Fig. 4: Selective permeation of CPCs.

a A microscope-compatible, permeability device with a lower chamber, a CPC membrane, and an upper chamber. b A scheme showing the guest molecules in the feed phase tend to traverse the COA10@POR2 to reach the receiving phase. c False-color, fluorescence images to indicate the disfavored partitioning of PEG-20K (MW ~ 20 K, 0.04 g L^–1), PEG-5K (MW ~ 5 K, 0.04 g L^–1), BSA (MW ~ 65 K, 5 μM), RhB (MW = 479, 5 μM), and ε-PL (MW ~ 5 K, 0.01 g L^–1) into the COA10 droplets (4 g/L, 0.2 M NaCl, pH = 7.2). Two PEGs are tagged by HEMA-RhB, BSA by TRITC, and ε-PL by FITC. d Permeation of BSA across the COA10@POR2 membrane following a concentration gradient from the lower to the upper chambers. e The decay of normalized fluorescence intensity in the feeding phase for five different guests (dots) is fitted by an exponential function (lines) to give the rate constant (R). f Transport rate relative to that across bare pores (R/R₀) is plotted against the K values, where a liner fitting can reasonably match the data (black line). Data are presented as mean ± SD (n = 3 independent experiments). The blue, cyan, green, orange, and red in (e, f) correspond to PEG-20K, PEG-5K, BSA, RhB, and ε-PL as the guest molecules, respectively. Scale bars = 30 μm (c) and 5 μm (d).