Silver nanoparticles (AgNPs) of both biologically and chemically origins trigger various physiological and metabolic processes through interaction with plant cells, exerting positive, negative and inconsequential effects. However, their impacts on plant systems must be critically investigated to guarantee their safe application in food chain. In this study, the effects of chemically synthesized (synthetic) AgNPs (sAgNPs) and biologically synthesized (biogenic) AgNPs (bAgNPs) on physiological and biochemical features of Eschscholzia californica Cham were evaluated at different concentrations (0, 10, 25, 50 and 100 mg L⁻¹). Plants exposed to bAgNPs (at 10 and 25 mg L⁻¹) and sAgNPs (at 10 mg L⁻¹) displayed relatively uniform deposition of AgNPs on leaf surface, however, the higher concentration (100 mg L⁻¹) was accompanied by aggregation of AgNPs, resulting in anatomical and physiological disorders. Foliar application of both AgNPs at lower concentrations resulted in significant (P < 0.01) improve in the content of photosynthetic pigments (chlorophylls a, b, a+b, and carotenoids) and total phenolics over the control in a dose-related manner. Leaf relative water content decreased steadily with increasing both sAgNPs and bAgNPs concentrations-with sAgNPs being more inhibitive. Both types of AgNPs at 100 mg L⁻¹ significantly (P < 0.05) increased electrolyte leakage index, level of lipid peroxidation product (malondialdehyde), and leaf soluble sugar content when compared to controls. No significant difference was found on cell membrane stability index among the plants exposed to bAgNPs and sAgNPs at the lowest concentration over the control. Californidine content was significantly (P < 0.01, by 45.1%) increased upon all the bAgNPs treatments (with a peak at 25 mg L⁻¹) relative to control. The obtained extracts from plants treated with bAgNPs at lower concentrations revealed a significant induction of antioxidant capacity (based on DPPH˙ free radical scavenging and ferrous ions-chelating activities) with lower IC₅₀ values compared to the other treatments. Conclusively, bAgNPs at lower concentrations are potent elicitors of pharmaceutically active compounds biosynthesis, which enhance physiological efficiency of E. californica, but at higher concentrations bAgNPs are equally toxic as sAgNPs.

Application of nanopesticides may substantially increase surface attachment and internalization of engineered nanoparticles (ENPs) in food crops. This study investigated the role of stomata in the internalization of silver nanoparticles (Ag NPs) using abscisic acid (ABA)-responsive ecotypes (Ler and Col-7) and ABA-insensitive mutants (ost1-2 and scord7) of Arabidopsis thaliana in batch sorption experiments, in combination with microscopic visualization. Compared with those of the ABA-free control, stomatal apertures were significantly smaller for the Ler and Col-7 ecotypes (p ˂ 0.05) but remained unchanged for the ost1-2 and scord7 mutants, after exposure to 10 μM ABA for 1 h. Generally Ag NP sorption to the leaves of the Ler and Col-7 ecotypes treated with 10 μM ABA was lower than that in the ABA-free control, mainly due to ABA-induced stomatal closure. The difference in Ag NP sorption with and without ABA was less pronounced for Col-7 than for Ler, suggesting different sorption behaviors between these two ecotypes. In contrast, there was no significant difference in foliar sorption of Ag NPs by the ost1-2 and scord7 mutants with and without ABA treatment. Ag NPs were widely attached to the Arabidopsis leaf surface, and found at cell membrane, cytoplasm, and plasmodesmata, as revealed by scanning electron microscopy and transmission electron microscopy, respectively. These results highlight the important role of stomata in the internationalization of ENPs in plants and may have broad implications in foliar application of nanopesticides and minimizing contamination of food crops by ENPs.

Nowadays, the ubiquitous distribution and increasing abundance of P⁺ᴵᴵᴵ in waterbodies have caused serious concerns regarding its bioavailability and potential toxicity. However, our knowledge on these issues is relatively limited. We addressed previously unknown effects of P⁺ᴵᴵᴵ on three dominate algae species i.e. Microcystic aeruginosa (M. aeruginosa), Chlorella pyrenoidesa (C. pyrenoidesa) and Cyclotella. sp in eutrophic waterbodies in China. Remarkable declines in biomass, specific growth rate and Chl-a of algae cells treated with 0.01–0.7 mg/L P⁺ᴵᴵᴵ as sole or an alternative P source were observed, indicating P⁺ᴵᴵᴵ had an inhibitory effect on the algal growth. Besides, the intracellular enzyme activities e.g superoxide dismutase (SOD) and malondialdehyde (MDA) were significantly increased with P⁺ᴵᴵᴵ stress. M. aeruginosa and Cyclotella. sp cells seemed to be more sensitive to P⁺ᴵᴵᴵ toxicity than C. pyrenoidesa since cell membrane suffered more serious stress and destruction. These findings combined, it confirmed P⁺ᴵᴵᴵ could not be utilized as bioavailable P, but had certain toxicity to the tested algae. It indicated that the increased P⁺ᴵᴵᴵ abundance in eutrophic waterbodies would accelerate the algal cell death, which could have a positive effect against algal blooms. Our results provide new insights into assessing the ecological risks of P⁺ᴵᴵᴵ in aquatic environments.

The current study provides an information on the combined effect of pollution with potentially toxic elements (PTEs) and polycyclic aromatic hydrocarbons (PAHs) in hydromorphic soils on the accumulation, growth, functional and morphological-anatomical changes of macrophyte plant, i.e., Phragmites australis Cav., as well as information about their bioindication status on the example of small rivers of the Azov basin. The territory of the lower reaches of the Kagalnik River is one of the small rivers of the Eastern Azov region was examined with different levels of PTEs contamination in soils, where the excess of the lithosphere clarkes and maximum permissible concentrations (MPC) for Mn, Cr, Zn, Pb, Cu, and Cd were found. The features of the 16 priority PAHs quantitative and qualitative composition in hydromorphic soils and P. australis were revealed. The influence of soil pollution on accumulation in P. australis, as well as changes in the morphological parameters were shown. It has been observed that morphometric changes in P. australis at sites experiencing the сontamination and salinity are reflected with the changes in the ultrastructure of plastids, mitochondria, and EPR elements of plant cells. PTEs accumulated in inactive organs and damaged cell structures. At the same time, PAHs penetrated through the biomembranes and violated their integrity, increased permeability, resulted cell disorganization, meristem, and conductive tissues of roots. The nature and extent of the structural alterations found are dependent on the type and extent of pollution in the examined regions and can be utilized as bioindicators for evaluating the degree of soil phytotoxicity characterized by the accumulation of PTE and PAHs.

Graphene oxide (GO) has been widely studied and applied in numerous industrial fields and biomedical fields for its excellent physical and chemical properties. Along with the production and applications of GO persist increasing, the environmental health and safety risk (EHS) of GO has been widely studied. However, previous studies almost focused on the biotoxicity of pristine GO under a relatively high exposure dose, without considering its transformation process within environmental and biological mediums. Meanwhile, its secondary toxicity or synergistic effects have not been taken seriously. Here, two different kinds of artificial lung fluids were adopted to incubate pristine GO to mimic the biotransformation process of GO in the lung fluids. And, we explored that biotransformation within the artificial lung fluids could significantly change the physicochemical properties of GO and could enhance its biotoxicity. To reveal the synergistic effects of GO and toxic metal ions, we uncovered that GO could enhance the intracellular content of metal ions by inhibiting the efflux function of ATP binding cassette (ABC) transporters which are distributed on the cellular membrane, and artificial lung fluids incubation of GO could enhance this synergistic effect. Finally, toxic metal ions induced a series of toxic reactions through oxidative stress response and promoted cell death. Moreover, consistent with the results of in vitro experiments, the lungs of mice exposed to GOs combined with Cd exhibited significant inflammation and oxidative stress compared with Cd treatment alone, and it was more remarkable within the mice which were treated with bio-transformed GOs. In summary, this study explored the impact and mechanism of biotransformation of GO in the lung fluids on the synergistic and secondary effects between GO and metal ions.

Due to the large-scale outbreak of Corona Virus Disease (2019), amounts of disinfecting agents was regularly used in public environments and their potential toxicity towards organisms needed to be appreciated. Thus, one mostly used cationic disinfectant, benzalkonium chlorides (BAC(C12)), was selected to assess its potential toxicity one common cyanobacteria Microcystis aeruginosa (M. aeruginosa) in this study. The aims were to explore the toxic effect and mechanism of BAC (C12) on M. aeruginosa growth within 96 h via morphological, physiological, and the relative and absolute quantification (iTRAQ)-based quantitative proteomics variations. The results found that BAC(C12) significantly inhibited cell density of M. aeruginosa at concentrations from 1 mg/L to 10 mg/L, and the 96-h EC₅₀ value was identified to be 3.61 mg/L. Under EC₅₀ concentration, BAC(C12) depressed the photosynthesis activities of M. aeruginosa exhibited by 36% decline of the maximum quantum yield for primary photochemistry (Fv/Fm) value and denaturation of photosynthetic organelle, caused oxidative stress response displayed by the increase of three indexes including superoxide dismutase (SOD), malondialdehyde (MDA), and the intracellular reactive oxygen species (ROS), and destroyed the integrity of cell membranes demonstrated by TEM images and the increase of ex-cellular substances. Then, the iTRAQ-based proteomic analysis demonstrated that BAC(C12) depressed photosynthesis activities through inhibiting the expressions of photosynthetic protein and photosynthetic electron transport related proteins. The suppression of electron transport also led to the increase of superoxide radicals and then posed oxidative stress on cell. Meantime, the 63.63% ascent of extracellular microcystin production of M. aeruginosa was observed, attributing to the high expression of microcystin synthesis proteins and the damage of cell membrane. In sum, BAC(C12) exposure inhibited the growth of M. aeruginosa mainly by depressing photosynthesis, inducing oxidative stress, and breaking the cell membrane. And, it enhanced the release of microcystin from the cyanobacterial cells via up-regulating the microcystin synthesis proteins and inducing the membrane damage, which could enlarge its toxicity to aquatic species.

Serious environmental pollution of heavy metals has attracted people's attention in recent years and halophiles seem to be potential bioremediation in the controlling of heavy metals contamination. In this study, the adaptive mechanism of halophilic Brachybacterium muris (B. muris) in response to salt stress and its mitigation of copper (Cu) toxicity in hydroponic plants were investigated. The cell morphology was observed using transmission electron microscopy. The cell membrane composition and fluidity were examined by the combination of gas chromatography, gas chromatography-mass spectrometry, ultra-high performance liquid chromatography-mass spectrometry, and fluorescence spectrophotometry. Moreover, the metabolic pathways of B. muris in response to salt stress were analyzed using the prokaryotic transcriptomics approach. A hydroponic co-culture model was further conducted to explore the effects of B. muris on wheat seedlings subjected to Cu toxicity. It was found that B. muris can respond to high osmotic pressure by improving the cell membrane fluidity, altering the cell morphology and cell membrane compositions. The proportion of unsaturated fatty acids, phosphatidylethanolamine, and phosphatidylinositol in B. muris cell membranes increased significantly, while zymosterol, fecosterol, and ergosterol contents decreased under a high salinity situation. Further transcriptomic analysis showed that genes encoding L-glutamate synthase, glutamate ABC transporter ATP-binding protein, and sodium cotransporter were up-regulated, indicating that both the synthesis and transport of glutamate were significantly enhanced under high osmotic pressure. Additionally, B. muris alleviated the inhibitory effect of Cu²⁺ on wheat seedlings' growth, causing a 30.14% decrease in H₂O₂ content and a significant increase of 83.86% and 45.96% in POD activity and GSH content in wheat roots, respectively. The findings of this study suggested that the salt-tolerant B. muris may serve as a promising strategy for improving the bioremediation of metal-contaminated saline water and soils.

In this study, we treated harmful Microcystis aeruginosa cyanobacteria using chitosan-modified nanobubbles. The chitosan-modified nanobubbles (255 ± 19 nm) presented a positive zeta potential (15.36 ± 1.17 mV) and generated significantly (p < 0.05) more hydroxyl radicals than the negatively charged nanobubbles (−20.68 ± 1.11 mV). Therefore, the interaction between the positively charged chitosan-modified nanobubbles and negatively charged M. aeruginosa (−34.81 ± 1.79 mV) was favored. The chitosan-modified nanobubble treatment (2.20 × 10⁸ particles mL⁻¹) inactivated 73.16% ± 2.23% of M. aeruginosa (2.00 × 10⁶ cells mL⁻¹) for 24 h without causing significant cell lysis (≤0.25%) and completely inhibited the acute toxicity of M. aeruginosa toward Daphnia magna. The inactivation was correlated (r² = 0.97) with the formation of reactive oxygen species (ROS) in M. aeruginosa. These findings indicated that the hydroxyl radicals generated by the chitosan-modified nanobubbles disrupted cell membrane integrity and enhanced oxidative stress (ROS formation), thereby inactivating M. aeruginosa. Moreover, the penetration of the chitosan-modified nanobubbles and cell alterations in M. aeruginosa were visually confirmed. Our results suggested that the chitosan-modified nanobubble treatment is an eco-friendly method for controlling harmful algae. However, further studies are required for expanding its practical applications.

The adverse effects of fine atmospheric particulate matter with aerodynamic diameters of ≤2.5 μm (PM₂.₅) are closely associated with particulate chemicals. In this study, PM₂.₅ samples were collected from highway and industry sites in Hangzhou, China, during the autumn and winter, and their cytotoxicity and pulmonary toxicity and endocrine-disrupting potential (EDP) were evaluated in vitro and in vivo; the particulate polycyclic aromatic hydrocarbons (PAHs), phthalate esters (PAEs), and heavy metals were then characterized. The toxicological results suggested that the PM₂.₅ from highway site induced higher cytotoxicity (cell viability inhibition, intracellular oxidative stress, and cell membrane injury) and pulmonary toxicity (inflammatory response (IR) and oxidative stress (OS)) than the samples from industry site, while the PM₂.₅ from industry site exhibited higher EDP (estrogenic and anti-androgenic activity). The cytotoxicity and pulmonary toxicity of PM₂.₅ in the winter were higher than those in the autumn, while no seasonal difference in the endocrine-disrupting potential was observed (p > 0.05). The Pearson correlation analysis between the biological effects and particulate chemicals revealed that the PM₂.₅-induced inflammatory response and oxidative stress were closely associated with the particulate PAHs and heavy metals (Pearson correlation coefficients: rIR, PAHₛ = 0.822–0.988, rIR, ₕₑₐᵥy ₘₑₜₐₗₛ = 0.895–0.971, rOS, PAHₛ = 0.843–0.986, and rOS, ₕₑₐᵥy ₘₑₜₐₗₛ = 0.887–0.933), while particulate di (2-ethylhexyl)phthalate (DEHP) substantially contributed to the EDP of PM₂.₅ (rEDP, DEHP = 0.981). This study indicated that the toxicity and EDP of PM₂.₅ could vary with the surrounding environment and season, which was closely associated with the variations of particulate chemicals. Further studies are needed to clarify the associations between the harmful effects of PM₂.₅ and other contributing factors.

The visible light responsive graphitic nitride (g-C₃N₄) mediated photocatalysis has drawn extensive attention in water treatment field. Carbon doping could improve the photocatalytic activity of g-C₃N₄ in promoting charge separation efficiency, visible-light utilization, etc. In this paper, the g-C₃N₄ (as MC) was modified by barbituric acid (as MCB₀.₀₇) and further treated by reduced graphene oxide (rGO) (as n%GCN) and then applied to inactivate ofloxacin-resistant bacteria (OFLA) under light irradiation at UVA-visible wavelength. The results showed that the n%GCN presented strong photocatalytic activity when the GO mass ratio was 7.5% (as 7.5%GCN). The inactivation efficiencies of OFLA by MC, MCB₀.₀₇, and 7.5%GCN were 5.77 log, 8.48 log, and 8.25 log, respectively, under UVA-visible wavelength (λ > 305 nm), compared to 4.83 log, 5.56 log, and 6.08 log, respectively, within 16 h under visible wavelength (λ > 400 nm). The rGO-doping obviously improved the inactivation efficiency of MCB₀.₀₇ on OFLA under visible wavelength. Furthermore, the photoreactivation and dark repair phenomena of OFLA were examined after MC, MCB₀.₀₇, and 7.5%GCN treatment, respectively, and it was found that all approaches led to permanent damage to OFLA of which the regrowth was not observed after 24–48 h. Based on the quenching test, reactive oxygen species of O₂⁻• and hole (h⁺) exhibited dominant roles in the photocatalytic inactivation of OFLA, which may result in oxidative stress and damage to the cell membrane. This study could shed light on the inactivation of OFLA under visible light radiation by rGO modified g-C₃N₄.