FIGURE 3.

Fluorescence recovery after photobleaching experiments characterize 2:10 hydrogel mesh size. FRAP experiments were performed on the 2:10 formulation hydrogel using multiple sizes of FITC‐Dex as fluorescent cargo: (i) 4 kDa, R_H = 14 Å, (ii) 40 kDa, R_H = 45 Å, (iii) 70 kDa, R_H = 60 Å, and (iv) 250 kDa, R_H = 120 Å. (a) A defined circular region of each gel is bleached via exposure to intense light and passive diffusion of dye‐conjugated molecules into the region causes local fluorescence recovery. (b) Fluorescence recovery over time generates a curve from which the diffusivity of the fluorescent components can be calculated. (c) The gel network causes significantly slowed cargo diffusion compared with the diffusivities of FITC‐Dex in PBS (calculated with the Stokes‐Einstein equation). (d) Comparison of the FITC‐Dex diffusivity values with the diffusivity of the polymer matrix (taken as the diffusivity of the HPMC‐C₁₂ component, D_matrix = 0.68 ± 0.11 μm²/sec) shows that cargo diffusion decreases with increasing cargo size, reaching a plateau at a hydrodynamic radius of around 60 Å, after which entrapped cargoes diffuse at similar rates