Discovery hybrid rheometer 3 dhr 3

The oscillatory shear measurements of storage modulus of chitosan formulations with and without RA liposomes were measured at room temperature using constant stress rheometer (TA Instruments Discovery Hybrid Rheometer 3 DHR-3) with parallel plates and spindle diameter 12 mm. In brief, 200 μL of chitosan formulation with cross-linker were placed on the lower plate of the rheometer, and the upper plate was lowered to gap size 700 μm immediately. The storage (G′) and loss (G″) moduli were recorded using an amplitude sweep from 0.001% to 10% strain.
Gelation time for the formulations at the different chitosan and cross-linking agent concentrations was recorded based on the time required to form a solid mass for visual observations. Formulations were placed in an Eppendorf tube and agitated in a thermal rocker incubator at various temperatures for required time for the solution solidification. These studies were conducted in triplicates for each formulation and presented as avg. ± std. dev.

A Discovery Hybrid Rheometer-3 (DHR-3, TA Instruments) was used for all
measurements. The temperature was fixed at 37.0 ± 0.1 °C by an
Advanced Peltier Plate. To keep the samples hydrated during the measurement, an
immersion cell (manufactured by TA Instruments) was secured around the bottom
Peltier plate. The bottom and top geometries were both 8 mm crosshatched
parallel plates. A constant gap height of 1600 μm was used for all
experiments; we chose to keep the gap height constant for all samples after
running preliminary experiments at either constant compression or constant gap
height with chicken breast meat (Figure S8 and additional discussion
in the Supplementary
Material). After loading the tissue onto the rheometer, ~40 mL
of PBS preheated to 37.0 °C was added to the immersion cell until the
sample was fully immersed. The axial force at the beginning of the experiment
was between 0.03 and 0.08 N. Samples were first equilibrated at 37.0 °C
for 2 min, and then a frequency sweep experiment was performed (ω =
0.04–40 rad/s). The oscillation strain was selected as 0.5%, which was
within the linear viscoelastic regime of both control and CCH-digested uterine
fibroids. Each sample was measured one time.