The long-term oral exposure to titanium dioxide impaired immune functions and triggered cytotoxic and genotoxic impacts in rats

BackgroundTitanium dioxide "TiO₂, E171″ is a widely used food additive that exists in various everyday food products all over the world together with vast applications in cosmetics and industry. However, many toxicological aspects particularly following oral exposure still unclear.MethodsHence, this study was planned to examine the effect of oral exposure of male Wistar rats to two doses of TiO₂ (20 or 40 mg/kg b.wt.) through oral gavage once daily for 90 consecutive days on the blood components, immunity, cytotoxic, and genotoxic indicators.ResultsA dose-dependent leukopenia, eosinophilia, neutrophilia, and thrombocytopenia were noted. Also, the immunoglobins G (IgG) and IgM were significantly elevated in TiO₂ treated rats. The phagocytic activities, lysozyme, nitric oxide, and immunoglobulin levels were significantly depleted following TiO₂ exposure. A significantly reduced lymphocyte proliferation but elevated LDH activity was prominent in TiO₂ treated rats. Different pathological perturbations were observed in both splenic tissue and bone marrow. A marked increase in CD4⁺ and CD8⁺ immunolabeling was evident. A significant increase in the comet variables was recorded in response to the exposure of rats to the increasing level of TiO₂ at both levels.ConclusionOverall, these results indicated that TiO₂ could induce hematotoxicity, genotoxic, and immunotoxic alterations with exposure for long durations.     

The genotoxic and cytotoxic effects of ribavirin in rat bone marrow

The genotoxicity of the 2-furylethylene derivative 1-(5-bromofur-2-yl)-2-nitroethene (2-betaNF) has been evaluated in cultured human peripheral blood lymphocytes at concentrations ranging from 0.5 to 15microg/ml. The frequencies of micronuclei (MN) and sister-chromatid exchanges (SCEs) were used and scored as indicators of genetic damage. To asses the role of the metabolism mediated by the enzymes present in the S9 mix, over the possible genotoxic potential of the test agent, the cultures for MN and SCE demonstrations were treated for 3h in presence and in absence of rat liver microsomal fraction. The results indicate that, under the experimental conditions used, the test agent does not induce significant increases in the frequency of micronucleated cells, irrespective of the presence/absence of metabolic fraction. Nevertheless, a slight increase in the SCE frequency was observed in those cultures treated without the S9 mix; although this slight increase disappeared in the experiments carried out with the microsomal fraction. In addition, cytotoxic/cytostatic effects of (2-betaNF) were observed mainly in the cultures treated without the S9 fraction.     

The genotoxic and cytotoxic effects of ribavirin in rat bone marrow

The genotoxic and cytotoxic effects of the antiviral drug, ribavirin, was studied in rat bone marrow by employing the micronucleus assay. Ribavirin in doses of 10, 15, 20, 30, 50, 75, 100 and 200 mg/kg, and cyclophosphamide (CP) 40 mg/kg (only for sex-difference study) were injected intraperitoneally. Bone marrow was collected at 24 h and 48 h following the injection. To evaluate the recovery, the bone marrow was also sampled at 72 h from 20, 100 and 200 mg/kg treated rats. The micronucleus assay was conducted according to the standard procedure. Ribavirin elevated the incidence of micronuclei (except 10 mg/kg) in erythrocytes (P<0.01). The micronucleated polychromatic erythrocytes showed the initial steep increase at 15 and 20 mg/kg dose level, then with the gradual increase, possibly due to the limited metabolism and action of higher doses. The incidence of micronucleated normochromatic erythrocytes was not dose dependent. The effect was more at 48 h than 24 h due to prolonged toxicity of the drug or its metabolites, and by 72 h, recovery was observed eventhough the genotoxicity was significant. The PCE% decreased as the dose was increased up to 75 mg/kg, then without much difference between two higher doses. Only 100 mg/kg ribavirin and CP showed more toxicity on male rats. Cytotoxicity was seen due to hindered erythropoiesis or cell destruction. Our findings suggest that ribavirin is genotoxic and cytotoxic agent for rat bone marrow.     

Safrole-2',3'-oxide induces cytotoxic and genotoxic effects in HepG2 cells and in mice

Safrole-2',3'-oxide (SAFO) is a reactive electrophilic metabolite of the hepatocarcinogen safrole, the main component of sassafras oil. Safrole occurs naturally in a variety of spices and herbs, including the commonly used Chinese medicine Xi xin (Asari Radix et Rhizoma) and Dong quai (Angelica sinensis). SAFO is the most mutagenic metabolite of safrole tested in the Ames test. However, little or no data are available on the genotoxicity of SAFO in mammalian systems. In this study, we investigated the cytotoxicity and genotoxicity of SAFO in human HepG2 cells and male FVB mice. Using MTT assay, SAFO exhibited a dose- and time-dependent cytotoxic effect in HepG2 cells with TC(50) values of 361.9μM and 193.2μM after 24 and 48h exposure, respectively. In addition, treatment with SAFO at doses of 125μM and higher for 24h in HepG2 cells resulted in a 5.1-79.6-fold increase in mean Comet tail moment by the alkaline Comet assay and a 2.6-7.8-fold increase in the frequency of micronucleated binucleated cells by the cytokinesis-block micronucleus assay. Furthermore, repeated intraperitoneal administration of SAFO (15, 30, 45, and 60mg/kg) to mice every other day for a total of twelve doses caused a significant dose-dependent increase in mean Comet tail moment in peripheral blood leukocytes (13.3-43.4-fold) and in the frequency of micronucleated reticulocytes (1.5-5.8-fold). Repeated administration of SAFO (60mg/kg) to mice caused liver lesions manifested as a rim of ballooning degeneration of hepatocytes immediately surrounding the central vein. Our data clearly demonstrate that SAFO significantly induced cytotoxicity, DNA strand breaks, micronuclei formation both in human cells in vitro and in mice. More studies are needed to explore the role SAFO plays in safrole-induced genotoxicity.     

In vitro genotoxic effects of titanium dioxide nanoparticles (n‐TiO2) in human sperm cells

Titanium dioxide nanoparticles (TiO₂‐NPs) are one of the most widely engineered nanoparticles used. The study has been focused on TiO ₂‐NPs genotoxic effects on human spermatozoa in vitro. TiO ₂‐NPs are able to cross the blood–testis barrier induced inflammation, cytotoxicity, and gene expression changes that lead to impairment of the male reproductive system. This study presents new data about DNA damage in human sperms exposed in vitro to two n‐TiO ₂ concentrations (1 µg/L and 10 µg/L) for different times and the putative role of reactive oxygen species (ROS) as mediators of n‐TiO ₂ genotoxicity. Primary n‐TiO ₂ characterization was performed by transmission electron microscopy. The dispersed state of the n‐TiO ₂ in media was spectrophotometrically determined at 0, 24, 48, and 72 hr from the initial exposure. The genotoxicity has been highlighted by different experimental approaches (comet assay, terminal deoxynucleotidyl transferase dUTP nick end labeling [TUNEL] test, DCF assay, random amplification of polymorphic DNA polymerase chain reaction [RAPD‐PCR]). The comet assay showed a statistically significant loss of sperm DNA integrity after 30 min of exposure. Increased threshold of sperm DNA fragmentation was highlighted after 30 min of exposure by the TUNEL Test. Also, the RAPD‐PCR analysis showed a variation in the polymorphic profiles of the sperm DNA exposed to n‐TiO ₂. The evidence from the DCF assay showed a statistically significant increase in intracellular ROS linked to n‐TiO ₂ exposure. This research provides the evaluation of n‐TiO ₂ potential genotoxicity on human sperm that probably occurs through the production of intracellular ROS.     

Relative efficacy of short-term tests in detecting genotoxic effects of cadmium chloride in mice in vivo

The ability of intraperitoneally administered cadmium chloride (0.42-6.75 mg/kg) to induce genotoxic damage in somatic and germ cells of mice was evaluated using chromosomal aberrations, sister-chromatid exchanges (SCE), micronuclei and sperm-head abnormalities as end-points. A significant increase in the frequency of chromosomal aberrations and SCEs was observed in almost all treated series when compared to the negative control. Micronucleus formation in polychromatic erythrocytes was not affected significantly except at the highest concentration used (6.75 mg/kg). Significant differences were observed in the frequency of sperm with abnormal head morphology at all concentrations tested except the lowest one. The clastogenic effects of cadmium chloride in both somatic and germinal cells are found to depend directly on the concentrations used.     

The genotoxic and cytotoxic effects of nicotine in the mouse bone marrow

The objective of the present study was to investigate the potential of nicotine to induce micronucleated polychromatic erythrocytes (MNPCE) in bone marrow of male and female mice. Cyclophosphamide at 40mg/kg was used as positive control clastogen. Single doses of 4, 8 or 16mg/kg nicotine were given via oral intubation and bone marrow was sampled at 18, 24, 30, 36 and 48h after treatment. Cyclophosphamide yielded the expected positive results. Despite the evident signs of acute toxicity shown by the animals, mainly at the 8 and 16mg/kg doses of nicotine, and the reduction in the % PCE, the results show that the MNPCE frequency in male and female mice was not affected by treatment with any of the selected doses of nicotine, in either of the sampling times 18 or 24h. However, at 30 and 36h after treatment, the MNPCE showed significant increases in both genders after doses of 8 and 16mg/kg. A sex-dependent response was recorded, with males having more MNPCE than females after treatment with 8 or 16mg/kg nicotine and sampling at 30h. However, at 36h more MNPCE were induced in females than in males, suggesting different degrees of dose interaction in the sexes under the conditions of the assay. The response was directly correlated with bone-marrow toxicity, as greater bone-marrow suppression was noted in females than in males when 36h samples were examined. By 48h recovery was observed even though the cytotoxicity was high. These findings suggest that nicotine at high doses and after prolonged time intervals is genotoxic and cytotoxic for mouse bone marrow.     

The cytogenetic evaluation of in vivo genotoxic and cytotoxic activity using rodent somatic cells

With the growing realization that in vitro short-term tests for genotoxicity can never fully mimic in vivo conditions, the evaluation of genotoxic damage in somatic cells of rodents has played an increasingly important role in assessing the carcinogenic potential of suspect compounds. Among the various genotoxic endpoints assessed in in vivo somatic cell assays, cytogenetic endpoints (e.g., chromosomal aberrations, micronuclei, sister chromatid exchanges) continue to be used most frequently. The purpose of this paper is to demonstrate the utility of evaluating different cytogenetic endpoints in the same animal, using as examples studies to evaluate the in vivo genotoxic potential of benzene, of methylisocyanate, and of butadiene, chloroprene and isoprene.Abbreviations CA chromosomal aberrations - MI mitotic index - MIC methylisocyanate - MN-NCE micronucleated monochromatic erythrocytes - MN-PCE micronucleated polychromatic erythrocytes - SCE sister chromatid exchange     

四种苏丹红染料对小鼠体内血液的影响

目的探讨苏丹红对小白鼠血液和组织器官的影响。方法取小鼠连续12 d腹腔注射不同剂量苏丹红Ⅰ、Ⅱ、Ⅲ、Ⅳ（0、40、80、160 mg/kg）,末次给药24 h后采集血样,用血细胞分析仪检测血常规指标,毛细血管法测定凝血时间,剖腹取主要器官称重,计算脏器系数。结果苏丹红Ⅰ和Ⅱ组血液红细胞数明显减少,而苏丹红Ⅲ和Ⅳ组不明显,苏丹红不同剂量之间比较,低剂量苏丹红Ⅰ和高剂量苏丹红Ⅱ组比苏丹红Ⅲ和Ⅳ组血液红细胞数变化明显;苏丹红Ⅰ和Ⅱ组血液血红蛋白含量明显降低,而苏丹红Ⅲ和Ⅳ组血红蛋白含量变化不明显。四种不同剂量苏丹红组小鼠血液中血小板数量减少,随着剂量增加小鼠血液凝固时间延长。随着苏丹红剂量增加,苏丹红I和II组小鼠血液白细胞数比对照组明显增加,苏丹红Ⅲ和Ⅳ组白细胞数有增加趋势但差异不显著。与对照组比较,苏丹红组小鼠血液白细胞数明显增加、而淋巴细胞和单核细胞显著减少。随着苏丹红注射剂量增加,肾脏和脾脏脏器系数较对照组明显增大,肝脏脏器系数变化不明显。结论苏丹红对小鼠血液细胞、血红蛋白、血小板和凝血时间以及组织器官都有不同程度影响。     

Inflammatory and genotoxic effects of diesel particles in vitro and in vivo

Recent studies have identified an indirect genotoxicity pathway involving inflammation as one of the mechanisms underlying the carcinogenic effects of air pollution/diesel exhaust particles (DEP). We investigated the short-term effects of DEP on markers of inflammation and genotoxicity in vitro and in vivo. DEP induced an increase in the mRNA level of pro-inflammatory cytokines and a higher level of DNA strand breaks in the human lung epithelial cell line A549 in vitro. For the in vivo study, mice were exposed by inhalation to 20 or 80 mg/m3 DEP either as a single 90-min exposure or as four repeated 90-min exposures (5 or 20 mg/m3) and the effects in broncho-alveolar lavage (BAL) cells and/or lung tissue were characterized. Inhalation of DEP induced a dose-dependent inflammatory response with infiltration of macrophages and neutrophils and elevated gene expression of IL-6 in the lungs of mice. The inflammatory response was accompanied by DNA strand breaks in BAL cells and oxidative DNA damage and increased levels of bulky DNA adducts in lung tissue, the latter indicative of direct genotoxicity. The effect of a large single dose of DEP was more pronounced and sustained on IL-6 expression and oxidative DNA damage in the lung tissue than the effect of the same dose administered over four days, whereas the reverse pattern was seen in BAL cells. Our results suggest that the effects of DEP depend on the rate of delivery of the particle dose. The mutation frequency (MF), after DEP exposure, was determined using the transgenic Muta Mouse and a similar exposure regimen. No increase was observed in MF in lung tissue 28-days after exposure. In conclusion, short-term exposure to DEP resulted in DNA strand breaks in BAL cells, oxidative DNA damage and DNA adducts in lungs; and suggested that DNA damage in part is a consequence of inflammatory processes. The response was not associated with increased MF, indicating that the host defence mechanisms were sufficient to counteract the adverse effects of inflammation. Thus, there may be thresholds for the inflammation-associated genotoxic effects of DEP inhalation.     

Modulation of genotoxic and cytotoxic effects of aromatic amines in monolayers of rat hepatocytes

Cultured rat hepatocytes exposed to 2-acetylaminofl uorene (AAF), 2-aminofl uorene (AF) or N-hydroxy-2-acetylaminofluorene (N-OH-AFF) for 3 hrs resulted in an increase in DNA repair measured as unscheduled DNA synthesis, with N-OH-AAF > AAF > AF. Cytotoxic effects were only seen with N-OH-AAF above 10^–6 M. -Naphthof avone increased the unscheduled DNA synthesis and cytotoxic effects of N-OH-AAF, whereas it decreased DNA repair and the covalent binding of AAF to cellular proteins. In contrast, very little effects of paraoxon were seen on the repair synthesis elicited by AAF, AF or N-OH-AAF. The addition of ascorbate reduced the covalent binding of AAF, the DNA repair synthesis caused by AAF and N-OH-AAF, and the cytotoxic effects of N-OH-AAF. The addition of pentachlorophenol or salicylamide all resulted in similar effects as ascorbate, through reduction of sulfation. Galactosamine, an inhibitor of glucuronidation, and the nucleophile GSH caused no or only minor effects of the activation of AAF, AF or N-OH-AAF as judged from the endpoints tested. These results are consistent with an arylnitrenium ion, a sulfate ester or a free radical as the arylamine metabolite causing cellular DNA damage, whereas the sulfate ester or a radical intermediate may be responsible for the cytotoxic effects of N-OH-AAF.Abbreviations AAF 2-acetylaminofluorene - AF 2-aminofluorene - N-OH-AAF N-hydroxy-2-acetylaminofluorene - cytochrome P-450 a collective term for all forms of the cytochrome P-450 polysubstrate monooxygenase - DMSO dimethyl sulfoxide - HU hydroxyurea - S-9 9000 g supernatants - LDH lactate dehydrogenase - UDS unscheduled DNA synthesis - ANF -naphthoflavone - GSH glutathione - PCP pentachlorophenol - MET metyrapone - PAR paraoxon - DEM dimethylmaleate     

On the distribution of genotoxic factors in various organs of mice treated with cycasin

The distribution of genotoxic factors in various organs of mice treated orally with methylazoxymethanol-beta-D-glycoside (cycasin) was investigated using the DNA-repair host mediated assay. Indicator of genotoxic activity was a pair of streptomycin dependent Escherichia coli strains differing vastly in DNA repair capacity; uvrB/recA vs. uvr+/rec+. The animal-mediated assays were performed by injecting mixtures of the two strains i.v. and orally into mice, which were subsequently treated with the test chemical and from which the differential survival of the indicator bacteria present in several organs was determined. The same strains and selection procedures were also used for assessing the DNA-damaging activity in vitro. In the animal-mediated assays in which cycasin was applied orally, significant effects were observed at doses of 100 and 500 mg/kg body weight. The organ distribution of genotoxic factors in the host animal was as follows: the highest genotoxic activity was observed in the liver, followed by intestine and stomach; a clear effect was also observed in the kidneys and, to a lower extent, in the blood stream and in the lungs at the highest dose administered (500 mg/kg body weight). Under in vitro conditions a marginal genotoxic effect was observed even in the absence of liver homogenate, indicating that the test compound is possible activated (hydrolysed) by the E. coli cells. Therefore the genotoxic activity of cycasin observed in the gastrointestinal tract was not unexpected, since the substance was applied orally, thereby exposing the indicator bacteria in these organs to high levels of unmetabolised compound, especially in the stomach. In the intestine members of the microbial flora probably contribute to the metabolic activation of the test compound. The occurrence of genotoxic factors remote from the gastrointestinal tract shows that the present compound or active metabolites thereof penetrate through the intestinal barrier. The extraordinarily high genotoxic activity observed in the liver suggests that the compound is additionally activated in this organ. In compliance with previous in vitro findings this second activation step might lead to the formation of the highly reactive aldehydic form of methylazoxymethanol (MAMAL) mediated by dehydrogenases. Comparison with carcinogenicity studies indicates a good correlation between the distribution of genotoxic effects as determined in the present studies and the localisation of tumors in various organs of rodents treated with cycasin.     

Evaluation of the cytotoxic,anticancer, and genotoxic activities of Acacia nilotica flowers and their effects on N-methyl-N-nitrosourea-induced genotoxicity in mice

Molecular Biology Reports - In this study, two main research objectives were examined: (1) the cytotoxic and anticancer activities of the aqueous methanol extract from Acacia nilotica flowers on...     

Endocytosis of micro- and nanosized particles in vitro by human dendritic cells

The ability of human dendritic cells (DC) to uptake synthetic micro- and nanosized particles was assessed by flow cytometry and fluorescent microscopy. DCs were differentiated in vitro from blood monocytes in the presence of recombinant cytokines. Further maturation of DC in culture after the addition of maturation factors resulted in the increased expression of HLA-DR and co-stimulatory molecules CD80, CD83, CD86, in comparison with immature DC. Active internalization of Fluoresbrite-YG fluorescent microbeads (0.2 μm) was noted for immature but not mature DCs. The decrease of endocytic activity after DC maturation correlated with the reduced expression of CD209, the surface membrane receptor participating in phagocytosis. Unlike microparticles, the uptake of nanoscale Quantum dots-655 did not depend on the stage of DC maturation and probably was mediated by a different endocytosis mechanism.     

Single and combined genotoxic and cytotoxic effects of two xenobiotics widely used in intensive aquaculture

Several chemicals are used in aquaculture to prevent or to treat disease outbreaks. These substances are mainly administered by two different routes: by prolonged immersion or by mixing into the diet. In the case of intensive aquaculture, the chemicals that are most frequently applied by immersion are formaldehyde (FA) 37% and oxytetracycline (OTC). The first is highly effective against most protozoa, as well as some of the most common parasites such as monogenetic trematodes. OTC presents a large spectrum of antibacterial activities and is used to treat systemic bacterial infections that affect fish. Under therapeutic use, FA (37%) is applied prophylactically at 200ml/m(3), whereas OTC is used curatively at 40g/m(3). The goal of the present study is to assess genotoxic and cytotoxic effects associated with exposure of the European sea bass (Dicentrarchus labrax) to FA37% and OTC under the same conditions as those applied in intensive aquaculture systems. To this end the micronucleus (MN) assay was applied in erythrocytes. Our results show that both tested chemicals present genotoxic and cytotoxic potential following a time-dependent pattern. Remarkably, the combined treatment induces a cumulative effect, which is particularly pronounced after 15 days of exposure. This suggests the critical hazards associated with exposure to FA and OTC when applied or released together.     

Evaluation of genotoxic effects of fumagillin by cytogenetic tests in vivo

Fumagillin is a naturally secreted antibiotic of the fungus Aspergillus fumigatus. It is used in veterinary medicine against microsporidiosis of bees and fish. In this study, the genotoxicity of fumagillin (in the form of fumagillin dicyclohexylamine) was evaluated in mouse bone-marrow cells using the mitotic index (MI), the chromosome aberration (CA) assay, and the micronucleus (MN) test. Fumagillin was administered to BALB/c mice by gavage, at doses of 25, 50, 75 mg/kg body weight (bw), repeated for 7 days at 24-h intervals, with water-sugar syrup as a negative control and cyclophosphamide (40 mg/kg bw) as a positive control. All experimental doses of fumagillin induced a significant decrease (p<0.001) in MI (3.47+/-0.04%, 3.17+/-0.01%, and 2.27+/-0.02%, respectively) in comparison with the negative control (6.00+/-0.01%). Fumagillin significantly (p<0.001) increased the frequency of MN (4.98+/-0.35, 8.45+/-0.57, and 12.02+/-0.37, respectively) over negative control (1.04+/-0.28). Significantly increased frequencies (p<0.01 or p<0.001) of numerical chromosomal aberrations (aneuploidies and polyploidies) and structural chromosomal aberrations such as gaps, breaks, and centric rings were observed at the highest experimental dose of fumagillin (75 mg/kg bw) compared with the negative control. However, with respect to the induction of Robertsonian translocations, both the intermediate (50 mg/kg bw) and highest (75 mg/kg bw) experimental dose caused a significant (p<0.001) increase (7.12+/-0.26 and 9.00+/-0.10, respectively) in comparison with the negative control (0.00+/-0.00). Chromosomes 4 and 19 participated in these Robertsonian translocations. Regarding total cytogenetic changes, a significant increase (p<0.001) was observed in both the intermediate dose group (17.36+/-1.83) and the highest dose group (59.49+/-1.92) compared with the negative control (7.00+/-1.35). These results suggest that fumagillin has genotoxic (clastogenic) potential in mammals in vivo.     

Prevention of cytotoxic effects of arsenic by short-term dietary supplementation with selenium in mice in vivo

Interaction between selenium and arsenic has been used to protect against the genotoxic effects of sodium arsenite through dietary intervention by an equivalent amount (1/10 LD50) of sodium selenite. The two salts were administered by gavaging to laboratory bred Swiss albino mice sequentially and in combination. Cytogenetic endpoints, including chromosomal aberrations (CA) and damaged cells (DC) were recorded 24 h after exposure from chromosome spreads in bone marrow cells. Administration of sodium selenite 1 h before sodium arsenite reduced the clastogenic effects of the latter significantly. The protection was less when the salts were given together and negative when arsenite was given before selenite. Histological changes were recorded. Such reduction of arsenic toxicity through dietary intervention by selenium is of significance in protecting against the widespread toxicity observed in human populations exposed to arsenic through drinking water from contaminated deep tubewells in West Bengal and Bangladesh.     

Effects of nanosized titanium dioxide on the photosynthetic metabolism of fenugreek (Trigonella foenum-graecum L.)

The potential toxicity of nanoparticles in plants is scarce and contradictory. Despite the diversity of research efforts, a detailed explanation of the TiO₂NPS effects in plant photosynthesis is still missing. The present work gives a new approach to examine the impact of the TiO₂NPs on crop production (development and photosynthesis) and plant protection (tolerance and defense systems) in fenugreek (Trigonella foenum graecum L.). Seedlings were assessed in greenhouse trials to estimate the influence of TiO₂NPs on physiological characters for 16 days. They were treated with TiO₂NPs at a size less than 20 nm. The results revealed that there were no significant effects on seedlings growth and biomass of stem, but a decrease in the fresh weight of leaves after TiO₂NPs treatment. Plants treated with 100 mg·L^?1 of TiO₂NPs presented a reduction and chlorosis in leaf area due to a significant decrease in the chlorophyll a and b contents. The highest value of the photosynthetic pigments was recorded at 50 mg·L^?1 of TiO₂NPs. However, the treatment with 100 mg·L^?1 of TiO₂NPs caused a decrease in the levels of chlorophyll a, b and of carotenoids. Both doses of TiO₂NPs induced an accumulation of anthocyanins compared to the control after 16 days of seedling development. A nano-stress significantly decreased the flavonoids level, but increased that of polyphenols compared to control after 16 days of exposure. The decrease in the translocation ratio of flavonoids suggests that many of them contain an enediol group, which suggests that they may act as bidentate ligands for anatase TiO₂NPs. Accordingly, nano-stressed leaves exhibited significantly enhanced GPOX, CAT and APX activity levels. On the contrary, GPOX and CAT activities were reduced substantially in stems treated with 100 mg·L^?1 TiO₂NPs. The accumulation of MDA was found to be higher in stems than in leaves. This could be explained by the accumulation of nanoparticles in different organs; it could be that the stems are the favored targets of nanoparticles. These results underline the necessity for a deeper estimation of nanoparticle ecotoxicity and particularly concerning their interaction with plants.     

In vivo NIRF imaging of tumor targetability of nanosized liposomes in tumor-bearing mice

To optimize tumor targetability of nanosized liposomes for application as drug carriers, various liposomes are prepared by incorporating different amounts (10, 30, and 50?wt%) of cationic, anionic, and PEGylated lipids into neutral lipid. In vivo near-infrared fluorescence images reveal that PEG-PE/PC liposomes display high tumor accumulation in tumor-bearing mice, while large amounts of DOTAP/PC liposomes are rapidly captured in the liver, resulting in poor tumor accumulation. These results demonstrate that optimization of the surface properties of liposomes is very important for their tumor targetability, and that in vivo imaging techniques are useful in developing and optimizing nanosized liposome-based drug carriers.