Figure 3.

Digital switching of cellular uptake by modulation of Arg density was investigated by live cell confocal microscopy. No significant cellular uptake was evident after incubation with Arg₅-ELP_BC (A), ELP_BC (B), or Arg₅-ELP (C) at 37 °C, a temperature at which all constructs existed as soluble unimers. At 42 °C temperature-triggered micelle assembly of Arg₅-ELP_BC increased the local density of Arg on the micelle corona, resulting in enhanced cellular uptake, evident as punctate green intracellular fluorescence (D). This internalized Arg₅-ELP_BC localized to the perinuclear space (D – box). No increase in cellular uptake was observed with the ELP_BC (E) or Arg₅-ELP (F) controls at 42 °C. Green: ELP; Red: cell membrane; Blue: cell nuclei; scale bars 25 μm.