Soft matter nanoparticles with various shapes and functionalities can form through electrostatic self-assembly

Electrostatic self-assembly is an important area presenting fascinating opportunities for the design of functional and responsive nanostructures. In this contribution we highlight a recent approach that allows the formation of nanoscale assemblies with a variety of shapes - spheres, rods, hollow spheres, networks and rings - from macroions and multivalent organic counterions as building blocks. Combination of electrostatics and secondary forces is key to a directed structure formation, while the charged nature of the assembled nanoparticles gives rise to their stability in solution. The concept allows the formation of nanoassemblies which respond to external stimuli. Macroionic building blocks can range from linear polyelectrolytes over ionic dendrimers to cylindrical polyelectrolyte brushes, and counterions can be ionic dye molecules, porphyrins or other stiff or semiflexible ions. The versatility and potential of the strategy are discussed.