## 3 Results
### Hydrogels Reduce the Permeation of Sodium Flourescein and Rhinovirus 14
The two-hour incubation period of the samples served to test whether a one-hour to two-hour virus adsorption time is feasible in the plaque  
Figure 5: Cumulative diffusion of 20 \(\upmu\)g sodium fluorescein across a mixed cellulose ester membrane covered with hydrogel samples or artificial saliva (300 \(\upmu\)L) over 6 h, \(\bullet\) artificial saliva, \(\triangle\) 0.35% xanthan gum, \(-\) 0.65% sodium hyaluronate. Mean \(\pm\) standard deviation. Each sample was measured in triplicate. assay without having any effects on the cells and the monolayer. All tested substances show acceptable viability within the system. After a 2-h incubation with isla Conc. 1 (0.23 g lozenge/mL), the H1-HeLa cells show a viability of 71.0% \(\pm\) 6.2%. The average viabilities of the H1-HeLa cells incubated with 0.115 g lozenge/mL (isla Conc. 2) and 0.077 g lozenge/mL (isla Conc. 3) were 92.9% \(\pm\) 1.0% and 96.6% \(\pm\) 3.3%, respectively. Therefore, the plaque assay to determine the preventive function of the hydrogels on rhinovirus infections was carried out with 0.115 g lozenge/mL and 0.077 g lozenge/mL. The two-hour incubation with two of the main components of the hydrogel complex contained in isla(r) medic, xanthan gum, and sodium hyaluronate, resulted in relative cell viabilities of 101.5% \(\pm\) 1.5% (xanthan gum) and 93.7% \(\pm\) 4.9% (sodium hyaluronate), which indicates that the hydrogels can also be used in the preventive plaque assay. To determine the effect of the hydrogels in terms of preventing rhinovirus infections in vitro, the physical barrier function was tested in a plaque assay with RV-14. H1-HeLa monolayers were covered with isla Conc. 2 (0.115 g lozenge/mL) or isla Conc. 3 (0.077 g lozenge/mL) and RV-14 was applied onto the hydrogels. As shown in Figure 6, the monolayers covered with the hydrogels have fewer plaques than the untreated control. In total, in all three independent experiments, significantly fewer plaques were formed in the cell monolayers covered with isla Conc. 2 and isla Conc. 3. With regard to the untreated control, isla Conc. 2 (0.115 g lozenge/mL) reduces plaque formation by a mean of 61.7% \(\pm\) 14.7% and isla Conc. 3 by 49.3% \(\pm\) 12.5% (Figure 7). Taking into account the standard deviation, no concentration-dependent effect can be determined. Figure 6: Preventive plaque assay – H1-HeLa cell monolayer with plaques dyed with crystal violet: (**a**) untreated control, RV-14 was applied directly onto the cells, (**b**) isla Conc. 2 (0.115 g lozenge/mL), applied before RV-14, (**c**) isla Conc. 3 (0.077 g lozenge/mL), applied before RV-14. Figure 7: Results of the preventive plaque assay—Counted plaques on H1-HeLa cell monolayers of the untreated control (white) and cells treated with isla Conc. 2 (light grey) and Conc. 3 (dark grey), mean \(\pm\) standard deviation of the independent test runs with three repetitions, \({}^{*}\)\(p\)\(\leq\) 0.05. Figure 8 shows the results of the preventive plaque assay carried out with 0.35% xanthan gum or 0.65% sodium hyaluronate. Even the individual components of the hydrogel complex contained in isla(r) medic, such as xanthan gum, reduces plaque formation significantly by 85.1% \(\pm\) 4.3% and sodium hyaluronate by 89.0% \(\pm\) 3.1%. A curative plaque assay was performed to investigate whether the hydrogel complex not only has a preventive protective function but also a curative effect on an existing rhinovirus infection. After infection of the cells, an overlay medium was applied for 72 h to which isla Conc. 3 was added in different amounts. To determine the ideal amount of the product for the curative plaque assay, the cell viability was examined after a 72-h incubation time with different proportions of isla Conc. 3 (20%, 30%, 40%, and 50%) in the overlay medium. The average cell viabilities of the H1-HeLa cells incubated with 20%, 30%, 40%, and 50% isla Conc. 3 (0.077 g lozenge/mL) for 72 h were 83.4% \(\pm\) 2.7%, 76.7% \(\pm\) 3.3%, 70.3% \(\pm\) 3.7%, and 56.5% \(\pm\) 2.7%, respectively.