Micro/nano emulsion

Improved bioavailability. More than 40% of the NCEs (new chemical entity) discovered have good membrane permeability but poor aqueous solubility (i.e.. Biopharmaceutics Classification System II). By formulating the NCE in solution inside a Softgel (e.g., lipid based) or in micro/nano emulsion, the solubility and hence the bioavailability of the compound may be improved. ... 

Biphasic Drug delivery methods Micro/Nano emulsions. 

Spemarth, L. and Magdassi, S. (2007) Preparation of ethylcellulose nanoparticles from nano-emulsion obtained hy inversion at constant temperature. Micro el Nano Letters, 2, 90-95. 

Morales, D., Gutierrez, J.M., Garcia-Celma, M.J., and Solans, Y.C. 2003. A study of the relation between bicontinuous micro emulsions and oil/water nano-emulsion formation. Langmuir 19 7196-7200. Mosca, M., Ceglie, A., and Ambrosone, L. 2008. Antioxidant dispersions in emulsified olive ods. Food Res. Int. 41 201-207. 

Garti, N. Yuli-Amar, I., Micro- and nano-emulsions for delivery of functional food ingredients. In Delivery and Controlled Release of Bioactives in Foods and Nutraceuticals, Garti, N., (Ed.) Woodhead Publishing Limited, Cambridge, U.K., 2008, pp. 149-183. 

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. 

Parvinzadeh, M. and Hajiraissi, R. (2008) Effect of nano and micro emulsion silicone softeners on properties of polyester fibers. Tenside Surfactants Detergents, 45 (5), 254-257. 

Recently, the synthesis of nano-sized HA has been proposed via reverse-micro-emulsion preparation, which is reported to be effective for controlling the hydrolysis and polycondensation of the alkoxides of the constituents. Using this preparation route, the nanoparticles crystallize directly to the desired phase at the relatively low temperature of 1050 °C and maintain surface areas higher than 100 m g after calcination at 1300 °C for 2h [107-109]. 

In principle, the long-term stability can be greatly improved by replacing the internal (macro)emulsion by a wawoemulsion or, better still, a thermodynamically stable micro-emulsion. (We note that, in this context, the prefix micro denotes an entity that is smaller than nano )... 

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]... 

Nano-sized PtRu catalysts supported on carbon have been synthesized from inverse micro emulsions and emulsions using H2PtClg (0.025 M)/RuCl3 (0.025 M)/NaOH (0.025 M) as the aqueous phase, cyclohexane as the oil phase, and NP-5 or NP-9) as the surfactant, in the presence of carbon black suspended in a mixture of cyclohexane and NP-5-I-NP-9 [164]. The titration of 10% HCHO aqueous solution into the inverse micro emulsions and emulsions resulted in the formation of PtRu/C catalysts with average particle sizes of about 5 nm and 20 nm respectively. The RuPt particles were identified by X-ray diffraction. X-ray photoelectron, and BET techniques. All of the catalysts prepared show characteristic diffraction peaks pertaining to the Pt fee structure. XPS analysis... 

Microemulsions are macroscopically isotropic mixtures of at least a hydrophilic, a hydrophobic and an amphiphilic component. Their thermodynamic stability and their nanostructure are two important characteristics that distinguish them from ordinary emulsions which are thermodynamically unstable. Microemulsions were first observed by Schulman [ 1 ] and Winsor [2] in the 1950s. While the former observed an optically transparent and thermodynamically stable mixture by adding alcohol, the latter induced a transition from a stable oil-rich to a stable water-rich mixture by varying the salinity. In 1959, Schulman et al. [3] introduced the term micro-emulsions for these mixtures which were later found to be nano-structured. 

Within the last 30 years, micro emulsions have also become increasingly significant in industry. Besides their application in the enhanced oil recovery (see Section 10.2 in Chapter 10), they are used in cosmetics and pharmaceuticals (see Chapter 8), washing processes (see Section 10.3 in Chapter 10), chemical reactions (nano-particle synthesis (see Chapter 6)), polymerisations (see Chapter 7) and catalytic reactions (see Chapter 5). In practical applications, micro emulsions are usually multicomponent mixtures for which formulation rules had to be found (see Chapter 3). Salt solutions and other polar solvents or monomers can be used as hydrophilic component. The hydrophobic component, usually referred to as oil, may be an alkane, a triglyceride, a supercritical fluid, a monomer or a mixture thereof. Industrially used amphiphiles include soaps as well as medium-chained alcohols and amphiphilic polymers, respectively, which serve as co-surfactant. 

ZnS nano crystals were synthesised in ternary w/o micro emulsion stabilised by non-ionic or cationic surfactants [44]. Several morphologies, e.g. nanorods or spherical or ellipsoidal ZnS particles were obtained by varying the to values. The product morphology was also found to be function of the absolute reactant concentration and concentration ratio of Zn2+ to S2, the incubation time and the ambient temperature. 

In summary, the use of micro emulsions offers several advantages for the combustion process. Besides the thermodynamic stability of the aqueous fuel (which automatically means that the energy input for the production is minimal), water, surfactants and freezing point-decreasing components that are homogeneously distributed on a nano-scale can be optimally used for the reduction of soot and NOx emissions. 

In this study, after a brief introduction to PI we provide the bases of a technique for the preparation of polymeric micro-porous materials, known as polyHIPE polymers (PHPs) which are now used extensively in PIM, and micro-reactor technology. These polymers are prepared through the high internal phase emulsion (HIPE) polymerization route. In order to control the pore size, the flow-induced phase inversion phenomenon is applied to the emulsification technique. The metalization of these polymers and formation of nano-structured micro-porous metals for intensified catalysis are also discussed. Finally, we illustrate the applications of these materials in chemical- and bioprocess intensifications and tissue engineering while examining the existence of several size-dependent phenomena. 

Tesfai, A., El-Zahab, B., Bwambok, D.K., Baker, G.A., Fakayode, S.O., Lowry, M., Warner, I.M. Controllable formation of ionic liquid micro- and nanoparticles via a melt-emulsion-quench approach. Nano Lett. 8, 897-901 (2008)... 

Depending on the process conditions, the relative size of the dispersed and emulsion droplets, and the properties of the fuel, the final particles may be either micro or nano-sized and either hollow or solid fully-filled. 

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