Multilayer shells

The multilayer shells can also provide a protective barrier for the loaded enzyme in environments where enzyme-degrading substrates such as proteases may be present [67]. Dissolved catalase was inactivated immediately by protease, losing its entire activity within 60 min in solution. For catalase loaded in BMS spheres, inactivation is slower, with an activity loss of about 20 % in 60 min. Notably, a negligible decrease in... 

Lvov, Y. and Caruso F. (2001) Biocolloids with ordered urease multilayer shells as enzymatic reactors. Analytical Chemistry, TS, 4212-4217. 

Ng V, PI G, Ss S-C et al (2007) Nanoencapsulation of stem cells within polyelectrolyte multilayer shells. Macromol Biosci 7 877-882... 

The development of novel methods that allow probing the mechanics of colloidal scale shells is a prerequisite for gaining understanding of the physico-chemical mechanisms that govern shell mechanics. This however requires also an in depth treatment of the shell deformation problem under the specific circumstances of the experiment. Both aims are subject of this paper for the particular case of polyelectrolyte multilayer shells investigated with the colloidal probe AFM technique. While the experimental... 

Garcia-Santamaria F, Ibisate M, Rodriguez 1, Meseguer F, Lopez C (2003) Photonic band engineering in opals by growth of Si/Ge multilayer shells. Adv Mater 15 788... 

We intend to implement the new fabrication techniques of conical-like multilayer shells, by exploiting both the know-how already acquired to build flat multilayer coatings and that acquired for building the SAX and JETX mirrors. 

I.L. Radtchenko, G.B. Sukhorukov, and H. Mohwald, A novel method for encapsulation of poorly water-soluble dmgs precipitation in polyelectrol3de multilayer shells, bit. J. Pharm., 242, 219-223 (2002). 

A detailed study of the influence of nanocapsules with a multilayer shell on cell viability and cell penetration ability was very recently presented by Lukasiewicz and Szczepanowicz. Poly(L-lysine) polycations and poly(L-glutamic acid) polyanions were used to build the capsule walls and the PEG-ylated outer layer was introduced to render the system biocompatible. The authors showed the influence of the number of layers, surface charge, and the presence of outer PEG-ylated layer on the cytotoxicity of the formulation. An increase in a number of layers and positive surface charge led to a stronger negative effect on the cells, while PEG-ylation of the outer layer was beneficial. Interestingly, such PEG-modified nanocapsules were easily internalized by human embryonic kidney 293 (HEK 293) cells. 

In another approach, core-shell particles with multilayer shells have been prepared using a layer-by-layer assembly technique [83]. Multicore composite particles have also been reported by Shin et al. [84]. 

FIGURE 11-1 Multilayered shells A. spherical particle with one concentric shell B. equivalent homogeneous particle as long as the physical scale of the nonuniformity of the imposed field is much larger than the particle radius R, the external field of the equivalent particle is indistinguishable from that of the heterogeneous particle... 

The development of LbL assembly for use in food industry mainly involves oil droplets that are coated with multilayered interfaces, leading to (1) improved stability of oil-in-water emulsions, (2) controlled/triggered release of materials either in the core or in the multilayered shell, and (3) hollow capsules as carriers for active ingredients. For example, oil emulsions coated with multilayered sodium dodecyl sulfate (SDS)-chit-osan-pectin showed significantly improved stability against multiple freeze-thaw cydes. Also, multilayer-protected emulsions display better stability against lipid oxidation. However, all these examples are still in the devdopment phase, with continuing efforts to put in practical use. 

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