Preparation and characterization of nanoparticles made from amphiphilic mono and per-aminoalkyl-β-cyclodextrins

Abstract

Abstract Aminoalkyl derivatives of β-cyclodextrin, in their neutral form are insoluble amphiphilic cyclodextrins that could be dispersed as nanoparticles in water. Such nanoparticles solubilize host molecules either in the non-polar medium in between the alkyl chains or in an environment of medium polarity inside the hydrophobic cavity of the cyclodextrins. This allows the solubilization of a wider range of molecules such as drugs, fragrances, aromas… than classical nanoparticles containing either oil or polymer. A series of such compounds either mono- or per-substituted at the C6 methylene of the β-CD primary rim with either short butyl chain or long dodecyl chain are obtained by chemical modification of native β-cyclodextrin with aminoalkyl groups. Their physicochemical properties and utilization for the manufacture of nanoparticles have been studied. The solubility assessed from direct microscopy observation and surface tension measurements were low; they were related to the hydrophobic character of the amphiphilic β-CDs, that is, the number and length of their alkyl chains. The monobutyl derivative adsorbs at the air–water interface as a monolayer whereas the most hydrophobic derivatives collapses into a 3-dimensional adsorbed layer. Stable nanoparticles were prepared by means of dispersion by ultrasound or by the nanoprecipitation method. Sonication yielded large and polydisperse nanoparticles of size larger than 500 nm; nanoprecipitation resulted in the formation of small nanoparticles with sizes in the range 100–200 nm with a narrow particle size distributions.