Manufactured silver and gold nanoparticles-induced apoptosis by caspase-pathway in human cell lines

Abstract

Metallic nanoparticles have emerged as an important class of nanomaterials for a wide range of industrial and medical applications. Because of the intensive commercial applications, risk assessment of these nanoparticles is of great importance. In the present study, the human hepatoma and leukemia cells were used to characterize the apoptotic effects of silver nanoparticles (4.7 and 42?nm) and gold nanoparticles (30?nm). Apoptotic cells were identified by chromatin condensation and flow cytometry analysis, using Annexin V/PI, TUNEL and caspase activation assays. Flow cytometry analysis showed that the three metallic nanoparticles induced apoptotic cell death in a concentration and time dependent-manner. Moreover, the three nanoparticles induced activation of caspase-3 and -7 in hepatoma and leukemia cells. Apoptotic effects were stronger after exposure of both cell lines with 4.7?nm silver nanoparticles than those obtained with 42?nm silver and 30?nm gold nanoparticles. In conclusion, silver (4.7 and 42?nm) and gold (30?nm) nanoparticles induced apoptosis in hepatoma and leukemia cells via the caspase dependent pathway. The smaller silver nanoparticles (4.7?nm) had a greater ability to induce apoptosis in both cell lines.     

Cytotoxicity and cell membrane depolarization induced by aluminum oxide nanoparticles in human lung epithelial cells A549

The cytotoxicity of 13 and 22 nm aluminum oxide (Al₂O₃) nanoparticles was investigated in cultured human bronchoalveolar carcinoma-derived cells (A549) and compared with 20 nm CeO₂ and 40 nm TiO₂ nanoparticles as positive and negative control, respectively. Exposure to both Al₂O₃ nanoparticles for 24 h at 10 and 25 µg mL^?1 doses significantly decreased cell viability compared with control. However, the cytotoxicity of 13 and 22 nm Al₂O₃ nanoparticles had no difference at 5–25 µg mL^?1 dose range. The cytotoxicity of both Al₂O₃ nanoparticles were higher than negative control TiO₂ nanoparticles but lower than positive control CeO₂ nanoparticles (TiO₂ < Al₂O₃ < CeO₂). A real-time single cell imaging system was employed to study the cell membrane potential change caused by Al₂O₃ and CeO₂ nanoparticles using a membrane potential sensitive fluorescent probe DiBAC₄(3). Exposure to the 13 nm Al₂O₃ nanoparticles resulted in more significant depolarization than the 30 nm Al₂O₃ particles. On the other hand, the 20 nm CeO₂ particles, the most toxic, caused less significant depolarization than both the 13 and 22 nm Al₂O₃. Factors such as exposure duration, surface chemistry, and other mechanisms may contribute differently between cytotoxicity and membrane depolarization.     

Effect of Zinc Oxide nanoparticles on cellular oxidative stress and antioxidant defense mechanisms in mouse liver

Zinc oxide nanoparticles (ZnO₂), a common ingredient of cosmetics has a huge variety of applications. Previous studies reported oxidative stress mediated toxicity of ZnO₂ nanoparticles on various mammalian cell lines. Although zinc (Zn) is an essential mineral at higher concentrations this metal is toxic. The present study focused on size determination by monitoring changes in activities of antioxidant defense mechanism in response to oxidative stress induced by ZnO₂ nanoparticles using mouse liver tissue homogenates. The study also investigated effects of oxidative stress induced DNA damage by determining formation of 8-OHdG in mouse liver homogenate. A cytotoxicity assay was also carried out in L929 cells to determine cell viability. The results of the study indicated that 50μg/ml of ZnO₂ nanoparticles induced 50% cell death. Alterations in antioxidant parameters and 8-OHdG were also noted. Data showed that there was a concentration-dependent fall in cell viability, decrease antioxidant enzyme levels and increase formation of DNA adduct (8-OHdG) when mouse liver tissue homogenate were exposed to ZnO₂ nanoparticles.     

Effects of three different nanoparticles on bioaccumulation,oxidative stress,osmoregulatory, and immune responses of Carcinus aestuarii

Abstract

In this study, the toxicity of CuO (40?nm), α-Al₂O₃ (40?nm), and α-Fe₂O₃ (20–40?nm) nanoparticles was comparatively investigated on Carcinus aestuarii. Crabs were semi-statically exposed to 1?mg/L of each for 14?days and their accumulation and distribution in tissue and hemolymph, potential oxidative stress mechanism, total hemocyte counts and types, and the osmoregulatory and ionoregulatory responses were determined. The tissue distribution of CuO nanoparticles was hepatopancreas?>?hemolymph?≥?gill?> muscle, for α-Fe₂O₃ gill?>?hepatopancreas?>?muscle?> hemolymph, and for α-Al₂O₃ gill?>?muscle?≥?hemolymph?> hepatopancreas. While α-Al₂O₃ and α-Fe₂O₃ NPs, induced lipid peroxidation and changes in antioxidant enzyme activity in the hepatopancreas tissue, the oxidative damage caused by the CuO nanoparticles was minimal. All three nanoparticles, copper in particular, elicit osmoregulatory and ionoregulatory toxicity at this concentration, due to the inhibition of Na⁺, K⁺-ATPase activity in the gill and depletion of hemolymph and carcass ion concentrations.     

Ecotoxicity of silver nanoparticles on earthworm Eisenia fetida: responses of the antioxidant system,acid phosphatase and ATPase

Ecotoxicity of nanoparticles has received growing attention in recent years. This study investigated the influence of silver nanoparticles (Ag-NP) on earthworm Eisenia fetida. The experiment was performed with five test groups: control (without Ag-NP), 10?nm Ag-NP groups (20, 100 or 500?mg?kg^?1) and positive control (787?mg?kg^?1 AgNO₃). After 14-day acute exposure, activities of various enzymes, including glutathione S-transferase (GST), glutathione reductase (GR), acid phosphatase (AP), and Na⁺, K⁺-ATPase were determined. Effects of Ag-NP with different sizes (10 and 80?nm) were also tested. Data showed that the activity of GR was significantly lower at 500?mg?kg^?1. The activities of AP and Na⁺, K⁺-ATPase were inhibited following the increase of Ag-NP concentration. When treated with Ag-NP with different sizes, activities of AP and Na⁺, K⁺-ATPase of the 10?nm group were significantly lower than the control group, but those of the 80?nm group were similar to the control group. Data indicate that Ag-NP may be harmful to the earthworm E. fetida at 500?mg?kg^?1, and the toxicity of Ag-NP with 10?nm size is greater than 80?nm. In addition, AP and Na⁺, K⁺-ATPase are sensitive biomakers to the effects of Ag-NP.     

4种典型纳米材料对小鼠胚胎成纤维细胞毒性的初步研究

为探讨不同种类纳米材料对原代培养小鼠胚胎成纤维细胞(Mouse embryo fibroblasts,MEF)的毒性效应及作用机制,选择4种典型的纳米材料(纳米碳、单壁碳纳米管、纳米氧化锌、纳米二氧化硅)制备颗粒悬液,设立5个剂量组(5、10、20、50、100μg·mL-1)对BALB/c小鼠MEF细胞进行24、48、72h染毒培养,利用细胞形态学观察和噻唑蓝实验(MTT比色法)检测上述4种纳米材料对MEF细胞活性的影响,同时,测定染毒24h后细胞培养液上清中乳酸脱氢酶(LDH)活性以探讨纳米颗粒对细胞膜完整性的影响.结果显示:1)4种纳米材料均能明显影响MEF细胞的生长形态.染毒24h后,MEF细胞发生不同程度的回缩变形,细胞间隙增大,排列稀疏,胞内颗粒物增多,细胞透明度下降.2)纳米碳、纳米氧化锌、纳米二氧化硅对MEF细胞增殖的抑制作用和对细胞膜完整性的损伤作用均随染毒剂量的升高而增强,具有明显的剂量-效应关系,其半数致死浓度(24h-IC50)分别为21.85、21.94、461.10μg·mL-1;碳纳米管组的剂量-效应之间不呈对数线性关系,未能得出其24h-IC50.3)在不同染毒剂量水平上,4种纳米材料的毒性对比差异显著:低剂量水平上纳米碳与碳纳米管的毒性强于纳米氧化锌和纳米二氧化硅,随着剂量的升高纳米氧化锌的细胞毒性升高最为显著.结果提示,纳米材料能够对MEF细胞造成毒性损伤,破坏细胞膜的完整性可能只是作用途径之一;纳米材料的毒性可能受粒径、形状、化学组成等许多因素的影响.     

Synthesis and antibacterial activity of a Fe3O4–AgCl nanocomposite against Escherichia coli

In this investigation, Fe₃O₄ magnetic nanoparticles (MNPs) were prepared by the alkalinization of an aqueous medium containing ferrous sulfate and ferric chloride. In the next step, a Fe₃O₄–AgCl magnetic nanocomposite was fabricated by the drop-by-drop addition of silver nitrate solution into a NaCl solution containing Fe₃O₄ MNPs. All prepared nanoparticles were characterized by transition electron microscopy (TEM), X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDS). Both particle types varied in size from 2.5 to 20?nm, with an average size of 7.5?nm for Fe₃O₄ MNPs and 12.5?nm for Fe₃O₄–AgCl nanocomposites. The antibacterial effect of the Fe₃O₄ MNPs and fabricated Fe₃O₄–AgCl nanocomposites against Escherichia coli (ATCC 35218) were investigated by conventional serial agar dilution method using the Müller–Hinton Agar medium. The minimum inhibitory concentration was 4?mg?mL^?1 for Fe₃O₄ MNPs and 2?mg?mL^?1 for the Fe₃O₄–AgCl magnetic nanocomposites. Time-kill course assays showed that the Fe₃O₄–AgCl magnetic nanocomposites successfully killed all inoculated bacterial cells during an exposure time of 60?min. The antibacterial activity of recycled Fe₃O₄–AgCl magnetic nanocomposites over four 60?min cycles of antibacterial treatment was further tested against E. coli by the colony-forming unit (CFU) method. The antibacterial efficiency of the nanocomposites was constant over two cycles of antibacterial testing.     

Acute toxicity of copper oxide nanoparticles to Daphnia magna under different test conditions

The acute toxicity of monodispersed 6 nm and <100 nm poly-dispersed copper oxide nanoparticles toward Daphnia magna was assessed using 48 h immobilization tests. CuSO₄ was used as a reference. Four different exposure conditions were tested, to study whether the toxicity of the nanoparticle suspensions changed in a way similar to what is known for dissolved Cu: first in ISO standard test conditions (pH 7.8), second with slight acidity (pH 6.5), third in the presence of citric acid, and fourth in the presence of humic acid. For all four exposure conditions, the toxicity of Cu employed in the three forms followed the same sequence, i.e., CuSO₄ > monodispersed 6 nm CuO ? poly-dispersed CuO. The toxicity of all Cu forms decreased from pH 6.5, ? pH 7.8, > pH 7.8 + citric acid, to ? pH 7.8 + humic acid. This pattern is in agreement with concentrations of Cu²⁺ calculated using the equilibrium model MINTEQ. These findings show that the acute toxicity of copper oxide nanoparticles is governed by test water composition and the chemical species Cu²⁺.     

Hepatic effects of yttrium oxide nanoflowers: in vitro risk evaluation

Yttrium oxide nanoflowers were prepared by a hydrothermal technique, and X-ray diffraction and scanning electron microscopy were used to determine their structures. The cytotoxic and genotoxic potentials of aqueous dispersions of the nanoflowers to cultured primary rat hepatocytes were examined at concentrations up to 500 mg L^?1 for 72 h. Cell viability was determined by monitoring the reduction of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, release of lactate dehydrogenase, and uptake of neutral red. Genotoxicity was assessed by the liver micronucleus assay. Exposure to Y₂O₃ nanoflowers at concentrations lower than 100 mg L^?1 did not lead to any cytotoxicity or genotoxicity. At higher concentrations (200, 400, and 500 mg L^?1), cell viability decreased and induction of micronuclei increased (400 and 500 mg L^?1).     

Responses of oxidative stress,genotoxicity and immunotoxicity as biomarkers in Theba pisana snails dietary exposed to silver nanoparticles

Silver nanoparticles (AgNPs) are now being of a great interest by ecotoxicological researchers. Their potential hazards to humans and other non-target organisms had led to crucial concerns. In this research, white radish leaf extract was used for the green synthesis of AgNPs. UV–Vis spectroscopy, transmission electron microscopy (TEM) and X-ray diffraction (XRD) have been utilised to characterise the biosynthesised AgNPs. Furthermore, the present study aimed to investigate the ecotoxicological effects of 1?mM biosynthesised AgNPs on the land snail, Theba pisana after two weeks of exposure and one week recovery with respect to oxidative stress parameters; lipid peroxidation (LPO), reduced glutathione (GSH), catalase (CAT) and glutathione-S-transferase (GST), cytogenetic parameters; DNA content and micronucleus test, as well as immunological parameters; cell death, phagocytosis, lysosomal membrane stability (LMS), lectins, superoxide anion (O₂^?) generation, phenoloxidase (PO), peroxidase (POD) and haemocyanin (Hc) were examined. AgNPs have been biosynthesised successfully; the UV–vis spectrum exhibited a single and broad absorption band located between 375 and 415?nm, TEM image shows AgNPs formed were nearly spherical in shape with a mean size of 2.18–19.87?nm and the crystalline nature of nanoparticles was confirmed by XRD. After two weeks exposure, the result showed that AgNPs significantly increased LPO level as well as CAT and GST activities, cell death, cell abnormalities and Hc level, whereas, significant decline was found in DNA and GSH contents, phagocytic activity, LMS, lectins, O₂^? generation, POD and PO activities compared to the controls. After a week of recovery, most of the tested biomarkers in AgNP-exposed snails did not completely return to the control levels. The multiple measured parameters could be effectively used as sensitive biomarkers in the risk assessment of contaminants in the terrestrial ecosystem.     

Effects of nanoparticles on Daphnia magna population dynamics

Spherical TiO₂ nanoparticles (npTiO₂) were prepared by controlled hydrolysis of tetraethoxy orthotitanate under a nitrogen atmosphere. ZnO nanoparticles (npZnO) were prepared using hydrothermal methods. The crystal structure, chemical, thermal and morphological properties of npZnO and npTiO₂ were characterised using Fourier Transform Infrared Spectrometer, enery-dispersive X-ray spectroscopy, X-ray diffraction, and scanning electron microscope techniques. The short- and long-term experiments were started with neonates taken from the same culture and laboratory condition. In the acute experiments, npTiO₂, npZnO, and cocktail concentrations were applied. 96h-LC₅₀ values were 1.8, 0.7, and 0.1?mg?L^?1, respectively (p?<?.05). For the chronic experiments, different npTiO₂ concentrations were performed. 21d-LC₅₀ value was 1.0?mgL^?1 (p?<?.05). Morphometry became progressively worse in concentrations of more than 1?mgL^?1 npTiO₂. Neonate and young individuals were more sensitive to death because of their low tolerance. This result was affected by population progeny and growth rates (p?<?.05). While control and 0.5?mgL^?1 npTiO₂ groups were determined as growing population, 1.5 and 2?mgL^?1 npTiO₂ groups had decreased population size as R₀ values. Consequently, the relationships between nanoparticle accumulation within Daphnia magna and its population structure and body morphometry for each concentration were important indicators. Its tolerance level to nanoparticles under laboratory conditions reflected its replacement and behaviour in the ecosystem.     

Color removal efficiency of dyes using nanozerovalent iron treatment

In this study, zerovalent iron nanoparticles (Fe⁰) were synthesized by chemical reduction method using ferric chloride hexahydrate (FeCl₃?·?6H₂O) as a starting material. Sodium borohydride (NaBH₄) was used as a reducer. The synthesized nanozerovalent iron (NZVI) was separated using magnets. The X-ray diffraction pattern of iron (Fe) nanoparticles showed that the presence of intensive diffraction peak at 2θ value of 45.33° from the lattice plane of face-centered cubic Fe unequivocally indicates that the particles are made of pure Fe. The size of the synthesized NZVI was found to be 16.64?nm. The scanning electron micrograph revealed that the particles have a hexagonal and spherical shape in nature. EDX showed the surface atomic distribution and chemical composition of NZVI. The decolorization efficiency rose with increasing concentration of nanoparticles as well as with time. Maximal color removal efficiency was 90.72% when using 0.5?g/100?mL Fe nanoparticle for acridine orange. Data revealed that the function of NZVI on color removal efficiency was statistically significant. The correlation coefficient between NZVI concentration and time showed a strong negative correlation for dyes used in the experiment.     

In vitro cytotoxicity of multi-wall carbon nanotubes on human cell lines

The aim of this study was to evaluate the in vitro toxicity of two multi-wall carbon nanotubes on four different cell lines: human alveolar epithelial (A549) cells, hepatocytes (Hep 3B cells), human embryonic kidney cells, and intestinal (P407 cells) cells. The adverse effects of carbon nanoparticles were analyzed after 24 h incubation with different cell lines using the trypan blue dye exclusion method. Incubation of carbon nanotubes with different cells produced a concentration-dependent inhibition of growth of the cells. The TC₅₀ or IC₅₀ values (toxic concentration 50, i.e., concentration of particles inducing 50% cell mortality) of two nanoparticles were (1) found to be in the range 23.5–30.5 µg mL^?1, and (2) less than that of quartz (known toxic agent, 28.8–66.9 µg mL^?1), indicating the greater cytotoxic effect of carbon nanoparticles than quartz particles.     

纳米二氧化硅对秀丽线虫的毒性作用研究

为探讨二氧化硅纳米颗粒(SiNP)的毒性作用.以微米SiO2和空白做对照,将尺寸为20和60 nm的SiNP分别以0.2,1.0和5.0 g·L-13个浓度对模式生物秀丽隐杆线虫进行染毒.通过第一代和第二代线虫体长、身体弯曲频率、头部摆动频率以及第一代线虫后代数目、世代时间等发育、运动和生殖的相关评价指标,对SiNP毒...     

ZnO纳米粒子通过线粒体通路抑制小鼠光感受器细胞Na~+/K~+-ATP酶表达和活性的作用研究

氧化锌(ZnO)纳米粒子已被发现具有生物毒性,氧化应激被认为是最重要的因素之一。前期实验证实,ZnO纳米粒子能显著减少锰超氧化物歧化酶(Mn SOD)蛋白的表达,降低Mn SOD活性。本文通过检测乳酸脱氢酶(LDH)释放、线粒体活性氧(ROS)水平和膜电位(Δφm)、延迟整流钾电流变化和Na~+/K~+-ATP酶的表达及活性等变化,检测ZnO纳米粒子对小鼠光感受器细胞的细胞毒作用。结果表明,ZnO纳米粒子可显著增强小鼠光感受器细胞中LDH的释放、增加线粒体内ROS水平并下调Δφm、阻断延迟整流钾电流,同时降低Na~+/K~+-ATP酶的表达及活性,从而对小鼠视网膜光感受器细胞产生细胞毒作用,提示ZnO纳米粒子可通过线粒体通路引起氧化应激,从而抑制小鼠光感受器细胞Na~+/K~+-ATP酶表达和活性,产生细胞毒性,导致细胞死亡。本文的研究结果有助于理解ZnO纳米粒子引起细胞毒性的作用机理。     

三种纳米金颗粒对聚合酶链式反应扩增效率和特异性的影响

比较了采用柠檬酸三钠(Trisodium citrate,Na3Ct)还原法、聚乙烯吡咯烷酮(Polyvinylpyrrolidone,PVP)包裹法和巯基丙酸-同型半胱氨酸(Mercaptopropionic Acid-Homocystine,MPA-HCys)包裹法制备的3种纳米金颗粒(Gold nanoparticles,AuNPs)对聚合酶链式反应(Polymerase Chain Reaction,PCR)扩增效率及特异性的影响,以评估金纳米材料表面性质与DNA生物大分子之间的相互作用.实验结果显示,3种AuNPs均能显著提高PCR效率,它们提高PCR效率的能力依次为:Na3 Ct-AuNPs(12 nm)MPA-HCys-AuNPs(12 nm)PVP-AuNPs(4 nm),而且这种增强效应与其浓度和尺寸相关.相同实验条件下,具有相似尺寸大小的Na3Ct-AuNPs比MPA-HCys-AuNPs更能有效提高PCR效率,这说明AuNPs的表面性质也是影响PCR效率的重要因素之一.另外,3种AuNPs均能有效消除竞争性引物对PCR的抑制作用,并且这种作用与其浓度密切相关.上述研究结果表明,具有不同表面性质的3种AuNPs均能有效提高PCR效率和特异性,并且这种作用与其浓度、尺寸和表面性质密切相关.     

Determination of F2-isoprostanes in cultured human lung epithelial cells after exposure to metal oxide and silica nanoparticles by high-performance liquid chromatography/tandem mass spectrometry

The environmental impact of nanotechnology has caused a great concern. Many in vitro studies showed that many types of nanoparticles were cytotoxic. However, whether these nanoparticles caused cell membrane damage was not well studied. F₂-isoprostanes are specific products of arachidonic acid peroxidation by nonenzymatic reactive oxygen species and are considered as reliable biomarkers of oxidative stress and lipid peroxidation. In this article, we investigated the cytotoxicity of different nanoparticles and the degree of cellular membrane damage by using F₂-isoprostanes as biomarkers after exposure to nanoparticles. The human lung epithelial cell line A549 was exposed to four silica and metal oxide nanoparticles: SiO₂ (15 nm), CeO₂ (20 nm), Fe₂O₃ (30 nm), and ZnO (70 nm). The levels of F₂-isoprostanes were determined by using high-performance liquid chromatography/mass spectrometry. The F₂-isoprostanes’ peak was identified by retention time and molecular ion m/z at 353. Oasis HLB cartridge was used to extract F₂-isoprostanes from cell medium. The results showed that SiO₂, CeO₂, and ZnO nanoparticles increased F₂-isoprostanes levels significantly in A549 cells. Fe₂O₃ nanoparticle also increased F₂-isoprostanes level, but was not significant. This implied that SiO₂, CeO₂, ZnO, and Fe₂O₃ nanoparticles can cause cell membrane damage due to the lipid peroxidation. To the best of our knowledge, this is the first report on the investigation of effects of cellular exposure to metal oxide and silica nanoparticles on the cellular F₂-isoprostanes levels.     

ZnO纳米粒子抑制体外小鼠光感受器细胞MnSOD的表达及活性

随着纳米技术的发展,纳米材料在生物医药以及化工中已得到广泛应用。作为一类新型材料,其安全性也日益受到人们的高度关注。为探索氧化锌(ZnO)纳米粒子对小鼠视网膜光感受器细胞的毒性作用,本文通过MTT、荧光染色、流式细胞术、实时荧光定量PCR和酶联免疫吸附试验(ELISA)等技术,分别对经不同浓度ZnO纳米粒子处理的小鼠光感受器细胞活性、活性氧水平、锰超氧化物歧化酶(Mn SOD)的基因和蛋白表达及活性进行了检测。结果表明,ZnO纳米粒子可通过诱导细胞线粒体产生过多的活性氧,降低线粒体膜电位,导致小鼠视网膜光感受器细胞损伤;ZnO纳米粒子能显著减少Mn SOD在mRNA和蛋白质水平的表达,降低Mn SOD活性,加剧氧化应激介导的细胞损伤。因此,氧化应激水平的提高导致了过量的活性氧产生及Mn SOD表达和活性的下降,与ZnO纳米粒子引起的细胞毒性作用有关。     

Role of the necrosis factor-κB pathway in dibutyl phthalate mediated effects on human glioma cells

Abstract

The human glioma cell line U251 was incubated for 12?h and 24?h in medium containing dibutyl phthalate at concentrations of 25?µmol/L and 100?µmol/L. Decreased cell viability and increased oxidative stress show the cytotoxicity of dibutyl phthalate. Nuclear factor-κB and nuclear factor-κB pathway-related proteins were altered, which could be attenuated by vitamin E at 20?µmol/L. Thus, dibutyl phthalate induces cytotoxicity through activation of nuclear factor-κB and vitamin E exerts neuroprotection against dibutyl phthalate-mediated cytotoxicity in vitro.     

Toxicity of cadmium nanoparticles to Bacillus subtilis

The study deals with the toxicological impact of cadmium nanoparticles (Cd NPs) on Bacillus subtilis as a model Gram-positive bacterium. Cadmium oxide (CdO) NPs (～22 nm) and cadmium sulfide (CdS) NPs (～3 nm) were used in this study. Both the NPs were found to inhibit the cell viability of B. subtilis when added to the culture at mid-log phase, the viable cell number declined with increasing concentration of Cd NPs. At mid-log phase, 15 mg L^?1 CdO NPs inhibited growth by ～50%, whereas at 30 mg L^?1 growth completely ceased. Under the same conditions, CdS NPs inhibited growth by ～50% at a concentration of 8 mg L^?1, and at 20 mg L^?1 growth was completely retarded. The cells changed their morphological features to a filamentous form with increasing Cd NPs exposure time, leading to associated with clumping. NPs treated cells when stained with 4′, 6-diamino-2-phenylindole, showed filamentous multinucleated bead structure, suggesting irregularities in cell division. Increasing intracellular oxidative stress due to Cd NPs exposure might be one of the reasons for the cell morphological changes and toxicity in B. subtilis.