Figure 6.

AFM images in PBS buffer of photopatterned dextran on (a, b, c) polyurethane (PU) and (e, f, g) polystyrene (PS): (a, d) topography, (b, e) line scan across white line in (a) and (c, f) 3D topographic image of 70×70 μm² scan size (z scale: 20 nm) and 80×80 μm² scan size (z scale: 20 nm) for PU and PS, respectively. On PU in PBS, the irregular dextran features observed in air (h ≤ 20 nm) swell and turn into flatter and more uniform features (h ≤ 5 nm). Although the PU regions (OX-PU) remain predominantly flat in PBS, the PU regions also display some features due to swelling of arbitrary dextran chains. In constrast, on PS in PBS, the dextran region (DEX-PS) swell by 3x its dried thickness from 1.3 ± 0.4 nm to 3.8 ± 1 nm. Similar to the dried sample, the surface is smooth as previouly noted in Figure 4. The PS regions (OX-PS) also remain predominantly flat in PBS but display some features due to swelling of residual dextran molecules.