Fig. 3.

In vitro antibody release and diffusivity from the PNP hydrogel for two different hydrogel formulations. The selected antibody was fluorescently-labeled rat IgG. a) Characteristic recovery time τ correlates with burst release versus retention of antibody cargo. b) Percent of antibody released 5 minutes post-injection into a PBS-filled microcentrifuge tube (mean ± SD, n=3); p-value determined by two-sided unpaired t-test. c) Cumulative in vitro release of antibody from a PNP hydrogel (mean ± SD, n=5); trendline shown is a Ritger-Peppas empirical fit.⁵¹ d) Diffusivity (D_IgG) of free antibody compared to gel-encapsulated antibody as quantified by dynamic light scattering (DLS, PBS sample) and fluorescence recovery after photobleaching (FRAP, hydrogel samples) (mean ± SD, n=5 for PBS, n=3 for hydrogels). Statistical significance was determined by one-way ANOVA (F (DFn, DFd) = F (2, 8) = 82.62). Tukey post-hoc tests were applied to account for multiple comparisons. e) Ratio of antibody diffusivity to hydrogel diffusivity (D_gel), where D_gel is the diffusivity of fluorescently-labeled HPMC-C₁₂ within the denoted hydrogel formulation as measured by FRAP (mean ± SD, n=3). f) Illustration of possible antibody diffusion process where passive diffusion of the antibody is limited by the dynamic mesh of the hydrogel network.