# Engineering Biomimetic Gelatin Based Nanostructures as Synthetic Substrates for Cell Culture
## 3 Results  
Morphology of PCL/Gelatin/Poxamer 188 (P188) Scaffolds in Comparison with PCL/Gelatin and PCL Nanofibers  
SEM images and diameter distribution of PCL and PCL/gelatin (90:10) composites are shown in Figure 1, Figure 2 and Table 2, respectively. Figures 3-5, on the other hand, represents SEM images and diameter distribution of three different samples of PCL/gelatin/P188 with a concentration ratio of 85:10:5, 80:10:10, and 70:10:20 respectively. Table 2 shows the average diameter along with the standard deviation of all the five samples electrospun at four different voltages (18 kV, 20 kV, 22 kV, and 24 kV) obtained using ImageJ analysis of \(\times\)10,000 magnified samples. It can be seen that the average diameter of all the fibrous samples is in the nanometer range. Moreover, it was observed that the scaffolds not only had fibers of varying diameter, but the diameter of the individual fibers vary along its length. Beads were also observed in all composite nanofibrous scaffolds. To determine the nanotopography of the scaffold, the nanofibers were further characterized using AFM. The topographic variation with the change in the composition of the fibers can be clearly observed in the AFM images (Figure 6). The mean roughness value (Ra) of scaffolds was also obtained from the AFM images. The roughness average (Ra) is an arithmetic mean value of individual height measurements obtained using AFM of peaks and valleys on the surface of the scaffold [43]. Ra value is directly proportional to roughness [43]. Figure 1: SEM images of the polycaprolactone (PCL) nanofibers electrospun at **(A)** 18 kV, **(B)** 20 kV, **(C)** 22 kV, and **(D)** 24 kV voltages. The images were measured at a magnification of \(\times\)8000 to \(\times\)10,000. Figure 3: SEM images of the PCL/gelatin/P188 (85:10:5 %w/v) composite nanofibers electrospun at (**A**) 18 kV, (**B**) 20 kV, (**C**) 22 kV, and (**D**) 24 kV voltages. The images were measured at a magnification of \(\times\)9000 to \(\times\)10,000. Figure 2: SEM images of the PCL/gelatin (90:10 %w/v) composite nanofibers electrospun at (**A**) 18 kV, (**B**) 20 kV, (**C**) 22 kV, and (**D**) 24 kV voltages. The images were measured at a magnification of \(\times\)8000 to \(\times\)10,000. Figure 4: SEM images of the PCL/gelatin/188 (80:10:10 %w/v) composite nanofibers electrospun at (**A**) 18 kV, (**B**) 20 kV, (**C**) 22 kV, and (**D**) 24 kV voltages. The images were measured at a magnification of \(\times\)9000 to \(\times\)10,000. Figure 5: SEM images of the PCL/gelatin/P188 (70:10:20 %w/v) composite nanofibers electrospun at (**A**) 18 kV, (**B**) 20 kV, (**C**) 22 kV, and (**D**) 24 kV voltages. The images were measured at a magnification of \(\times\)8000 to \(\times\)10,000. \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & \multicolumn{4}{c}{**Average Fiber Diameter (nm) of Fibers Electrospun at**} \\ \hline
**Samples** & **18 kV** & **20 kV** & **22 kV** & **24 kV** \\ \hline PCL & 383 \(\pm\) 301 & 425 \(\pm\) 419 & 453 \(\pm\) 314 & 487 \(\pm\) 302 \\ PCL/Gelatin (90:10) & 307 \(\pm\) 109 & 595 \(\pm\) 340 & 282 \(\pm\) 190 & 384 \(\pm\) 245 \\ PCL/Gelatin/ P188 (85:10:5) & 280 \(\pm\)126 & 297 \(\pm\) 181 & 390 \(\pm\) 158 & 291 \(\pm\) 109 \\ PCL/Gelatin/ P188 (80:10:10) & 361 \(\pm\) 175 & 337 \(\pm\) 129 & 327 \(\pm\) 196 & 239 \(\pm\) 107 \\ PCL/Gelatin/ P188 (70:10:20) & 363 \(\pm\) 336 & 463 \(\pm\) 317 & 306 \(\pm\) 163 & 227 \(\pm\) 62 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: The average fiber diameter (n = 100) of the five different fibrous scaffolds along with their standard deviation. Figure 6: The height and phase AFM images of **(A)** PCL, **(B)** PCL/gelatin, **(C)** PCL/gelatin/P188 of concentration 85:10:5 %w/v, **(D)** PCL/gelatin/P188 of concentration 80:10:10 %w/v, and **(E)** PCL/gelatin/P188 of concentration 70:10:20 %w/v electrospun at 22 kV along with the (the scanning area was 6.6 \(\upmu\)m to 6.6 \(\upmu\)m).