The multi-domain nanoparticle structure of a universal core-multi-shell nanocarrier

Abstract

Nanoparticles with a multi-domain structure have been identified as a new class of highly potent nanocarriers with a dual transport mechanism for polar and non-polar guests. In this paper we present a detailed analysis of their spatial structure, which has been analyzed by small-angle neutron scattering (SANS) including contrast variation. The nanocarriers consist of a hyperbranched polyglycerol (hPG) core onto which di-block segments consisting of non-polar alkyl chains and hydrophilic poly(ethylene glycol) methyl ether (mPEG) has been grafted. The hPG cores have been analyzed separately for comparison. SANS demonstrates that the hPG-cores can be described as fractal structures. The nanocarriers form rather compact structures in the non-polar solvent toluene. A fractal structure with a correspondingly rough surface is found here as well, which is explained by the backfolding of the hydrophilic mPEG-chains in the non-polar environment. In water the nanocarriers associate to form well-defined nanoparticle clusters with an ellipsoidal shape. Contrast variation demonstrates that these particles have no distinct core–shell structure but the separation of the incompatible parts of the structure takes place on a much smaller length scale.