*4.4. Determination of Encapsulation Efficiency and Loading Capacity of Quercetin/HP-β-CD Inclusion Complex*

The drug-loading process was carried out through a diffusional mechanism, and the encapsulation efficiency (%EE) was used to illustrate the quantity of added drug encapsulated in the formulation. The amount of encapsulated quercetin was determined using a direct method [18] and recorded on a calibration curve at 379 nm.

Briefly, 20 mg of quercetin/HP-β-CD inclusion complex was dissolved in 20 mL DMSO. The amount of quercetin was quantified using a UV-Vis spectrophotometer at a wavelength that provided the maximum absorbance (379 nm), and the concentration was back-calculated from the predetermined quercetin calibration curve. Encapsulation efficiency (%EE) and loading capacity (%LC) were calculated from the following equations [47]:

$$\text{EE}\left(\%\right) = \frac{\text{W}\_{\text{Entropyped Quercetin}}}{\text{W}\_{\text{Quercetin loaded}}} \times 100\tag{1}$$

$$\text{LCC} \left( \% \right) = \frac{\text{W}\_{\text{Entropyped Queccein}}}{\text{W}\_{\text{Sample}}} \times 100 \tag{2}$$

## *4.5. Preparation of Quercetin/HP-β-CD Inclusion Complex-Loaded Hydrogels*

Quercetin/HP-β-CD inclusion complex was loaded into 10% *w/v* PVA hydrogels. Briefly, 2 g of PVA was slowly dissolved in 20 mL distilled water at 80–100 ◦C for 40 min.

Then, an accurate weight of quercetin/HP-β-CD inclusion complex was added to PVA solutions at concentrations of 0, 0.5, 1.0, 1.5, 2.5, and 5.0% *w/v*, which were labeled as conditions PVAIC0, PVAIC0.5, PVAIC1.0, PVAIC1.5, PVAIC2.5, and PVAIC5.0, respectively. Then, the solutions were stirred continuously for 20 min to obtain homogeneous solutions with uniform distribution. The homogeneous solutions were then sonicated in an 80 ◦C ultrasonic bath to remove air bubbles. Then, the viscous solutions were poured into 90 mm Petri dishes and covered with aluminum foil. The drug-loaded PVA hydrogels were physically crosslinked by repeated freeze–thaw cycles, with freezing at −20 ◦C for 20 h then thawing at room temperature for 4 h [48]. This freeze–thaw process was repeated for 4 cycles to obtain quercetin/HP-β-CD inclusion complex-loaded hydrogels. The Petri dishes containing prepared hydrogels were then sealed with parafilm and kept in the refrigerator.

## *4.6. Gelation of PVA Hydrogels Loaded with Quercetin/HP-β-CD Inclusion Complex*

To investigate the gel fractions of the hydrogels used in the study, it was first necessary to ensure that the samples had achieved a constant weight. The prepared hydrogels were cut into 0.5 cm radius round and then dried in an oven at 50 ◦C for 48 h to obtain the dry weight (Wdry). After that, the dried hydrogels were submerged in phosphate-buffered saline (PBS, pH = 7.4) at 37 ◦C for 24 h with agitation (100 rpm) and then were dried again at 50 ◦C for 48 h to obtain the hydrogel weight after extraction (Wafter extraction):

$$\text{Golation} \left( \% \right) = \frac{\text{W}\_{\text{after extraction}}}{\text{W}\_{\text{dry}}} \times 100 \tag{3}$$

### *4.7. Swelling Ratio of PVA Hydrogels Loaded with Quercetin/HP-β-CD Inclusion Complex*

The swelling ratio was measured by taking the dried hydrogel (mdry) and the wet mass (mwet) of the hydrogel after immersion in a solution for a specified time [49]. First, each hydrogel was cut into circles of 0.5 cm radius that were then immersed in 5 mL of phosphate-buffered saline (PBS, pH = 7.4) at 37 ◦C with agitation (100 rpm) for 10, 30, 60, 180, and 360 min. Finally, the swelling ratio of the hydrogels was calculated using the following equation:

$$\text{Swelling ratio} \left( \% \right) = \frac{\mathbf{m}\_{\text{wet}} - \mathbf{m}\_{\text{dry}}}{\mathbf{m}\_{\text{dry}}} \times 100 \tag{4}$$
