Oil-in-Water Nanosized Emulsions for Drug Delivery and Targeting. Tamilvanan Shunmugaperumal. Читать онлайн. Newlib. NEWLIB.NET

Автор: Tamilvanan Shunmugaperumal
Издательство: John Wiley & Sons Limited
Серия:
Жанр произведения: Химия
Год издания: 0
isbn: 9781119585251
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(w/w)] along with an alkanol component. But the kinetically stable nanosized emulsions can be prepared by using relatively lower surfactant concentrations. For example, a 20% o/w nanosized emulsion may only require a surfactant concentration of 1–5%. The kinetic stability of the nanosized emulsions can be achieved by creating a barrier at the oil–water interface, protecting the emulsion from breakage (Capek 2004). These barriers may be of electrostatic or steric nature and prevent emulsion droplets from direct contact. The most common way to stabilize emulsions is by surfactant adsorbed at the interface between the dispersed oil droplets and continuous aqueous dispersion medium. Surfactant adsorption layers do not only reduce the interfacial tension but can also provide an electrical charge to the emulsion droplets (ionic surfactants) or create the strong steric barrier via bulky molecular groups directed toward the dispersion medium (nonionic surfactants).

Photo depicts freeze-dried emulsions using different cryo- or lyo-protectants and reconstitution of freeze-dried powder into nanosized emulsion.

      It is known from the literatures that the interaction between cationic liposomes and polyanionic macromolecules like DNA is dependent on ± ratio, and at the ratio of maximum transfection there is a major aggregation leading to destabilization of formulation or desorption of DNA from the formulation (Liu et al. 1997). Furthermore, Simberg et al. (2003) suggest that an understanding of the interplay between lipoplex composition, its interaction with serum, hemodynamics, and target tissue properties (susceptibility to transfection) could explain the biodistribution and efficient in vivo transfection following intravenous administration of cationic lipid‐DNA complexes (lipoplexes) into mouse. However, it is interesting to see what could happen when the cationic nanosized emulsion is applied to in vitro cell culture models in the presence of serum. The serum stability of emulsion/DNA complex was reported (Yi et al. 2000). Further studies are, however, necessary to be carried out to understand clearly the origin of the serum stability of this emulsion. In addition, the transfection efficiency of this emulsion was not affected by time up to 2 h post‐emulsion/DNA complex formation. This means that the o/w cationic nanosized emulsion allows the experimenter to have a wider time window to work within during transfection study.

      The o/w nanosized emulsions stabilized by both cationic and anionic lipidic emulsifiers were investigated in order to compare the degree of binding and uptake by specific cells that over‐expressed tumor receptors (Goldstein et al. 2007a). Immunoemulsions were prepared by conjugating an antibody to the surfactant molecule via a hydrophobic linker and then the antibody‐conjugated surfactant was used to make the emulsion by the de novo method. The anionic stabilized emulsions showed decreased stability leading to phase separation after 20 days of storage. The reduced stability of anionic immunoemulsion could be attributed to the rapid decrease of