2.2.6 Rheology
Rheological properties were measured using a Kinexus Ultra + rheometer (Malvern Panalytical, UK). For the determination of the shear viscosity and viscoelastic properties (G’), we used a plate geometry of 20 mm diameter, a gap of 0.5 mm and the temperature was kept constant at 37°C. Shear viscosity measurement were carried out with a shear rate ranging from 10-1 to 103s-1. Gelatin and Gel-PDA-PAR30 1:1 (non-diluted) were prepared as previously described without microbial-TGA and then 200µL of these solutions were put in the rheometer at 37°C. Viscoelastic properties measurement were performed with a frequency ranging from 0.1 to 50 Hz at a fixed strain of 0.5%. For this experiment, microbial-Transglutaminase was added to Gelatin and Gel-PDA-PAR30 solutions at a ratio 1:5 and then 200µL of these solutions were put in the rheometer at 37° C and let crosslinked overnight before performing the sweep frequency experiment.