Light-responsive self-assembled microstructures of branched polyethyleneimine at low pH.

Soft materials comprising polyethyleneimine (PEI), which integrate low pH-stimulated higher-order assemblies (fibres and sheets) with light responsiveness, have been shown. Excitation wavelength light-driven interactions enable the formation of bead-necklace-type structures in fibres or volume collapse of sheets. This work can have significant implications for transfection or encapsulation through PEI-based complexes.