Dhr 3 hybrid rheometer

Triborheological profiles of reconstituted mucus under different pH conditions were evaluated in the DHR-3 Hybrid Rheometer (TA Instruments) using a plate-and-plate configuration conformed by a 40 mm diameter stainless steel plate and a Peltier system that acts as a temperature controller (37 °C) during the tests. The coefficient of friction was evaluated by performing a flow sweep test from 0.1 to 50 rad/s, applying a normal force of 1 N.
Additionally, the triborheological performance of the mixture (reconstituted mucus–chitosan:TPP nanoparticles) was measured under the same conditions and compared with reconstituted mucus performance to evaluate the alterations in the coefficient of friction produced by the mucoadhesive interaction.

Rheological measurements were performed on a DHR-3 hybrid rheometer (TA Instruments, Milano, Italy) using a 20 mm aluminum plate-plate geometry. Hydrogel discs were squeezed between the plates and measurements were performed maintaining a constant normal force of 0.3 N. Dynamic Frequency sweeps were performed for all samples applying a strain amplitude ${\gamma }_0=1$ % at oscillation frequencies in the range $0.1\le \omega \le 100$ rad/s.