Encapsulation procedures

Insulin (molecular weight 7000) has been formulated in controlled release microbeads and pellets (135,136). A solvent evaporation micro-encapsulation procedure was used to produce microspheres with up to 20% by weight insulin. Solvent-casting techniques were used to prepare pellets. The investigations demonstrated that the PLA... 

This encapsulation procedure gives the highest activity for the lipases. The lecithin/ amines mixture structuring the pore network leads to a suitable phospholipids bilayer-like environment, which avoids the necessity to create an interface by substrate assembly. Monduzzi and coworkers compared the activity of lipase that was immobilized on SBA-15 physically, or chemically with glutardialdehyde [200]. 

Chemisorption. A key step in the development of a successful membrane modified FET is the adherence and longevity of the membrane and the success of the encapsulation procedure. Sudholter et al (35) have proposed a method for the attachment of the ion selective membrane to a silylated SiC>2 gate oxide. An organofunctional silane, for example methacryloxypropyl trimethoxysilane, forms a bond between the surface and a photocrosslinkable polymer (eg polybutadiene). The ionophore would be directly bound to the polymer backbone, thus eliminating the need for plasticiser. Without any further modification with ionophore the membrane is sensitive to pH and shows a long life time (some months). Similar approaches have also been proposed by other workers, eg (36)... 

Application of the template encapsulation procedure to the rigid cyclohexanediaminate Ze(3-[Co(chxn)3] cation has yielded a high symmetric cage systems [107]. For the synthesis of the diaminocyclohexane sarcophaginates, the condensation procedure was modified (pH ll-rl2 and elevated temperatures) compared with that for ethylenediamine sarcophaginates. 

UV spectra used for a semi-quantitive determination of the amount of intracrystalline phthalocyanine complexes were taken on a Perkin Elmer UV-visible spectrophotometer. A calibration curve was obtained by dissolving known amounts of metal complex in concentrated sulfuric acid. Zeolite was added to take into account matrix effects. Surface area and pore volume measurements were performed on a Micromeritics ASAP 2000 by absorption of nitrogen gas at liquid nitrogen temperature. X-ray powder diffraction of the zeolites was used to ensure good crystallinity after the exchange and encapsulation procedures... 

Unfortunately, the CFT process is hm-ited to dmgs with molecular weights smaller than 80 kDa. Alternatively, encapsulation of material with higher molecular weight, e.g., reporter plasmids (pDNA), in gas-fiUed microspheres can be performed by spray-drying or double-emulsion procedures [57]. Due to the energy impact in the case of double-emulsion procedures, for example, it is common to protect and stabilize the pDNA with polycations such as polylysine or polyethyleneimine. Fig. 7.12 schematically summarizes some of the encapsulation procedures. 

Microspheres obtained using this procedure had an average diameter of 5 pm and narrow size distribution (Fig. 6.3). Figure 6.4 shows that the DNA plasmid survived the encapsulation procedure with super-coiled and relaxed conformations intact. 

The absence of significant differences between the XRD patterns (not shown) of NaY and Co(acac)2trien NaY confirms that there is no significant loss in the zeolite s crystallinity after the encapsulation procedure. 

Thies, C., Biopolymers and complex coacervation encapsulation procedures. Agro Food Industry Hi Tech, 24(4) (2013) 50-52. 

Release of Drug from a Spherical Pellet of a Homogeneous Matrix Such system is obtained using the emulsion solvent removal method and other methods of encapsulation such as congealable disperse phase encapsulation procedure in molten wax. HiguchP derived two equations for predicting the release rate from spherical matrices. 

The new encapsulation procedure is particularly useful for the preparation of carbon fiber disk electrodes of different disk diameters. Furthermore, the new encapsulation technique give a possibility to insulate microelectrodes more reproducibly and to automatize this process if necessary. 

Eguizabal A, Lemus J, Urbiztondo M, Moschovi A.M, Ntais S, Nikolakis V, Soler J, Pina MP. Ammonium based ionic liquids immobilized in large pore zeolites Encapsulation procedures and proton conduction performance. J Power Sources 2011 196(9) 4314-4323. 

Chemical stability may also be surface-related. The lipid exposure at the surface influences the oxidation sensitivity of cholesterol in a dairy-type powder. An encapsulating procedure using gelatine during the drying process enhances the chemical stability of... 

As for animal cell entrapment in hydrogel microparticles or microcapsules, encapsulation procedure should proceed under physiological conditions within a short time (20-30 min), in order to provide cell viability, and to be as simple as possible because all manipulations are carried out under strictly sterile conditions. Taking into account all these requirements, it should be noted that the list of polymer materials and methods for animal cell encapsulation is rather limited. So-called alginate-based carriers (microparticles, micro- and nanocapsules) assure the favorable polymer systems for animal cell immobilization. 

In order to keep alive cells or to avoid denaturation of proteins, DNA or other nonstable BAG, the methods for preparation of nano- or microparticle-based systems should be rather soft providing encapsulation procedure under physiological conditions (pH, temperature, etc.). We cannot describe in detail all methods presently used for bioencapsulation in nano- and microparticles (microcapsules) but would like to discuss some of them which are presently widely employed, or are rather promising to be used in the nearest future. All presently existing techniques for nano- and microcapsule production for biotechnological and biomedical applications are reviewed by Ian Marison et al. [16]. 

It is therefore easy to understand that the encapsulation procedures will open up a much larger and different market for essential oil/terpene products. Experience from all the areas mentioned previously can be applied to the study of volatile compounds in products. 

In the area of essential oils and lower terpenes, simple encapsulation procedures from the area of drug delivery are applied. The essential oils or single active constituents are mixed with a hydrophilic polymer and spray dried using a commercial spray drier. Depending on whether we have an emulsion or a solution of the volatile fraction in the polymer, we obtain monolithic particles or normal microcapsules. 

The encapsulation of essential oils in a hydrophilic polymer may stabilize the constituents of the oil, but a better technique for this purpose will often be to use cyclodextrins in the encapsulation procedure. The use of cyclodextrins will lead to a complexation of the single compounds, which... 

Fig. 9-27. Simplified encapsulating procedure. Courtesy Hull Corp.)...

Several different hydrogels have heen investigated to determine the eflficacy of encapsulation therapy as treatment for multiple diseases in a variety of animal models. For instance, alginate-polylysine-alginate microcapsules have been employed to encapsulate islets and to reverse the effects of diabetes in rats and mice. The mild encapsulation procedure preserved the... 

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