## 3 Results  
### Structure Characterization of the 3D Porous Scaffolds  
The designed and produced SF scaffolds were assessed integrating quantitative and qualitative analyses. SSF and SSFtime were analyzed by subjecting them to a microstructural and morphometric analysis by micro-CT and ultrastructural observations by FE-SEM. Table 1 reports the morphometric parameters acquired in reference to the selected ROI and, in particular, considering as the object the SF biomaterial, they represent the fraction of object volume/ material volume (Obj.V/TV) in %; the specific surface examined, object surface/volume ratio (Obj.S/Obj.V) in mm\({}^{-1}\); the object surface density (Obj.S/TV) in mm\({}^{-1}\); the mean structure thickness (St.Th) with standard deviation in mm; the mean structure separation (St.Sp) with standard deviation in mm. Table 2 reports the connectivity density (Conn. D) expressed as the number of connected structures in a mm\({}^{-3}\) and the porosity parameters: i.e., the percentage of empty spaces with respect to the total volume-porosity in %, the volume of closed pores (Po.V(cl)) in mm\({}^{3}\), and the closed porosity (Po(cl)) in %. The designed scaffold SSF has an initial Obj.V/TV of about 14.1% that is maintained over time. The parameters Obj.S/Obj.V and Obj.S/TV indicate for the SSF reasonable values that are attenuated for the SSFtime with decreases of about 15% and 14%, respectively. The maximum value of structure thickness, St.Th, was detected for the SSFtime, with an increase of about 29.3% with respect to the SSF. On the contrary, the mean value of structure separation, St.Sp, shows a decrement of about 15.2% for the SSFtime with respect to the SSF. The connectivity density, Conn.D, was higher for the SSF showing a decrement of about 16.9% for the SSFtime. Regarding the presence of pores, the maximum value of porosity is similar in the SSF and SSFtime (85.9% and 85.8%), and most of the pores are open, as evident from the Po.V and Po values. Finally, for the sample in contact with cells, SSFc, it presents an amount of Obj.V/TV about 19%, a bit higher than the SSF as well as for the parameters Obj.S/Obj.V and Obj.S/TV with increment of 14.7% and 54.4%, respectively. The values of St.Th remained consistent (\(-\)13.7%), St.Sp decreased by 30.7% with respect to the SSF, according to the presence of the cells in the volume, and considerable values were recorded for the Conn.D. The percentage of porosity is above 80% as in the other samples. The volume rendering of the acquired objects was defined by applying displayed colors relative to the same transfer function to all the samples, as shown in Figure 1. 3D models were defined from the volume reconstruction of the acquired 2D set of images. An example of 3D reconstruction is illustrated in Figure 2 for the selected ROI and a set of \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Label** & **Description** & **Obj.V/TV** & **(Obj.S/Obj.V)** & **(Obj.S/TV)** & **St.Th \(\pm\) SD** & **St.Sp \(\pm\) SD** \\  & **(\%)** & **(mm\({}^{-1}\))** & **(mm\({}^{-1}\))** & **(mm)** & **(mm)** \\ \hline SSF & SF scaffold; no cells & 14.062 & 88.012 & 12.377 & 0.043 \(\pm\) 0.015 & 0.166 \(\pm\) 0.063 \\ SSFtime & SF scaffold-24 months; no cells & 14.200 & 74.873 & 10.632 & 0.056 \(\pm\) 0.020 & 0.141 \(\pm\) 0.047 \\ SSFc & SF scaffold; with cells & 18.925 & 100.991 & 19.113 & 0.037 \(\pm\) 0.015 & 0.115 \(\pm\) 0.051 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: 3D Micro-CT analysis, for the selected volume ROI: morphological parameters. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Label** & **Description** & **Conn.D** & **Porosity** & **Po.V(cl)** & **Po(cl)** \\  & **(mm\({}^{-3}\))** & **(\%)** & **(mm\({}^{3}\))** & **(\%)** \\ \hline SSF & SF scaffold; no cells & 838.9 & 85.9 & 0.0000 & 0.0004 \\ SSFtime & SF scaffold-24 months; no cells & 717.2 & 85.8 & 0.0000 & 0.0043 \\ SSFc & SF scaffold; with cells & 2497.2 & 81.1 & 0.0001 & 0.0224 \\ \hline \hline \end{tabular}
\end{table}