Charge emulsion

Figure 13. Simplified illustration of the surface and zeta potentials for a charged emulsion droplet dispersed in high and low electrolyte concentration aqueous solutions. (Courtesy of L. A. Ravina, Zeta-Meter, Inc., Long Island...

An electric field applied to a nozzle results in a jetting phenomenon and the formation of an electrically charged emulsion of micron-sized droplets. This method may lead to a 200-500-fold increase in the surface area per unit volume, compared to the millimeter-sized droplets obtained in the conventional process. 

When an emulsion formulation is administered into the bloodstream it comes into contact with positively charged electrolytes (e.g., sodium or calcium ions) that might cause a reduction in surface charge and can even display a charge reversal (14). While there is evidence that such systems behave satisfactorily, it can be suggested that charged emulsions could behave differently when intro-... 

Posilively charged emulsions were shown to have an affinity for corneal surfaces, binding for sufficient periods to optimize the release of the encapsulated drug. Wehrle et al. (121) confirmed the importance of positive charge on corneal retention of emulsions presumably as a result of association with the polyanionic corneal and conjunctival mucoglycoproteins. 

Figure 7 Dimensionless d.c. mobility as a function of dimensionless potential according to the numerical calculations of O Brien and White (33) for the value of ka relevant to the highly charged emulsion system (see text).

Electrostatic double-layer forces are always present between charged particles or emulsion droplets in electrolyte solutions. Counterions to the emulsion droplet (ions with opposite charges to that of the drop) are attracted to the surfaces and coions are repelled. Hence, outside the charged emulsion droplet, in the so-called diffuse layer, the concentration of ions will be different to that in bulk solution, and the charge in the diffuse layer balances the surface charge. 

Beattie, J.K., DJerdJev, A.M. The pristine oil/water interface surfactant-free hydroxide-charged emulsions. Angew. Chem. Int. Ed. Engl. 43, 3568-3571 (2004)... 

HastweU, P. J. Kaethner, T. M. Charged emulsions for site-specific micrometer and nanometer scale deposition and applications in the manufacture of DNA chips. PCT Int. Appl. WO 2005000970, 2005 Chem. Abstr. 2005,142,108364. 

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