Fig. 5. Redox-induced intracellular self-assembly.

a | Glutathione-induced cleavage of a disulfide bond changes the lower critical solution temperature (LCST) behaviour of a polymer conjugate, causing it to form intracellular nanoaggregates⁵⁸. Bio-transmission electron microscopy of MC7 cells shows the presence of intracellular nanoparticle. b | Cleavage of a reactive oxygen species (ROS)-sensitive thioketal group induces fibre formation¹⁴. Transmission electron microscopy images show ROS-induced transformation from nanoparticles to nanofibres in hydrogen-peroxide-containing phosphate buffer. KLAK, mitochondria-targeting peptide; P₁₈, purpurin 18; PNIPAm, poly(N-isopropylacrylamide); PVA, polyvinyl alcohol. Part a (right) is adapted with permission from ref.⁵⁸, American Chemical Society. Part b (bottom left and right) is adapted with permission from ref.¹⁴, American Chemical Society.