Nanoemulsion types

Hatanaka et al. (2008) examined a number of different types of encapsulation systems for coenzyme Qio- Systems examined included a novel liquid nanoemulsion and water-soluble powder formulations, acyclodextrin inclusion complex, and a dry emulsion. Of the delivery systems examined the novel nanoemulsion delivery system, which had the smallest particle size (60 nm) compared to the other delivery systems examined (770-2400 nm), had the highest bioavailability when tested in rat models (Hatanaka et al., 2008). 

Wooster, T. J., Golding, M., and Sanguansri, P. (2008). Impact of oil type on nanoemulsion formation and Ostwald ripening stability. Langmuir 24, 12758-12765. 

It is useful, for reasons which are apparent in relation to movement of nanoparticles in vivo, to divide nanosystems into two types, hard and soft, although there are obviously intermediate situations. Hard systems, for example, polymeric nanoparticles and nanocapsules, nanosuspensions or nanocrystals, dendrimers, and carbon nanotubes are neither flexible nor elastic. Hard systems can block capillaries and fenestrae that have dimensions similar to the particles, whereas soft systems can deform and reform to varying degrees. Erythrocytes and many liposomes fall into this category and are thus better able to navigate capillary beds and tissue extracellular spaces. Soft systems include nanoemulsions (microemulsions) and polymeric micelles. 

In spite of the above difficulties, several companies have introduced nanoemulsions onto the market, and their benefits will be evaluated within the next few years. Nanoemulsions have been used in the pharmaceutical industry as drug-delivery systems [5], although the acceptance by customers of nanoemulsions as a new type of formulation depends on how they are perceived and their efficacy. With the advent of new instruments for high-pressure homogenisation, and the competition between various manufacturers, the cost of nanoemulsion production wiU surely and may even approach that of classic macroemulsions. Fundamental investigations into the role of surfactants in the process [6,7] will lead to optimised emulsifier systems such that a more economic use of surfactants will doubtless emerge. 

Nanoemulsions can be prepared starting from microemulsions located in the inverse microemulsion domain, Oj, and in the direct microemulsion domain, W, at different oil surfactant ratios ranging from 12 88 to 40 60, and coincident for both types of microemulsion. The water concentration is fixed at 20% for microemulsions in the domain labelled as O l, 0 2, 0 3, 0 4, and 0 5. The microemulsions in the region are accordingly W 2, W 3, W 4, and W 5, and their water content was decreased from W 2 to W 5. 

An emulsion is a significantly stable suspension of particles of liquid of a certain size within a second, immiscible liquid. The term significantly stable means relative to the intended use and may range from a few minutes to a few years. Investigators in this field distinguish between three different types of emulsions, based upon the size of the dispersed particles (1) macroemulsions, the most well-known type, opaque emulsions with particles >400 nm (0.4 pm), easily visible under a microscope (2) microemulsions, transparent dispersions with particles <100 nm (0.1 pm) in size and (3) nanoemulsions (miniemulsions), a type that is blue-white, with particle sizes between those of the first two types (100-400 nm [0.1-0.4 pm]. Multiple emulsions (Matsumoto, 1976), in which the dispersed particles are themselves emulsions, have been the subject of considerable investigation. 

Molecular inclusion or conjugation complexes, micelles, microemulsions, polymeric particles, and emulsions and nanoemulsions can all be classified as matrix type encapsulation systems. 

Donsi, R Sessa, M. Rerrari, G., Effect of emulsifier type and disruption chamber geometry on the fabrication of food nanoemulsions by high pressure homogenization. Industrial and Engineering Chemistry Research (2012) 51, 7606-7618. 

Three types of nanoemulsion are formed depending upon the composition. 

In all of the above types of nanoemulsion, the interface becomes stable by addition of suitable blend of surfactants or cosurfactants (Tables 13.3 and 13.4). 

Chausson, M., Fluchere, A.S., Landreau, E., Aguni, Y., Chevalier, Y., Hamaide, T., Abdul-Malak, N., Bonnet, 1. (2008) Block copolymers of the type poly (caprolactone)-b-poly (ethylene oxide) for the preparation and stabilization of nanoemulsions. Int. J. Pharm.,362,153-162. 

T. Hagigit, T. Nassar, R Behar-Cohen, G. Lambert and S. Benita, The influence of cationic lipid type on in-vitro release kinetic profiles of antisense oligonucleotide from cationic nanoemulsions. Eur. ]. Pharm. Biopharm., 70, 248-259 (2008). 

Nanoparticles in skincare products include various types of dehvery systems and can be subdivided on the basis of the encapsulating membrane structure into hposomes, nanoemulsions, nanosomes, and nanotopes. They can carry many actives to penetrate into skin quickly and into intracellular structures while conventional skincare products usually do not penetrate the skin and release the active by diffusion or by capsule destruction. Nanoparticles also bring up many other new applications. For example, skin whitening or Kghtening is a more recent apphcation in which actives carried by nanoparticles penetrate beyond the skin barrier, and more active reaches the necessary site of action in the skin, resulting in improved performance. 

These surfactants have many uses, in particular as colloid and nanoemulsion dispersants, wetting agents, detergents and even additive to dehydrate crude oils. However, most polymeric surfactants are graft-type, particularly synthetic products such as polyelectrolytes, which are not strictly surfactants or are not used for their surfactant properties. It is the case of hydrosoluble or hydrodispersible polyelectrolytes which are utilized for the antiredeposition, dispersant and viscosity-enhancing properties such as carboxymethyl cellulose, polyacrylic acid and derivatives. 

Due to their smaller globule size and large surface area, nanoemulsions will easily absorb into the skin, so they should not have any type of virulent or irritant effects on the skin membranes. These formulations are also capable of transferring plant constituents to cell culture for treatment of cancer [48]. The drug delivery of curcumin by microemulsion increased its absorption as compared to simple curcumin emulsion [49]. For increasing the solubility and absorption of ubiquinone, a nanoemulsion of ubiquinone was also developed [50]. 

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