Multicompartment Nanoparticles Bearing Hydrophilic/Hydrophobic Subdomains by Self-Assembly of Star Polymers in Aqueous Solution
Haohui Huo, Jie Liu, Senthil Kannan, Long Chen, Yimin Zhao, Lei Zhang, Gang Chang, Qilu Zhang, Feng Liu
Abstract
The direct construction of protein-like multicompartment nanoparticles (MCNs) possessing hydrophilic/hydrophobic subdomains is a contemporary challenge. Herein, we present the first example of such MCNs via self-assembly of the specially designed A(BC)20 star polymer in an aqueous solution. The topology of the 21-arm star polymer, poly(ethylene glycol)[poly(acrylic acid)-block-polystyrene]20 [PEG(PAA-b-PS)20], is the key to simultaneously form hydrophilic/hydrophobic subdomains of nanoparticles during self-assembling, as the water-soluble PAA blocks are confined in the core, resulting in hydrophilic subdomains. The volume ratio of PS to PAA (VPS/VPAA) is found to be the main factor that determines the morphology of MCNs; besides micelles and vesicles, strings consisting of one-dimensional (1D) alignment of single-star polymers were found for the first time, as confirmed by transmission electron microscopy (TEM) and cryo-TEM. Lastly, a new mechanism for the assembly of the star polymers was proposed based on the investigations of PEG(PAA-b-PS)20 self-assembly under different water contents, concentrations, and pH values. The MCNs reported in this work may find various applications in, e.g., co-delivery of drugs and heterogeneous catalysis.