Synthetic Polymers in Cosmetics
E. Desmond Goddard, James V. Gruber in Principles of Polymer Science and Technology in Cosmetics and Personal Care, 1999
It is felt that the presence of the polymer/surfactant coacervate is important for deposition of the polymer onto the anionic surfaces of hair and skin (159). It has been demonstrated that when a cationic polymer is deposited onto hair as a coacervate, subsequent rinsing removes the anionic surfactant more quickly than the bound polymer. In these electokinetic measurements, the overall charge of the hair gradually becomes more cationic. It should be kept in mind, also, that coacervate can form when a concentrated anionic surfactant solution containing a solubilized cationic polymer is diluted by the addition of water. This is the typical mode of application of conditioning shampoos to hair and skin during washing. The deposition occurs during the rinsing cycle and is appropriately termed “dilution deposition.”
Cell and Extracellular Matrix Interactions in a Dynamic Biomechanical Environment:
Michel R. Labrosse in Cardiovascular Mechanics, 2018
As the name suggests, elastic fibers easily stretch under load and recoil to their original dimensions when unloaded. Elastic fibers are extremely stable, with a half-life of 40 years (Arribas et al. 2006), helping tissues maintain proper form when healthy, but they have limited repair mechanisms if damaged or degraded. Elastic fibers are macromolecules formed around a core of insoluble elastin, which makes up 90% of the fiber (Sherratt 2009). The other 10% consists of glycoproteins, most commonly fibrillin, in the form of microfibrils that surround the elastin. Like collagen, elastin is also formed by a complex cell-mediated process, whereby cells release the soluble precursor tropoelastin into the extracellular space, where tropoelastin molecules aggregate into coacervate (Czirok et al. 2006). Cellular motion aides the coacervate in assembling, crosslinking, and extending into elastic fibers.
Chemical Modulation of Topical and Transdermal Permeation
Marc B. Brown, Adrian C. Williams in The Art and Science of Dermal Formulation Development, 2019
Coacervation is a somewhat specialised form of ion-pairing and is usually used to describe electrostatically driven liquid–liquid phase separation when oppositely charged macromolecular ions associate; one liquid phase is a concentrated colloidal phase (the coacervate) and the other phase exists as a highly dilute colloidal phase. The term “coacervate” essentially means “to assemble together or cluster” and the coacervate droplets typically have a diameter between 1 and 100 µm. A common example of this phenomenon is when aqueous solutions of the oppositely charged biopolymers gelatin and gum arabic are mixed; a gelatin–acacia coacervate has been used to encapsulate benzocaine in topical formulations.
Microencapsulation of fish oil by casein-pectin complexes and gum arabic microparticles: oxidative stabilisation
Published in Journal of Microencapsulation, 2019
Arianne Cunha dos Santos Vaucher, Patrícia C. M. Dias, Pablo T. Coimbra, Irina dos Santos Miranda Costa, Ricardo Neves Marreto, Gisela Maria Dellamora-Ortiz, Osvaldo De Freitas, Mônica F. S. Ramos
In this work, two processes of microencapsulation were employed: a mechanical (spray drying) and a chemical (complex coacervation) process. Microencapsulation by spray drying occurs in two steps: emulsification of the core oil in the polymer solution followed by removal of the solvent by a hot stream of air (Thies 1996). Water soluble polymers such as modified starches, whey, maltodextrin, beta-cyclodextrin and GA are generally used as wall material (Arslan-Tontul and Erbas 2017). Complex coacervation is based on the ability of cationic and anionic water-soluble polymers to interact in water to form a liquid, polymer-rich phase called a complex coacervate. Dispersion of a water insoluble core material in this system and wetting of this core material by the complex coacervate, results in spontaneous coating of the core material with a thin film of coacervate. In this case, the capsules are formed when this liquid film is solidified (Thies 1996) and spray drying is used to dry the resulting material. A variety of proteins and polysaccharides are used to obtain biopolymer particles, including whey proteins, casein, soy proteins, gelatine, zein, starch, cellulose and pectin (Matalanis et al.2011).
Current trends in PLGA based long-acting injectable products: The industry perspective
Published in Expert Opinion on Drug Delivery, 2022
Omkara Swami Muddineti, Abdelwahab Omri
Microencapsulation technique is used to prepare microspheres, including ionic gelation, spray drying, coacervation, solvent evaporation, extraction, and interfacial polymerization to harden and separate the particles [49]. Out of all the techniques, solvent evaporation/extraction is the most widely used technique for manufacturing the marketed PLGA-based microspheres. Briefly, the solvent evaporation/extraction method depends on the emulsification of the polymer (organic) solution in a continuous (aqueous) phase and later formation of microspheres via precipitation. The solvent used to solubilize the polymer and active pharmaceutical ingredient (API) should have sufficient solubility in the aqueous phase to partition and precipitation to prepare desired microparticles. Coacervation and phase separation technique is also used to manufacture PLGA-based microspheres at higher scales [50]. In this technique, polymer (mixture of polymers) solution is separated into a dilute polymer phase and concentrated coacervate phase, which is in equilibrium. Phase separation can be initiated using a change in temperature, the addition of non-solvent, and a change in ionic strength. Further, these changes induce interaction between polymers over polymer–solvent interaction, resulting in polymer dehydration. Thermal or chemical treatment is frequently used to stabilize the coacervate emulsion droplets to form microspheres, which may not apply to sensitive molecules such as proteins.
Microencapsulation of Lactobacillus plantarum LN66 and its survival potential under different packaging conditions
Published in Journal of Microencapsulation, 2022
Min Zhang, Cheng Yin, Jing Qian
After selecting the optimal conditions for complex coacervation in Section 2.2, the production of the microcapsules was performed according to methodology described by Sohrab Sharifi, with slightly modifications. At the first step, 200 ml GE (2%, w/v) solution was prepared at 40 °C. The probiotic bacterium cells, prepared in Section 2.3.1, were slowly added to the solution. Then, 200 ml of GA (2%, w/v) was added to this mixture, using a 1:1 ratio of biopolymers (GE: GA). The pH of the final solution was regulated to 4.0 by adding a 10% (w/v) acetic acid dropwise slowly to stimulate electrostatically bindings between GE and GA. All of the above stages were done at 40 °C. To ensure completion of the formation of complex coacervate and allowing the separation of the phases, the produced liquid microcapsule was kept at 4 °C for 2 h. Finally, wet microcapsules were freeze dried (Lyobeta 5 PS, Spanish) at −65 °C for 48 h.
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