Fig. 2: Temperature-dependent DNA localization.
From: DNA storage in thermoresponsive microcapsules for repeated random multiplexed data access
a, Confocal micrographs of DNA-containing proteinosomes after heating to 95 °C and cooling. Here dsDNA (188 bp; A1F1) with Cy5 and biotin labels was localized in DyLight-405-labelled proteinosomes containing either 4 µM streptavidin (top two panels) or Tamavidin 2-HOT (bottom two panels), heated to 95 °C for 5 min, and then cooled to room temperature before imaging. Micrographs of the proteinosome membrane and Cy5-labelled DNA are shown at the top and bottom of each panel, respectively. Only the proteinosomes containing Tamavidin 2-HOT retained dsDNA. Scale bars, 250 µm. Larger versions of these micrographs are shown in Supplementary Fig. 9. The sequences for strands A1 and F1 are provided in Supplementary Table 1. b, Graphic showing temperature-dependent, reversible proteinosome membrane collapse and opening due to PNIPAm chain collapse and swelling, respectively, when conjugated to crosslinked BSA (blue). High (T < LCST) and low (T > LCST) membrane permeabilities are shown as the thin or thick blue dashed circles, respectively. c, Relative fluorescence intensity of fluorophore-labelled DNA inside proteinosomes at room temperature as a function of time. Proteinosomes (n = 21) were confined in a microfluidic trapping array37 to enable simultaneous imaging and reagent addition or removal. A 50-nt-long ssDNA (F2) labelled with Alexa 546 fluorophore was added to the trapping array and diffusion across the membrane was measured using confocal microscopy. After the fluorescent signal stabilized, a buffer was added to remove DNA from the trapping chamber. The solid line indicates the mean signal; the shaded area indicates the standard deviation. The sequence of strand F2 is provided in Supplementary Table 1. d, Relative fluorescence intensity of fluorophore-labelled DNA inside proteinosomes at 95 °C as a function of time. The proteinosomes (n = 15) contained a dsDNA complex (Tm = 65 °C) consisting of 21 nt biotin-labelled DNA strand A2 and 50 nt Alexa-546-labelled strand F2. Proteinosomes were heated to 95 °C and the fluorescence was measured by confocal microscopy. The solid line indicates the mean signal; the shaded area indicates the standard deviation. The sequences for strands A2 and F2 are provided in Supplementary Table 1.
