## 3 Results and Discussion
### 3D Braided Structures Based on PCL/CNC Wet-Spun Filaments

Table 3: Average diameter values and the respective standard deviation of the different structures. The FESEM analysis revealed notable differences between the two structures. S(a), which was fabricated without a core, exhibited a more uniform arrangement of filaments and a tighter, more cohesive braiding pattern. This uniformity is likely due to the more controlled tension during the braiding process, which was easier to achieve without the use of a core. In contrast, S(d), produced with a 6 mm core, showed a less organized arrangement of filaments with a looser braiding pattern. The larger core size contributed to a less compact overall structure as the filaments were more spread out and less tightly interwoven. The differences in organization and braiding pattern were expected due to the dimensional differences between the two structures. Cross-sectional analysis, shown in Figure 7, provided further insights into the internal structure of the braided constructs. Both structures displayed compact interior regions, indicating that the braiding process did not compromise the internal morphology of the filaments. The uniform structure observed in both cross-sections suggests that the process of twisting and braiding, even with variations in core size, did not significantly alter the core integrity of the individual filaments. Overall, the FESEM analysis demonstrated that S(a) achieved a more cohesive and uniform arrangement, making it potentially more suitable for applications where structural integrity and uniformity are critical. A structure such as S(d), while less compact, could be advantageous in scenarios where a larger diameter is necessary, though further optimization in production methods would be needed to improve its uniformity. Figure 6: FESEM images of the structure S(a) at: (**a**) 200\(\times\) magnification; (**b**) 500\(\times\) magnification and structure S(d) at (**c**) 80\(\times\) magnification; and (**d**) 200\(\times\) magnification. To evaluate the ability of PCL/CNC scaffolds to support cell adhesion and proliferation, BJ-5 ta foreskin fibroblasts were seeded onto the scaffolds and cultured for 1 and 3 days. Cell proliferation was assessed using the resazurin-based Xpert Blue Cell Viability Assay (GRISP, Portugal), which measures metabolic activity as an indicator of cell proliferation. Scaffolds S(a) and S(b) were evaluated. Table 4 summarizes the proliferation results of BJ-5 ta fibroblasts on the PCL/CNC scaffolds after 1 and 3 days. The results showed that both scaffold types supported significant fibroblast growth. After 72 h, the S(a) scaffold exhibited a proliferation rate of 81.62 \(\pm\) 29.06%, while the S(b) scaffold (2 mm) demonstrated a comparable rate of 81.50 \(\pm\) 12.89% despite differences in initial seeding densities. These findings confirm that the PCL/CNC scaffolds provide a favorable environment for fibroblast proliferation, consistent with previous studies emphasizing the biocompatibility of PCL-based materials and the reinforcing effects of CNC [53; 54; 55]. Despite structural variations, there were no significant differences in cell numbers between the two scaffold types. Nonetheless, all scaffolds supported cell culture at both time points. The consistent proliferation rates across scaffold types showcase the versatility of PCL/CNC scaffolds for cell growth. Moreover, these results confirm the findings reported in the literature, indicating that CNC incorporation can enhance the surface properties of PCL, promoting cell adhesion and growth [54].