Bottom: particle aggregation after pH decrease tracked by measuring the hydrodynamic radius of growing aggregates with differential dynamic microscopy (DDM, left axis)[62,63]and the normalized epifluorescence intensity of accumulating CMs labeled with Alexa Fluor 594 (red, right axis). Triangles and squares represent responsive particles incubated at pH 7.0 (triangles) and 4.5 (squares). Circles indicate a control sample with nonresponsive particles at pH 4.5, where theIMandIM*-3mdomains have been replaced with non-responsive sequences. Data are plotted as mean standard error (shaded regions) of three (circles and triangles) or six (squares) measurements conducted on two independently prepared samples. Top: epifluorescence microscopy images of responsive particles after pH decrease at different time points (t= 0, 150, and 600 min). See FigureS5, Supporting Information for additional microscopy images.
