Figure 4.

Characterization of the morphology of the FAME aggregates and visualization of their temperature-triggered phase transition and self-assembly across different length scales and temperatures. a-c, Cryo-TEM of the FAMEs dissolved in PBS at 20 °C (T < T_t): M-B₁-ELP (a), M-B₂-ELP (b), and M-B₃-ELP (c), showing cylindrical micelle morphology with an average length increasing with the β-sheet-formation propensity of the PA-domain. d-f, SFM topography of the FAMEs, drop cast from solution at 30 °C (T_c > T > T_t): M-B₁-ELP (d), M-B₂-ELP (e), and M-B₃-ELP (f), showing that FAME nano-aggregates are rod-like polymeric micelles and fibers. g-l, M-B₁-ELP transitions into liquid coacervates at 30 °C (g) that remain stable up to 50 °C (j) but reach a larger equilibrium volume. M-B₂-ELP transitions into a network of fibers above T_t (h). At higher temperatures (T > T_c), these fibers form a stable interconnected network of fibers (k). Above T_t, M-B₃-ELP forms a “beads-on-a-string” morphology that is likely due to the arrested coalescence of the initial liquid coacervates (i). Above T_c, these droplets form fractal-like amorphous aggregates (l). The inset in k and l provide a higher magnification obtained using the super-resolution mode of the microscope.