Controlling the number of dendrimers in dendrimicelle nanoconjugates from 1 to more than 100

Abstract

Herein, we present a facile strategy to controllably build up dendrimicelles by self-assembly of anionic PAMAM dendrimers with cationic–neutral diblock copolymers. We present a systematic study incorporating a full decade (0–9) of dendrimer generations, tracing the gradual variation from aggregates (G0 and G1) to self-assembled micelles (G2–G8), and an unidendrimer micelle structure (G9) by different scattering techniques (light and X-ray). The formed micelles (G2–G9) are spherical in shape with a hydrodynamic radius of about 25 nm. Interestingly, the micellar size, structure and number of incorporated block copolymers are independent of the dendrimer generation (for G2 to G9), while the aggregation number of the dendrimers decreases from 108 to 1, and the stability of the micelles increases upon an increase in the dendrimer generation. Moreover, the micelles with lower generation dendrimers transform from spherical into worm-like structures upon an increase in the positive charge fraction (excess polymers) or ionic strength, while micelles with higher generation dendrimers do not show such a transition. This differential behavior is in-line with a change from a flexible configuration into rigid globular nanoparticles with increasing dendrimer generation. The reported systematic investigation of dendrimicelles comprising a full decade of dendrimer generations provides the basis for versatile strategies focused on building up new (multi)functional materials, e.g. by packing multiple types of dendrimers with different functional groups or encapsulated cargos controllably within one micelle.