The development of nanotechnology has led to the increased production of zinc oxide nanoparticles (ZnO‐NPs) and their application in a wide variety of everyday products. It creates the need for a full assessment of their safety for humans. The aim of the study was to assess the toxic effects of ZnO‐NPs on model human cells of the immune system: U‐937, HL‐60, HUT‐78, and COLO‐720L. Particular attention was paid to the direct interaction of the nanoparticles with membrane lipids and the role of zinc ions in the mechanism of their toxicity. Cell viability, lipid peroxidation, cell membrane integrity, and the amount of zinc ions released from nanoparticles were tested. Disruption in cell metabolism was noted for ZnO‐NPs concentrations from 6.25 mg/L. Contact with ZnO‐NPs caused lipid peroxidation of all cells and correlated with membrane disruption of HL‐60, HUT‐78, and COLO‐720L cells. Model monolayers (Langmuir technique) were used to assess the interaction of the nanoparticles with the studied lipids. Physicochemical parameters, such as the area per molecule at maximal layer compression, the pressure at which the monolayer collapses, and the static compression modulus, were calculated. The models of the HL‐60 and U‐937 cell membranes under ZnO‐NPs treatment reacted in a different way. It has also been shown that Zn2+ are not the main causative factor of ZnO‐NPs toxicity. Investigating the early stages of mechanism of nanoparticles toxicity will allow for a more complete risk assessment and development of methods for a safer synthesis of engineering nanomaterials.
The aim of the study was to investigate the effect of application of exogenous hyaluronic acid (HA) of various molecular weights on the cells of human immune system. Two cell lines HL-60 and U-937 with various ability to differentiation were chosen. HL-60 cells were differentiated to macrophages and granulocytes, whereas U-937 only to macrophages. For all investigated cell systems the most cytotoxic effect, indicated as a decrease of cell viability, was found at HA dose equal to 200 mg/L. However, greater effect was observed for differentiated cells and at longer exposure to HA. The possibility of HA interaction with both specific receptors and membrane lipids was tested by determination of biotin-labelled HA binding to cell surface and analysis of physicochemical parameters of model membranes.
In the present work, Langmuir monolayers were used to study the interaction of putrescine (a cationic antioxidant) with anionic charged membranes (1,2-dioleoyl-sn-glycerol-3-phosphate) under oxidative stress caused by the presence of ozone in the water phase. Calcium ions and acidic environment were used to compare the electrostatic and antioxidant effects of putrescine with those of an inorganic cation. It has been shown that the main role of putrescine in protecting systems against oxidation is its rapid reaction with ROS. The initial rate of ROS neutralization rose as the concentration of putrescine increased. No such reaction was observed for calcium ions. The consequence of putrescine’s ozone removal was lesser lipid destruction that depended on the pH conditions.
Effectiveness of green tea (compared to two single polyphenols) in removing ozone derived reactive oxygen species acting on dioleoylphosphatidylcholine monolayers was determined. Lipid oxidation was followed by changes in mechanical properties of the layer spread on the aqueous subphase containing various amounts of ozone in the presence and absence of polyphenolics. It was shown that the tea extract (containing 8.5 x 10 mg/cm polyphenols) is capable of inactivating 0.4 ppm ozone. The DPPH radical scavenging test set polyphenols in the order of increasing activity, consistent with their protective effect in relation to lipid oxidation, showing the highest efficacy of EGCG.
Three-finger toxins are naturally occurring proteins in Elapidae snake venoms. Nowadays, they are gaining popularity because of their therapeutic potential. On the other hand, these proteins may cause undesirable reactions inside the body′s cells. A full assessment of the safety of Naja ashei venom components for human cell application is still unknown. The aim of the study was to determine the effect of the exogenous application of three-finger toxins on the cells of monocytes (U-937) and promyelocytes (HL-60), with particular emphasis on the modification of their membranes under the influence of various doses of 3FTx protein fraction (0–120 ng/mL). The fraction exhibiting the highest proportion of 3FTx proteins after size exclusion chromatography (SEC) separation was used in the experiments. The structural response of cell membranes was described on the basis of single-component and multi-component Langmuir monolayers that mimicked the native membranes. The results show that the mechanism of protein–lipid interactions depends on both the presence of lipid polar parts (especially zwitterionic type of lipids) and the degree of membrane saturation (the greatest-for unsaturated lipids). The biochemical indicators reflecting the tested cells (MDA, LDH, cell survival, induction of inflammation, LD50) proved the results that were obtained for the model.
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