Rhodamine conjugated poly 1 c

Alexa Fluor 647 conjugated
OVA (Thermo
Fisher Scientific), rhodamine conjugated Poly(I:C) (Invivogen), and
rhodamine conjugated HPMC–C₁₂ were used to visualize
the diffusion of the cargo and gel. Samples were photobleached with
a 50 μm diameter for the region of interest (ROI). Different
tests (n = 5) were made for three different samples
from the same batch at different locations of the sample. A spot was
bleached with a pixel dwell time of 177.32 μs. A total of 500
postbleach frames were recorded at 1 frame/s to form the recovery
exponential curve. The diffusion coefficient was calculated as^{70 (link)} where the constant γ_D = τ_1/2/τ_D, with τ_1/2 being the half-time of the
recovery, τ_D being the characteristic
diffusion time,
both yielded by the ZEN software, and ω being the radius of
the bleached ROI (25 μm).
The diffusivity of cargo in
PBS was calculated using the Stokes–Einstein law equation for
diffusion⁷¹ where k_B is Boltzmann’s constant, T is temperature
in Kelvin, η is solvent viscosity, and R is
the solute hydrodynamic radius The diffusivity of cargo in a model covalent
PEG gel was calculated using the multiscale diffusion model (MSDM)
assuming 25 °C, a 5% volume fraction, and 35 nm mesh size.^{72 (link)} The calculated values are comparable to experiment
diffusivities of similar sized cargoes found in the literature.^{73 (link)}