## 3 Results and Discussion
\begin{table}
\begin{tabular}{c c c} \hline
**Wavenumber (cm\({}^{-1}\))** & **Description of the Vibrational Band** & **Ref.** \\ \hline
3545 & Asymmetric stretching of the O-H bond & [37; 39] \\ \hline
3477 & Symmetric stretching of the O-H bond & [37; 40] \\ \hline
2980 & Asymmetric stretching of aliphatic C-H bond with C (bonded to aromatic chain) & [37; 40] \\ \hline
2918 & Symmetric stretching of aliphatic C-H bond with C (bonded to aromatic chain) & [37; 40] \\ \hline
1647 & Symmetric stretching of the aromatic C=O bond & [37; 39; 41] \\ \hline
1519 & Asymmetric stretching of the C=C bond & [37; 40; 41] \\ \hline
1444 & Symmetric stretching of the C=C bond & [37; 40] \\ \hline
1300 & Asymmetric stretching of the C-O bond (attached to aromatic chain) & [37; 41] \\ \hline
1276 & Symmetric link stretching C-O (linked to aromatic chain) & [37; 41] \\ \hline \end{tabular}
\end{table} 
Table 2: Characteristic vibrational bands of the Hsp drug detected in the FTIR spectrum. These lower intensity peaks suggest that the Hsp available in the filaments is dispersed in the amorphous matrix of the polymer, with an increase in the drug contact surface area. This dispersion is an important result for the application of the filaments containing Hesperidin, considering that the crystalline phase of the drug is poorly soluble in water and has a low dissolution rate when administered in the form of oral solid solutions (a limiting factor for its bioavailability). Thus, as the filaments were extruded at 130 \({}^{\circ}\)C (a temperature much lower than the Hsp melting temperature), part of the Hesperidin micrometric particle agglomerates (as observed in the SEM results) tends to dissolve and/or to decrease in size in the polymer bulk during extrusion. This behavior, already mentioned for other Hesperidin solid dispersions using poly(ethylene glycol) and poly(vinyl pyrrolidone) as the polymer matrix, facilitates the drug dissolution and absorption in the action medium [45; 47]. Figure 10 shows the DSC curves of the E100, E100/Hsp(\(-\)), and E100/Hsp(\(+\)) filaments and of E100 granules (as provided by the manufacturer), in the range 30 to 135 \({}^{\circ}\)C, for two complete heating and cooling cycles. It is possible to observe that all filament samples (materials that have previously been heated to 130 \({}^{\circ}\)C) present thermal characteristics similar to those of the E100 polymer in its original form, during the two test cycles, during which no degradation of the materials is detected. In fact, it is known from the literature that the degradation of the E100 polymer begins above 200 \({}^{\circ}\)C, and that complete degradation occurs above 300 \({}^{\circ}\)C [24; 25; 26] (not only is the thermal stability of the polymer at this extrusion temperature shown, but also that there is no loss of material mass up to around 200 \({}^{\circ}\)C). Figure 9: DSC curves of the pristine Hsp, and E100, E100/Hsp(\(-\)), and E100/Hsp(\(+\)) filaments. Thus, it is possible to infer from the combined analysis of the DSC, XRD, FTIR, and ATR spectra that the hot-melt extrusion (HME) process at 130 \({}^{\circ}\)C is suitable for the production of E100/Hsp hybrid filaments for biomedical use, since the process does not cause changes in the chemical composition and/or the degradation of the polymer or the drug [24; 26; 42]. The results of the drug dissolution tests in simulated gastric and intestinal fluids (pH = 1.2 and pH = 7.2, respectively) are shown in Figure 11. In each solution, the drug release profiles were verified from E100/Hseperidin filament samples at low (E100-Hsp(\(-\))) and high (E100-Hsp(+)) concentration levels. Figure 11: Drug release profiles in simulated gastric and intestinal media from the filament-type polymeric matrix. Tests were performed for samples with low (E100/Hsp(\(-\))) and high (E100-Hsp(+)) drug concentration in E100 matrix bulk. Figure 10: Cyclic DSC heating and cooling curves for the E100 granules, and E100, E100/Hsp(\(-\)), and E100/Hsp(\(+\)) filaments.