phase separation will occur at an earlier stage in the capsule formation which explains the difference in morphologies seen for capsules formed using the different oils in this study. In other cases it has been found that the ratio of components that make up a microcapsule core can also affect the resulting capsule morphology. Wang et al. They found that the resulting morphology of the formed polymer capsules could be controlled by adjusting the composition of the oil phase, resulting in either a single void inside the polymer shell, or a multi-component core.
Firstly, they note that in the absence of BPA, a single void structure is formed, and this is attributed to the presence of hexadecane, which acts as a non-solvent for the formed polymer, driving it to the oil-water interface where it forms a shell. However, when BPA is added to the oil phase, the internal structure of the capsule changes to what appears to be a series of sub capsules within the external shell.
- The Discovery of Isotopes: A Complete Compilation!
- NPTEL :: Chemical Engineering - Interfacial Engineering?
- Dictionary of computer terms;
- The Devil Served My Dinner;
- Servicios Personalizados!
- Impact of Public Policy Measures on the German Real Estate Market;
They found that by increasing the BPA concentration in the oil phase, the number of internal cores increases but the cores also decrease in size and, as expected, the shell thickness of the whole capsule decreases as less polymer migrates to the interface. This article demonstrates the importance of considering the effect that changing the composition of a complex cargo could have on the morphology of microcapsules.
In other works which exemplify this, Liu et al.
The microparticles are formed as the solvent evaporates from the core, resulting in shrinkage of the emulsion droplets, and polymer precipitation. Similarly, Hitchcock et al. They found that by replacing toluene with hexyl salicylate in the microcapsule core, the nanoparticles adsorbed to the polymer microcapsules in an aggregated, fractal pattern on the polymer surface, with the equivalent of up to eight monolayers forming on one surface as opposed to the dense monolayer coverage observed on the toluene core microcapsules.
This is particularly relevant in the field of drug delivery where the drive to incorporate higher concentrations of drug increases the influence of the physicochemical properties of the drug on the emulsion core. The formation and resulting structure of nature's highly defined self-assembling nanocapsules, viruses, is highly sensitive to the composition of the core template and serves as a guiding example to other microcapsule fields.
Indeed, computational simulation of assembly has shown that the strength of the interactions between viral subunits and the core, relative to inter-subunit interactions, is a governing principle on assembly around cores that do not match the preferred empty particle geometry Elrad and Hagan, Our review of recent literature suggests that minor changes in core composition, particularly toward more complex systems, can play a critical role in the stability of many fluid-fluid interfaces, by altering the interfacial properties of the system, ultimately impacting the final structure of templated capsules.
We believe that continued efforts to understand the fundamental forces that drive the stability of fluid-fluid interfaces in complex mixtures will ultimately underpin further advancement in the field. AT and FS jointly led the initial literature search and drafting. All authors contributed equally to the final writing of the manuscript. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Ali, M. Synthesis and characterization of graphene oxide—polystyrene composite capsules with aqueous cargo via a water—oil—water multiple emulsion templating route.
ACS Appl. Interfaces 9, — Amalvy, J. Synthesis of sterically stabilized polystyrene latex particles using cationic block copolymers and macromonomers and their application as stimulus-responsive particulate emulsifiers for oil-in-water emulsions. Langmuir 20, — Ashley, C.
Cell- specific delivery of diverse cargos by bacteriophage MS2 virus-like particles. ACS Nano 5, — Aveyard, R. Emulsions stabilised solely by colloidal particles. Colloid Interfaces Sci. Binks, B. Solid wettability from surface energy components: relevance to pickering emulsions. Langmuir 18, — Contact angles in relation to emulsions stabilised solely by silica nanoparticles including systems containing room temperature ionic liquids.
Brasch, M. Assembling enzymatic cascade pathways inside virus-based nanocages using dual-tasking nucleic acid tags. Chang, C. Curvature dependence of viral protein structures on encapsidated nanoemulsion droplets.
Publications: Dagastine Research Group, Chemical Engineering, The University of Melbourne
ACS Nano 2, — Chudasama, V. Recent advances in the construction of antibody-drug conjugates. Duncan, R. Polymer therapeutics as nanomedicines: new perspectives. Elrad, O. Mechanisms of size control and polymorphism in viral capsid assembly. Nano Lett. Enomoto, T. Viral protein-coating of magnetic nanoparticles using simian virus 40 VP1. Frasch-Melnik, S. Food Eng. Ghosh, S. Fat crystals and water-in-oil emulsion stability. Glasgow, J.
- Dont Talk to Strangers: A Novel (Keye Street, Book 3);
- Effective Grading: A Tool for Learning and Assessment (Jossey-Bass Higher and Adult Education).
- Sacred Mirror: Nondual Wisdom and Psychotherapy.
- Advanced Science News.
- PhD Position - Electrochemically controlled crystallization at the liquid-liquid interface.
Osmolyte-mediated encapsulation of proteins inside MS2 viral capsids. ACS Nano 6, — Han, F. Bioerodable PLGA-based microparticles for producing sustained-release drug formulations and strategies for improving drug loading. He, J. Langmuir 25, — Hitchcock, J. Adsorption of catalytic nanoparticles onto polymer substrates for controlled deposition of microcapsule metal shells.
Langmuir 34, — Hu, Y. Packaging of a polymer by a viral capsid: the interplay between polymer length and capsid size. Kaur, G. Interfacial assembly of turnip yellow mosaic virus nanoparticles. If you need any of your orders' to be delivered outside of India, please reach out to us via our contact us page with the product details and delivery location for us to quote you the best possible shipping price. Comics And General Novels.
It carries the prestige of over 47 years of retail experience. SapnaOnline provides online shopping for over 10 Million Book Titles in various languages and genres. Shopping is made easy through the easy checkout process with High Security offerings like Bit SSL Certificate provided by Global Safe Security Providers-Verisign so that your online transactions are absolutely safe and secured. At SapnaOnline we believe that customer satisfaction is utmost important hence all our efforts are genuinely put into servicing the customer's in the best possible way.
SapnaOnline offers Free shipment all across India for orders above Rs and Global Shipment at the most economical cost. Shop with an easy mind and be rest assured that your online shopping experience with SapnaOnline will be the best at all times. Our website is secured by bit SSL encryption issued by Verisign Inc , making your shopping at Sapnaonline as secure as possible.
Hello World, this is a test. Login Please enter your login details. Forgot password? Remember Me? Forgot Password? It happens, just reset it in a minute. Sorry, incorrect details. Welcome back pal! Please enter your User Name, email ID and a password to register. International Shipping at best shipping prices! Notify Me We will send an email as soon as we get it in stock.
Write a Testimonial Few good words, go a long way, thanks! Personalize Gift card We will send an email to receiver for gift card. Continue Shopping Checkout. Reset Pincode. Submit a Review.