Yolk structured particles

Hollow inorganic particles have various potential applications such as in coatings catalysis, adsorption, and drug dehvery system (DDS) due to their imique structural features [90]. The porous shell provides diffusion pathways to their interior voids, which is particularly important for catalysis and drug dehvery. Fiuther-more, the yolk-shell structured particles containing functional cores inside the hollow interior are useful as nanoreactors for various catalytic reactions and multifunctional carriers for drug dehvery [91]. 

The structure of the interfacial layers in food colloids can be quite complex as these are usually comprised of mixtures of a variety of surfactants and all are probably at least partly adsorbed at interfaces which even individually, can form complex adsorption layers. The layers can be viscoelastic. Phospholipids form multi-lamellar structures at the interface and proteins, such as casein, can adsorb in a variety of conformations [78]. Lecithins not only adsorb also at interfaces, but can affect the conformations of adsorbed casein. The situation in food emulsions can be complicated further by the additional presence of solid particles. For example, the fat droplets in homogenized milk are surrounded by a membrane that contains phospholipid, protein and semi-solid casein micelles [78,816], Similarly, the oil droplets in mayonnaise are partly coated with granular particles formed from the phospho and lipo-protein components of egg yolk [78]. Finally, the phospholipids can also interact with proteins and lecithins to form independent vesicles [78], thus creating an additional dispersed phase. 

The stmeturai units of liposomes are ainphiphile molecules, mainly phospholipids. Alec Bangham and co-workers observed self-closed lipid structures after they had been dissolved in water [35]. This first observation took place after egg yolk lecithin had been dispersed in water. According to D.D.Lasic and D. Papahadjopoulos, liposomes are self-assembling colloidal particles in which a lipid bilayer encapsulates a fraction of the surrounding medium [36]. 

The structures of egg yolk low-density lipoproteins have also been examined (Kamat et al.y 1972). These lipoproteins differ from plasma low-density lipoproteins mainly in the compositon of the non-polar lipids. Thus there is only about 0.8% of the particle weight of cholesteryl esters, whereas there are about 60% triglycerides. It follows that the particles with a diameter of about 300 A consist of a liquid core of neutral lipids covered by phospholipids and proteins. 

The Co Si02 yolk-shell structure was obtained by thermal reduction of CoO Si02 core-shell particles via volume contraction of CoO to Co. The Co Si02 yolk-shell nanocatalysts exhibited high activity and reusability for phenoxycarbonylation of iodobenzene. In addition, the magnetic property of the cobalt cores permitted facile separation of the catalysts from the products. 

A, Ar -(l,2-dihydroxyethylene)bisacrylaini(le) are known. The periodate-mediated cleavage was used for the generation of hollow microgels and yolk/shell structures [34,396]. After cleavage, the linear chains can penetrate the shell, leading to hollow particles. 

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