## 3 Results
### Cytotoxicity Analysis  
The level of cytotoxicity and adequate cellular response are essential to define an implant material's success rate. Here, the developed porous Mg-based composite samples interacted with osteoblast-like cells (MG63 cells) to assess the viability of the cells and their apoptotic reactions. The cell viability of the samples was evaluated using an MTT assay to explore the potential of any cytotoxicity of the composites. In addition, the live/dead cell ratio was discovered using the confocal microscopy technique, which provided a clear insight into the composite's reaction with the cells. According to Figure 9, the samples consisting of aloe vera loading inside the porous substrate showed impressive cell viability of 98.64% followed by the composite coated with PLA with 84.18% cell viability. However, the sample without aloe vera inclusion and PLA coating showed a higher amount of cytotoxicity, with a cell viability of 48.37%. The corresponding confocal images highlight a similar trend of the live/dead cell ratio after reacting with the developed composite samples.  
Another study was performed to examine cell necrosis and apoptosis due to interactions with the composite samples. The MG63 cells were incubated with the porous Mg-HA composite (Sample P), aloe vera loaded composite (Sample Q), and PLA coated composite (Sample R), along with a standard control (doxorubicin added to MG63 cells) and untreated MG63 cells for 48 h. The apoptosis was quantified by flow cytometry using cells cultured with the different samples and was stained with FITC Annexin V and PI.  
Figure 10 shows a representative experiment conducted, which depicts the fluorescence intensity in MG63 cells treated with different samples. The percentage of apoptosis of cells for different samples is highlighted in Figure 10a, and it can be observed that sample Q, which consists of loaded aloe vera solution, showed only 2.11% of cells that were apoptotic, whereas, when the coating was applied (sample R), this percentage increased to 49.2%. Nonetheless, this rate was quite lower than that of the pure composite with aloe vera and coating, having a % apoptosis of 59.5% compared to the standard control and untreated MG63 cells. Moreover, Figure 10b depicts the data regarding the percentage of dead cells, live cells, early apoptosis, and late apoptosis of MG63 cells against different samples. It was observed that the aloe vera loaded sample (sample Q) had a maximum percentage of live cells, i.e., 98.29%, with an approx. negligible percentage of late apoptosis and dead cells, and only 1.71% of early apoptosis was shown by sample Q. In addition, adding a PLA layer over the substrate reduced the percentage of live cells to 51%, but it was comparatively higher than the pure porous substrate with only 39.9% live cells. Table 2 shows the data regarding the percentage of live/dead and early/late apoptosis of the cells.  
Figure 9: Cell viability analysis of the developed Mg–HA composite against the MG63 osteoblast cell line through MTT assays. (**a**) Graphical representation of %age cell viability. (**b–f**) Confocal microscopy images of the live/dead cells. (**g–k**) Optical microscopy images of the cells under the given experimental conditions.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Sample** & **\% Dead Cells** & \
\begin{tabular}{c} **\% Late** \\ **Apoptotic Cells** \\ \end{tabular} & **\% Live Cells** &
\begin{tabular}{c} **\% Early** \\ **Apoptotic Cells** \\ \end{tabular} \\ \hline Untreated & 0 & 0.18 & 99.74 & 0.08 \\ \hline Std. Control & 7.22 & 51.71 & 31.07 & 10 \\ \hline P2 & 5.35 & 25.2 & 40.29 & 29.16 \\ \hline Q2 & 0 & 0 & 98.29 & 1.71 \\ \hline R2 & 8.07 & 28.73 & 52.31 & 10.89 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Data showing MG63 Apoptosis study against different samples.