| Zinc Oxide nanoparticles (ZnO NPs) is a new type of inorganic functionalmaterials. Zinc Oxide has a unique optical, electrical and thermal properties, widelyused in the field of sunscreen cosmetics, paint materials, catalysis and food packaingmaterials. The chemical and physical properties of nanoparticles have a stronginfluence on the way they interact with biological components or the environment.Industrial food processing is intended to modify flavor, texture, and storage behaviorby mixing with zinc oxide nanoparticles. Due to the excellent performance andapplicant of ZnO NPs, it is the potential toxic factor for people through inhalation,ingestion, and direct skin contacting with these new products. Thus the study causepeople’s attention.Firstly, the evaluation of nanomaterials was based on their size, shape, anddistribution. Size distribution was assessed using a Malvern instrument. The figuresshowed representative transmission electron microscopy images of ZnO NPs. Theresults showed the average particle diameter of ZnO NPs:26.21±11.14nm,62.42±9.18nm and90.81±8.89nm.Secondly, to assess the cell activity, the intracellular dose of formazan wasquantified. The MTT results demonstrated that higher concentrations and longerincubation times generated more serious cytotoxicity. The24h value was chosen toconfirm the viability and accessibility of the cells and taken as the appropriate timefor the following test system. The relevant IC50values on Caco-2cells were15.55±1.19μg/ml,22.84±1.36μg/ml and18.57±1.27μg/ml.Thirdly, the results showed an enhanced trend in ROS generation due toexposure to increased concentration of Caco-2cells. At low concentrations (around6.25μg/ml ZnO NPs), the cells exposed to nano-ZnO resulted in a slight increase inintracellular ROS. Intracellular ROS induced by26nm ZnO NPs at100μg/ml for24h reached4.5fold compared to the relative control cells. ZnO NPs significantlydecreased the GSH level in Caco-2cells compared with control values. IntracellularGSH was greatly reduced (117μmol/g prot) with12.5μg/ml of26nm ZnO NPs onCaco-2cells, indicating functional damage from ROS;26nm and62nm ZnO NPs significantly decreased (106.1and119.7) intracellular GSH at25μg/ml, whereas at100μg/ml, a significant decrease occurred at both types tested. LDH result showedthat ZnO induced a significant LDH release and thus loss of membrane integrity atboth treatment concentrations. After a24h incubation,25μg/ml ZnO significantlyincreased LDH release in comparison to the controls. With90nm ZnO NPs, LDHrelease could be largely measured at50μg/ml. At less than12.5μg/ml, the90nmZnO NPs did not show any membrane damaging effects.Fourthly, the acridine orange (AO)/ethidium bromide (EB) double stainingprinciple combines the differential uptake of fluorescent DNA binding dyes acridineorange and ethidium bromide, and the morphological aspect of chromatincondensation in the stained nucleus. Cells exposed to a concentration of50μg/mlshowed that late apoptotic cells and necrotic cells became the increasinglypredominant cell type. In PI flow result, no abnormal DNA content was observed inthe control group. The diploid was94%in the G0/G1phase,3%in the S phase, and2.93%in the G2/M phase. With an increase in the concentration, the percentage ofcells during the G1phase decreased significantly, the percentage of cells in the Sphase was increasing, and the cells exposed to50μg/ml ZnO NPs during the G2phase increased significantly. The same results happened with the cells exposed to62nm and90nm ZnO NPs. Our results clearly demonstrated that cells treated with ZnONPs suffer the transition from G1to S phase and from S to G2phase. Once reachingthe G2phase, DNA damage is insufficient. There could be a replication of DNA onthe damaged template to offset the toxic effect. |
PDF Full Text Request