Microcapsule membranes with

Xie, R. Chu, L.-Y. Chen, W.-M. Zhao, Y. Xiao, X.-C. Wang, S. Preparation of monodispersed porous microcapsule membranes with SPG membrane emulsification and interfacial polymerization. Gaoxiao Huaxue Gongcheng Xuebao (2003), 17(4), 400-405. 

Enzymes can also be trapped within a nanotubular membrane by capping both faces of the membrane with a thin layer of porous polymer. In effect, arrays of enzyme-filled microcapsules are formed. Small molecules pass through the po-... 

In the biotechnology industry microencapsulated microbial cells are being used for the production of recombinant proteins and peptides. The retention of the product within the microcapsule can be beneficial in the collection and isolation of the product. Encapsulation of microbial cells can also increase the cell-loading capacity and the rate of production in bioreactors. Smaller microcapsules are better for these purposes they have a larger surface area that is important for the exchange of gases across the microcapsule membrane. Microcapsules with semipermeable membranes are being used in cell culture. A feline breast... 

We measured permeation of anionic and cationic electrolyte ions through poly(L-lysine-fl/r-terephthalic acid) microcapsule membranes as a function of pH of the medium at different ionic strengths. The solutes used were 5-sulfosalicylic acid as an anion and phenyltrimethylammonium chloride as a cation. We suspended water-loaded poly(L-lysine-a/r-terephthalic acid) microcapsules in a buffer solution and mixed this with a 5-sulfosalicylic acid solution or phenyltrimethylammonium chloride solution. The final concentration of the microcapsules is 20 % (v/v). We determined the solute concentration in the suspension medium spectrophotometrically at suitable time intervals after separating microcapsules by centrifugation and filtration through a Millipore filter. 

Capsule membranes with an adsorbed polyelectrolyte layer through which the permeation of solutes is dramatically altered in response to small changes in pH would be useful in constructing a functional encapsulated enzyme system in which the initiation/termination of an enzymatic reaction could be controlled. PSt microcapsules with copoly(MA, St) or PIE seem to be well suited for this purpose, since their permeability alters rapidly over a very narrow pH range as a result of changes in the configuration of the adsorbed polyion. The present section describes the on/off control of an enzyme reaction using pH-sensitive PSt microcapsules with copoly(MA, St). 

Microcapsules with a narrow size distribution containing oily core material can be prepared by a Shirazu porous glass (SPG) emulsification technique, followed by a suspension polymerization process. The SPG membrane is a special porous glass membrane with very uniform pore size. Guang Hui Ma et al. have reported the preparation of microcapsules containing hexadecane (oil core) using poly(styrene-... 

Due to the well-known enzymatic lability or environmental sensitivity of proteins, a common characteristic among protein delivery systems is the ability to protect the protein from the external environment. Modes of protection may be chemical or physical. A well-recognized system that provides physical protection of proteins is microcapsules, in which a solid membrane separates the solid contents of the microcapsule from the external environment. An alternative approach would be to replace a solid membrane with a liquid membrane, i.e., multiphase or multiple emulsions. Multiple emulsions may be prepared as either oil-in-water-in-oil (OAV/0) or water-in-oil-in-water (W/OAV) systems. Multiple-emulsion systems, for the purpose of delivering proteins, would be comprised of an interior aqueous phase, containing the water-soluble protein, separated from the external aqueous phase by an oil phase, i.e., W/OAV emulsions (Fig. 1). Multiple emulsions, therefore, provide an alternative technique for the encapsulation of proteins and other materials that would otherwise be metabolized, rapidly cleared, or toxic to the patient. Multiple emulsions have been utilized for parenteral and oral administration (Brodin et al, 1978). Although there is a physical resemblance to microcapsules, multiple... 

Microcapsules can be used for mammalian cell culture and the controlled release of drugs, vaccines, antibiotics and hormones. To prevent the loss of encapsulated materials, the microcapsules should be coated with another polymer that forms a membrane at the bead surface. The most well-known system is the encapsulation of the alginate beads with poly-L-lysine. 

A new variation of interfacial polymerization was developed by Russell and Emrick in which functionalized nanoparticles or premade oligomers self-assemble at the interface of droplets, stabilizing them against coalescence. The functional groups are then crosslinked, forming permanent capsule shells around the droplets to make water-in-oil (Lin et al. 2003 Skaff et al. 2005) and oil-in-water (Breitenkamp and Emrick 2003 Glogowski et al. 2007) microcapsules with elastic membranes. 

Microcapsule properties make them attractive materials for a wide variety of practical applications. In the area of catalysts, microcapsules provide semipermeable membranes that are readily produced and dispersed. These properties, along with others, have inspired systems that include synthetic or man-made encapsulated catalysts, such as organocatalysts, metal particles, enzymes, and organometallic... 

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