Nylon microcapsules

Nylon microcapsules with concavalin- Competitive binding Insulin Plasma glucose levels 41,42... 

Enzymes may be immobilized by encapsulation in nonpermanent (e.g., liposomes) or permanent (e.g., nylon) microcapsules. The enzyme is trapped inside by a semi-permeable membrane, where substrates and products are small enough to freely diffuse across the boundary. While nonpermanent microcapsules are useful in biochemical research, only permanent microencapsulations yield analytically useful systems, because of their mechanical stability. 

Nylon microcapsules are formed by the interfacial polymerization of hexa-methylenediamine with sebacoyl chloride.22 The hexamethylenediamine is initially present in an aqueous enzyme solution, while the sebacoyl chloride is present in an organic phase such as 4 1 hexane/chloroform. The two solutions are mixed to form an emulsion. The nylon-6,10 membrane forms around the emulsified microdroplets, at the organic-aqueous interface ... 

Luzzi L, Zoglio M, Maulding H. Preparation and evaluation of the prolonged release properties of nylon microcapsules. J Pharm Sci 1970 59 338-341. 

The widely used organophosphate Insecticide methyl parathlon was the first material to be formulated as a microencapsulated pesticide. This formulation, sold under the tradename PENNCAP-M Insecticide (a registered trademark of Pennwalt Corporation), consists of nylon-type microcapsules which contain the active Ingredient. The capsules are suspended In water and typically have an average particle size of approximately 25 microns (fifty percent by weight of the capsules have a particle size of 25 microns or more). Upon application by conventional spray equipment the water evaporates, and the active Ingredient Is slowly released over an extended period of time. 

Figure 8.32 Process for the preparation of nylon 6.10 microcapsules by interfacial polymerisation the hexamethylenediamine in the aqueous phase reacts with the sebacoyl chloride in the nonpolar phase to form on interfociol polyamide film.

Encapsulation. Immobilization of enzymes by encapsulation within semipermeable structures dates back to the 1970s. There are three fundamental variations of this approach. In coacervation, aqueous microdroplets containing the enzyme are suspended in a water-immiscible solvent containing a polymer, such as cellulose nitrate, polyvinylacetate, or polyethylene. A solid film of polymer can be induced to form at the interface between the two phases, thereby producing a microcapsule containing the enzyme. A second approach involves interfacial polymerization in which an aqueous solution of the enzyme and a monomer are dispersed in an immiscible solvent with the aid of a surfactant. A second (hydrophobic) monomer is then added to the solvent and condensation polymerization is allowed to proceed. This approach has been used extensively with nylons, but is also applicable to polyurethanes, other polyesters, and polyureas. 

Encapsulation achieves the confinement of biological components by using various semi-permeable membranes. Encapsulation allows for the enzymes to exist freely in solution, which is confined within the small area surrounded by the membrane. Macromolecules cannot cross the membrane barrier, which is permeable for small molecules only (substrates or products). Nylon and cellulose nitrate are the most popular materials used for the production of microcapsules that need to have a chameter between 10 and 100 pm chameteis. Furthermore, biological cells could be used as capsules as it shown in erythrocytes based sensor. Alternatively enzyme solution can be encapsulated in a thin layer, which covers the electrode and confined between the electrode and semi-permeable membrane surface. ... 

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