Co-assembly of two types of complementary dendritic units into amphiphilic supramolecular complexes capable of hosting guest molecules

Abstract

A new supramolecular complex, which can be used as a nanocarrier, was formed conveniently by the co-assembly of hyperbranched polyethylenimine (HPEI) with a novel carboxylic acid which has one or two generations of dendrites. The obtained supramolecular complexes consisting of two different dendritic polymeric segments were verified by FTIR, ¹H NMR and DLS. After extracting with water or solutions of dyes, the supramolecules can form large aggregates as verified by DLS analysis. These supramolecular aggregates could be used as nanocarriers to efficiently encapsulate polar dyes such as the anionic dyes methyl orange (MO), eosin Y (EY) and fluorescein sodium (FS). This encapsulation behavior of the complexes based on an aggregation mechanism is different from that of the simple inverted micelles and unimolecular transporter systems reported. And the encapsulation capacities of the aggregates could reach a maximal value as the HPEI concentration and the density of the carbon chains increased to a certain value. Besides, the carrier with a dendritic shell could accommodate more guests than the corresponding carriers with only a linear shell, which shows the superiority of the dendritic shell. Meanwhile, an increase of the length of the outer carbon chain in the complex could distinctly improve the encapsulation ability. Therefore, supermolecules with a dendritic shell not only simplify the synthesis approach of covalent polymers, but also maintain a high encapsulation ability for guests, which are attributes worth popularizing.