Entropy-driven segregation and budding in hybrid vesicles of binary nanoparticle amphiphiles

Abstract

Self-assembly of giant building blocks beyond conventional molecules offers tremendous opportunities for the fabrication of new-generation structural materials. This work describes the macroscopic colloidal segregation in the vesicular self-assembly of binary nanoparticle amphiphiles (NPAMs) consisting of block copolymer-grafted nanoparticles in solution. Depending on their relative size and concentration, binary NPAMs with distinctive sizes assemble into hybrid vesicles with different morphologies, namely, homogeneous vesicles, patchy vesicles, and yolk/shell vesicles. The segregation of NPAMs confined within or escaped from the vesicular membrane is driven by the conformational entropy gain of end-grafted copolymer ligands. The effect of NPAM size and concentration on the morphological transition of vesicles is mapped in a phase diagram. Moreover, a vesicular fusion/budding mechanism is proposed to illustrate the formation of uniform vesicles with yolks inside. The hybrid vesicles have potential applications in cancer imaging, biosensing, and drug delivery.

Keywords

• Self-assembly
• Polymer ligands
• Gold nanoparticles
• Vesicles
• Segregation