## 3 Results
### Cell Compatibility Study of the NPs  
Prior to the cytotoxicity study of the NPs, the surfactants used during the process of their fabrication were tested for biocompatibility (Figure 9). The three surfactants--Tween 20, Kolliphor P188, and Brij 010--that gave the best results in terms of the NPs size were selected for this study; the fourth--poly(vinyl alcohol) (Mowiol 4-88)--Which has shown less satisfactory results in terms of the NPs' size, was used as a reference compound since it is known for its low toxicity [(44; 45)]. The experiments were performed using four established cell lines--HeLa, A549, Hepa 1-6, and RAW264.7. Based on the results of the cell compatibility study (Figure 9), and taking into account the effectiveness when fabricating the NPs, Tween 20 has been recognized as one of the most promising surfactants for making biocompatible NPs on the basis of the AABB polymers--**1F6**, **1L6**, **4F4**, and **8L6**. The NPs made from DMSO solution of these polymers in the presence of Tween 20 were subjected to a subsequent cytotoxicity study. The results are given in Figure 10.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{3}{*}{**Time**} & \multicolumn{5}{c}{**Surfactant**} \\ \cline{2-7}  & **Tween 20** & **Tween 80** & **Brij 010** & **Tween 20** & **Tween 80** & **Brij 010** \\ \cline{2-7}  & \multicolumn{5}{c}{**MPD (nm) \(\pm\) SD**} \\ \cline{2-7}  & \multicolumn{5}{c}{**At r.t. (23–25 °C)**} \\ \hline \multirow{3}{*}{Freshly prepared} & **159 \(\pm\) 3** & **162 \(\pm\) 15** & **166 \(\pm\) 5** & **159 \(\pm\) 3** & **162 \(\pm\) 15** & **166 \(\pm\) 5** \\  & [0.131 \(\pm\) 0.003] & [0.088 \(\pm\) 0.001] & [0.131 \(\pm\) 0.003] & [107 \(\pm\) 0.012] & [0.088 \(\pm\) 0.001] \\ \hline \multirow{3}{*}{A week later} & **179 \(\pm\) 2** & **169 \(\pm\) 10** & **186 \(\pm\) 5** & **183 \(\pm\) 8** & **167 \(\pm\) 8** & **187 \(\pm\) 5** \\  & [0.123 \(\pm\) 0.007] & [0.114 \(\pm\) 0.005] & [0.102 \(\pm\) 0.011] & [0.135 \(\pm\) 0.005] & [0.112 \(\pm\) 0.015] & [0.095 \(\pm\) 0.004] \\ \hline \multirow{3}{*}{A month later} & **186 \(\pm\) 7** & **165 \(\pm\) 11** & **180 \(\pm\) 3** & **189 \(\pm\) 2** & **188 \(\pm\) 6** & **184 \(\pm\) 9** \\  & [0.129 \(\pm\) 0.012] & [0.103 \(\pm\) 0.009] & [0.094 \(\pm\) 0.013] & [0.149 \(\pm\) 0.008] & [0.121 \(\pm\) 0.005] & [0.109 \(\pm\) 0.011] \\ \hline \multirow{3}{*}{3 months later} & **195 \(\pm\) 10** & **200 \(\pm\) 15** & **181 \(\pm\) 3** & **200 \(\pm\) 8** & **200 \(\pm\) 8** & **189 \(\pm\) 2** \\  & [0.145 \(\pm\) 0.015] & [0.121 \(\pm\) 0.004] & [0.113 \(\pm\) 0.009] & [0.138 \(\pm\) 0.005] & [0.115 \(\pm\) 0.010] & [0.118 \(\pm\) 0.015] \\ \hline \end{tabular}
\end{table}
Table 19: The stability of the 8L6 NPs upon storage.  
Figure 8: TEM images of **8L6** (**A**) and **1L6** (**B**) NPs.  
Figure 10: Percentage of viable cells after the 24 h incubation of four different types of NPs (5.0 \(\mathrm{\SIUnitSymbolMicro\SIUnitSymbolMicro m}\)L) with: (**A**) HeLa cell line; (**B**) Hepa 1-6 cell line; (**C**) A549 cell line; (**D**) RAW264.7 cell line. The NPs were fabricated from DMSO solution in the presence of Tween 20.  
Figure 9: Percentage of viable cells after the 24 h incubation of four different types of surfactants (25 \(\mathrm{\SIUnitSymbolMicro\SIUnitSymbolMicro g}\)/mL) with: (**A**) HeLa cell line; (**B**) Hepa 1-6 cell line; (**C**) A549 cell line; (**D**) RAW264.7 cell line.