Partial biochemical risk assessment of carbon nanotubes and carbon nanotubes/titanium dioxide nanoparticles on Glyphodes pyloalis (Lepidoptera: Pyralidae)

Cellular energy allocation (CEA) test was performed in order to investigate the effects and costs of bare carbon nanotubes (CNTs) and CNTs in combination with titanium dioxide nanoparticles (CNTs/TiO2-NPs) on Glyphodes pyloalis Walker after 24, 48 and 72 hours of exposure to 100, 200, 300, 400 and 500 ppm of the treatments. Results showed the negative correlation between total lipid amounts and concentrations of treatments (i.e. CNTs and CNTs/TiO2-NPs) as well as exposure time. Contrary to CNTs treatments, carbohydrate contents were affected by both of CNTs/TiO2-NPs concentration and time of exposure. Results showed that the effect of bare CNTs in the enhancement of glycogen content appeared significantly faster than that of CNTs/TiO2-NPs. Increasing time of exposure to all concentrations of CNTs, except for 100 ppm, prevented enhancement of protein content. The effect of bare CNTs on the reduction of protein contents was faster and greater than that of CNTs/TiO2-NPs. The results indicated that G. pyloalis cannot regulate internal CNTs and CNTs/TiO2-NPs concentrations efficiently without considerable impact on the energy reserves (Ea). The comparison of energy consumed (Ec) in treated larvae showed that CNTs/TiO2-NPs reflected the higher energy demand of the stress response than CNTs. Generally, CEA was significantly decreased as the concentration of CNTs treatments increased. More reduction in CEA amount of all treatments by CNTs/TiO2-NPs than that of the control is also probably considered as a cost to deal with detoxification when the concentration increased and at all the tested time points. Therefore, CEA test might be considered as an early biochemical biomarker for assessing immediate response of organisms after acute exposure to stressors and thus could be applied to risk assessment of nanomaterials.