Study on preparation and formation mechanism of n-alkanol/water emulsion using alpha-cyclodextrin

Chem Pharm Bull (Tokyo). 2007 Nov;55(11):1620-5. doi: 10.1248/cpb.55.1620.

Abstract

Surfactants are usually used for the preparation of emulsions; however, some have an adverse effect on the human body such as skin irritation, hemolysis, and protein denaturation, etc. In this study, we examined the preparation and formation mechanism of n-alkanol/water emulsions using alpha-cyclodextrin (alpha-CD) as an emulsifier. Emulsions were prepared by mixing oil and water phases for 4 min at 2500 rpm using a vortex mixer. The mechanism of emulsification was investigated with some physico-chemical techniques. From phase diagrams of n-alkanol/alpha-CD/water systems, the emulsion phase extended as the chain length of n-alkanols and the amount of alpha-CD added increased. Furthermore, the emulsion was not formed in the region where the n-alkanol/alpha-CD complex didn't precipitate; however, the emulsion was formed in the region where the complex precipitated. In addition, it was clear that the emulsions have a yield stress value and correspond to the Maxwell model from rheological measurement. Our experiments clearly showed that the stable emulsions are formed because the precipitated complexes form a dense film at the oil-water interface and prevent aggregation among dispersed phases. Furthermore, it is suggested that the creation of a three-dimensional network structure formed by precipitated complexes in the continuous phase contributes to the stabilization of the emulsion. Thus, we concluded that the n-alkanol/water emulsions using alpha-cyclodextrin were a kind of the Pickering emulsion.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alcohols / chemistry*
  • Chemistry, Pharmaceutical / methods*
  • Emulsifying Agents / chemistry*
  • Microscopy, Polarization
  • Oils / chemistry*
  • Rheology
  • Solubility
  • Stress, Mechanical
  • Water / chemistry*
  • X-Ray Diffraction
  • alpha-Cyclodextrins / chemistry*

Substances

  • Alcohols
  • Emulsifying Agents
  • Oils
  • alpha-Cyclodextrins
  • Water