Figure 3.

Actinosomes are porous and permeable to small molecules. (a) Diameter of gyration (D_g) of dextran molecules as a function of their molecular weights (M). The red line follows the equation D_g = 2.64 × M^0.33. (b) Confocal images showing the permeability of actinosomes (R = 0.7) to dextran molecules of different sizes, immediately (t₀) and 1 h (t₆₀) after incubation. Low-molecular-weight dextran (3–5 kDa) readily diffuses inside actinosomes, whereas high-molecular-weight dextran (20 kDa) is excluded from the actinosome. (c) Graph showing the normalized intensity (I_inside – I_outside)/I_outside of FITC-dextran at t₀ (red) and t₆₀ (blue). Positive values indicate dextran diffusion into the actinosomes, while negative values indicate impermeability to dextran. Error bars indicate standard deviations. (d) Scanning electron microscopy images of actinosomes (R = 0.7) appear as slightly crumpled spheres, similar to fluorescence images. (e) A zoom-in reveals a rough, unstructured, porous surface. Several sub-μm-sized pores are clearly visible and indicated with arrows. Error bars indicate standard deviations.