## 3 Results
### Toxicological Assay  
To assess the chronic oral toxicity of mesoporous carbon nanoparticles synthesized from waste onion peel, a survival assay was performed with newly hatched male (Figure 4) and female (Figure 5) flies. The flies were fed with different doses (10, 100, and 1000 \(\upmu\)g/mL) of CNS500 (Figures 4A and 5A), CNS600 (Figures 4B and 5B), CNS700 (Figures 4C and 5C), CNS800 (Figures 4D and 5D), CNS900 (Figures 4E and 5E), and CNS1000 (Figures 4F and 5F) CNSs and observed for a period of 25 days. The male flies treated with CNS500, CNS600, CNS700, CNS800, CNS900, and CNS1000 nanoparticles at the 10 \(\upmu\)g/mL dose did not show a significant difference in survival compared to control flies. However, male flies treated with 100 \(\upmu\)g/mL of nanoparticles showed a difference in the survival curve for CNS500 (Figure 4A) and CNS600 (Figure 4B) CNSs, respectively. Similarly, male flies treated with 1000 \(\upmu\)g/mL of nanoparticles showed a significant difference in survival rate for CNS500 (Figure 4A), CNS600 (Figure 4B), CNS800 (Figure 4D), and CNS900 (Figure 4E) CNSs, respectively. In female flies, only CNS500-treated flies showed a significant difference in survival rate for 100 and 1000 \(\upmu\)g/mL (Figure 5B) concentrations. However, at the 10 \(\upmu\)g/mL dose, they survived as compared to the control flies. Other nanoparticles, i.e., CNS600 (Figure 5b), CNS700 (Figure 5C), CNS800 (Figure 5D), CNS900 (Figure 5E), and CNS1000 (Figure 5F), showed no significant difference in survival rate at 10, 100, and 1000 \(\upmu\)g/mL concentrations, respectively. In summary, the survival curves for the control and CNS-treated groups did not exhibit any major difference among male and female flies (Figures 4 and 5). Based on these findings regarding the survival rate, all other biochemical and behavioral assays in adult males and females were performed after 25 days of exposure to the respective nanoparticles. Figure 3: BET specific surface area and pore volume (**A**), pore width and \(\rm I_{D}/I_{G}\) (**B**), and particle sizes of different carbon materials (**C**). The negative geotaxis or climbing assay was performed independently for males and females. In all CNS-treated groups (CNS500, CNS600, CNS700, CNS800, CNS9900, and CNS1000), since there was no significant difference in the survival of both male and female flies for most of the nanoparticle concentrations tested, only the flies treated with the highest concentration of CNS were considered for the negative geotaxis or climbing assay. The percentages of male flies that were able to cross the 20 cm mark in one minute (three times/vial and three food vials per dose) in control and CNS-treated (CNS500, CNS600, CNS700, CNS800, CNS900, and CNS1000) groups were 95, 77.8, 78.8, 77.8, 78.8, 87, and 80.6, respectively (Figure 6A). Similarly, the percentages of female flies that were able to cross the expected mark in one minute in the control and CNS-treated (CNS500, CNS600, CNS700, CNS800, CNS900, and CNS1000) groups were 91.7, 81, 84.6, 63, 83, 94.9, and 82, respectively (Figure 6B). Only female flies in the CNS700-treated group showed slight difficulty in climbing. However, in all other treated groups, both male and female flies showed no statistically significant difference compared to the control group. The acetylcholinesteraseinesterase (AChE) activity was estimated in male and female flies in response to dietary exposure of CNS500, CNS600, CNS700, CNS800, CNS900, and CNS1000 CNSs at a 1000 \(\upmu\)g/mL dose. The analysis revealed no significant difference between control and treatment groups, suggesting that 25 days of dietary exposure to mesoporous carbon nanoparticles did not elicit major neurotoxicity (Figure 7). Figure 4: Survival assay curve of male flies treated with mesoporous carbon nanoparticles (**A**) CNS500, (**B**) CNS600, (**C**) CNS700, (**D**) CNS800, (**E**) CNS900, and (**F**) CNS1000 at 10, 100, and 1000 \(\upmu\)g/mL doses, respectively. Here, the black curve represents the survival rate of control flies.