Micro-multiple emulsions

The entrapment efficiency was 88.5% to 93.7% (Table 9.1). This may be attributed to noncoalescence of internal droplets despite the second sonication step. Gelling of the oil phase upon congealing imparts stability to internal droplets and results in less expulsion/breaking of droplets and drug dumping in the external phase. The entrapment efficiency correlates with micro-multiple emulsion reported by Morel et al. (1994). 

The examples given here involve lung surfactant replacement compositions and surfactant systems used for 2D protein crystallization. Other potential systems include direct, reverse and multiple emulsions for drug and gene delivery, as well as micro- and nano-sized gas bubbles for O2 delivery and diagnosis [3, 4]... 

The chapter has dealt with the stability and stabilisation of colloidal systems and covered topics such as their formation and aggregation. If the particle size of a colloidal particle determines its properties (such as viscosity or fate in the body), then maintenance of that particle size throughout the lifetime of the product is important. The emphasis in the section on stability is understandable. Various forms of emulsions, microemulsions and multiple emulsions have also been discussed, while other chapters deal with other important colloidal systems, such as protein and polymer micro- and nanospheres and phospholipid and surfactant vesicles. 

A. T. Florence and D. Whitehill. Stability and stabilization of water-in-oil-in-water multiple emulsions. In Macro- and Micro-Emulsions (ed. D. O. Shah), ACS Symposium Series No. 272, American Chemical Society, Washington DC, 1983, pp. 359-80... 

The control that can be exerted over the flow of immiscible fluids in micro-fluidic devices to formation of monodisperse droplets and bubbles can be extended to formation of more complicated objects and architectures of the droplets, such as multiple emulsions [27-32], Janus particles [33, 34] and other morphologies of liquid droplets, solidified particles and capsules [35-39], Figure 13 presents micrographs of the droplets, particles and capsules produced in exemplary techniques. 

Lin W, Yang XL, Winston Ho W. Fheparation of nniform-sized multiple emulsions and micro/nano particulates for drug delivery by membrane emulsification. Journal of Pharmaceutical Sciences. 20H 100(l) 75-93. 

Higashi et al. (22), described a new method of producing W/O/W multiple emulsions by a membrane emulsification technique. This method permits the formation of monodis-persed liquid microdroplets containing aqueous micro-... 

Sugiura S, Nakajima M, Yamamoto K, Iwamoto S, Oda T, Satake M, Seki M. 2004a. Preparation characteristics of water-in-oil-in-water multiple emulsions using micro-channel emulsification. J Colloid Interface Sci 270 221-228. 

During the last decade O/W/O multiple emulsions have been researched as a potential prolonged release vehicle for oily soluble entrapped addenda. These systems also hold promise for infinite applications in micro- and nanoencapsulation of organic and inorganic active molecules. New forms are exhibiting the long-term stability necessary for release control. 

Polymer emulsions are aqueous fluids which present a medium for the multiplication of micro-organisms (bacteria, fungi, yeasts). As the emulsions are used for the production of high quality products, including those coming in contact with food, they have to be in a clean condition when used, that means in-tank protection to prevent microbes from proliferating is necessary. 

Figure 7.4 HPLC chromatograms of (a) nifedipine-loaded O/W/O multiple micro-emulsion (nifedipine concentration 20g ml ), (b) 20% decomposed nifedipine-loaded OAV/O multiple microemuision, (c) totally decomposed nifedipine-loaded O/W/O multiple microemuision, and (d) placebo O/W/O multiple microemuision. (Adapted from Castro et al., 2001.)...

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