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As aluminum nanoparticles (Al-NPs) are widely used in our daily life and various industries, Al-NPs has been becoming an emerging pollution in the environment. The impact of this NP has been attracting more and more attention from the scientific communities. In this review, we systematically summarized the interactions, uptake, and transport of Al-NPs in the plant system. Al-NPs can enter plants through different pathways and accumulate in various tissues, leading to alter plant growth and development. Al-NPs also affected root, shoot, and leaf characteristics as well as changing nutrient uptake and distribution and inducing oxidative stress via excess reactive radical generation, thereby impairing plant defense systems. Additionally, Al-NPs altered gene expression, which involved in various signaling pathways and metabolic processes in plants, that further altered plants susceptible or tolerant to stressors. The review also emphasized the effects of Al-NP size, surface charge, concentration, and exposure duration on plant growth and development. In the future, more research should be focused on mechanisms underlying Al-NPs phytotoxicity and potential risk to humans and off-target species., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Colorectal cancer (CRC) is a major cause of cancer-related deaths in humans, and effective treatments are still needed in clinical practice. Despite significant developments in anticancer drugs and inhibitors, their poor stability, water solubility, and cellular membrane permeability limit their therapeutic efficacy. To address these issues, multifunctional CaCO 3 nanoparticles loaded with Curcumin (Cur) and protein deacetylase (HDAC) inhibitor QTX125, and coated with hyaluronic acid (HA) (CaCO 3 @Cur@QTX125@HA), were prepared through a one-step gas diffusion strategy. Dynamic light scattering (DLS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) showed that CaCO 3 @Cur@QTX125@HA nanoparticles have uniform spherical morphology and elemental distribution, with diameters around 450 nm and a Zeta potential of - 8.11 mV. The controlled release of Cur from the nanoparticles was observed over time periods of 48 h. Cellular uptake showed that CaCO 3 @Cur@QTX125@HA nanoparticles were efficiently taken up by cancer cells and significantly inhibited their growth. Importantly, CaCO 3 @Cur@QTX125@HA nanoparticles showed specific inhibitory effects on CRC cell growth. Encouragingly, CaCO 3 @Cur@QTX125@HA nanoparticles successfully internalized into CRC patient-derived organoid (PDO) models and induced apoptosis of tumor cells. The multifunctional CaCO 3 @Cur@QTX125@HA nanoparticles hold promise for the treatment of CRC., (© 2023. BioMed Central Ltd., part of Springer Nature.)

The development of quantitative analytical methods to assess the heterogeneous distribution and penetration of nanodrugs in solid tumors is of great importance for anticancer nanomedicine. Herein, Expectation-Maximization (EM) iterate algorithm and threshold segmentation methods were used to visualize and quantify the spatial distribution patterns, penetration depth and diffusion features of two-sized hafnium oxide nanoparticles (s-HfO 2 NPs in 2 nm and l-HfO 2 NPs in 50 nm sizes) in mouse models of breast cancer using synchrotron radiation micro-computed tomography (SR-μCT) imaging technique. The three-dimensional (3D) SR-μCT images were reconstructed based on the EM iterate algorithm thus clearly displayed the size-related penetration and distribution within the tumors after intra-tumoral injection of HfO 2 NPs and X-ray irradiation treatment. The obtained 3D animations clearly show that a considerable amount of s-HfO 2 and l-HfO 2 NPs diffused into tumor tissues at 2 h post-injection and displayed the obvious increase in the tumor penetration and distribution area within the tumors at day 7 after combination with low-dose X-ray irradiation treatment. A thresholding segmentation for 3D SR-μCT image was developed to assess the penetration depth and quantity of HfO 2 NPs along the injection sites in tumors. The developed 3D-imaging techniques revealed that the s-HfO 2 NPs presented more homogeneous distribution pattern, diffused more quickly and penetrated more deeply within tumor tissues than the l-HfO 2 NPs did. Whereas, the low-dose X-ray irradiation treatment greatly enhanced the wide distribution and deep penetration of both s-HfO 2 and l-HfO 2 NPs. This developed method may provide quantitative distribution and penetration information for the X-ray sensitive high-Z metal nanodrugs in the cancer imaging and therapy., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The development of nanotechnology has transformed many cutting-edge studies related to single-molecule analysis into nanoparticle (NP) detection with a single-NP sensitivity and ultrahigh resolution. While laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has been successful in quantifying and tracking NPs, its quantitative calibration remains a major challenge due to the lack of suitable standards and the uncertain matrix effects. Herein, we frame a new approach to prepare quantitative standards via precise synthesis of NPs, nanoscale characterization, on-demand NP distribution, and deep learning-assisted NP counting. Gold NP standards were prepared to cover the mass range from sub-femtogram to picogram levels with sufficient accuracy and precision, thus establishing an unambiguous relationship between the sampled NP number in each ablation and the corresponding mass spectral signal. Our strategy facilitated for the first time the study of the factors affecting particulate sample capture and signal transductions in LA-ICP-MS analysis and culminated in the development of an LA-ICP-MS-based method for absolute NP quantification with single-NP sensitivity and single-cell quantification capability. The achievements would herald the emergence of new frontiers cut across a spectrum of toxicological and diagnostic issues related to NP quantification.

With the widespread applications of manufactured nanoparticles (NPs), there are increasing concerns about their potential adverse effects on the environment and living systems. Many studies demonstrated that NPs could significantly affect the growth and development of crop plants. However, knowledge regarding the impacts of NPs on crop quality is rather limited. In this study, the effects of CeO 2 NPs (25, 75, and 225 mg Ce/kg) and CeCl 3 (25 mg Ce/kg) on the nutritional components of soil-cultivated corn and soybean plants were evaluated. Both treatments tended to decrease the dry weight of grain per plant, while only 225 mg/kg CeO 2 NPs on soybean and CeCl 3 on corn showed statistical significance compared with the respective control. CeO 2 NPs at 225 mg/kg significantly decreased the content of starch in the corn kernels by 18.2% but increased total phenols in soybean seeds by 18.4%. Neither CeO 2 NPs nor CeCl 3 significantly affected the contents of minerals in corn kernels except for Zn. However, in the case of soybean, the two treatments tended to decrease the contents of P, Zn, Mn, and Mo but increase the content of S. Overall, the results suggest that CeO 2 NPs and Ce 3+ ions showed similar but not identical effects on corn and soybean plants. CeO 2 NPs affect the nutritional quality of crop plants in a species-dependent manner.

ZIF-8, as an important photoresponsive metal-organic framework (MOF), holds great promise in the field of cancer theranostics owing to its versatile physiochemical properties. However, its photocatalytic anticancer application is still restricted because of the wide bandgap and specific response to ultraviolet light. Herein, we developed lanthanide-doped nanoparticles (LDNPs) coated with Fe/Mn bimetal-doped ZIF-8 (LDNPs@Fe/Mn-ZIF-8) for second near-infrared (NIR-II) imaging-guided synergistic photodynamic/chemodynamic therapy (PDT/CDT). The LDNPs were synthesized by encapsulating an optimal Yb 3+ /Ce 3+ -doped active shell on the NaErF 4 :Tm core to achieve dual-mode red upconversion (UC) and NIR-II downconversion (DC) emission upon NIR laser irradiation. At the optimal doping concentration, the UC and DC NIR-II emission intensities of LDNPs were increased 30.2- and 13.2-fold above those of core nanoparticles, which endowed LDNPs@Fe/Mn-ZIF-8 with an outstanding capability to carry out UC-mediated PDT and NIR-II optical imaging. In addition, the dual doping of Fe 2+ /Mn 2+ markedly decreased the bandgap of the ZIF-8 photosensitizer from 5.1 to 1.7 eV, expanding the excitation threshold of ZIF-8 to the visible light region (∼650 nm), which enabled Fe/Mn-ZIF-8 to be efficiently excited by UC photons to achieve photocatalytic-driven PDT. Furthermore, Fe 2+ /Mn 2+ ions could be responsively released in the tumor microenvironment through degradation of Fe/Mn-ZIF-8, thereby producing hydroxyl radicals (·OH) by Fenton/Fenton-like reactions to realize CDT. Meanwhile, the degradation of Fe/Mn-ZIF-8 endowed the nanosystems with tumor self-enhanced NIR-II imaging function, providing precise guidance for CDT/PDT.

Biomimetic nanozyme with natural enzyme-like activities has drawn extensive attention in cancer therapy, while its application was hindered by the limited catalytic efficacy in the complicated tumor microenvironment (TME). Herein, a hybrid biomimetic nanozyme combines polydopamine-decorated CuO with a natural enzyme of glucose oxidase (GOD), among which CuO is endowed with a high loading rate (47.1%) of GOD due to the elaborately designed hollow mesoporous structure that is constructed to maximize the cascade catalytic efficacy. In the TME, CuO could catalyze endogenous H 2 O 2 into O 2 for relieving tumor hypoxia and improving the catalytic efficacy of GOD. Whereafter, the amplified glucose oxidation induces starvation therapy, and the generated H 2 O 2 and H + enhance the catalytic activity of CuO. Significantly, the tumor-specific chemodynamic therapy (CDT) could be realized when CuO degraded into Cu 2+ in acidic and reductive TME. Furthermore, the photothermal therapy with high photothermal conversion efficiency (30.2%) is achieved under NIR-II laser (1064 nm) excitation, which could reinforce the generation of reactive oxygen species (•OH and •O 2 - ). The TME initiates the biochemical reaction cycle of CuO, O 2 , and GOD, which couples with an NIR-II-induced thermal effect to realize O 2 -promoted starvation and photothermal-chemodynamic combined therapy. This hybrid biomimetic nanozyme enlightens the further development of nanozymes in multimodal cancer therapy.

The impact of CeO 2 nanoparticles (NPs) on plant physiology and soil microcosm and the underlying mechanism remains unclear to date. This study investigates the effect of CeO 2 NPs on plant growth and soil microbial communities in both the rhizosphere of cucumber seedlings and the surrounding bulk soil, with CeCl 3 as a comparison to identify the contribution of the particulate and ionic form to the phytotoxicity of CeO 2 NPs. The results show that Ce was significantly accumulated in the cucumber tissue after CeO 2 NPs exposure. In the roots, 5.3% of the accumulated Ce has transformed to Ce 3+ . This transformation might take place prior to uptake by the roots since 2.5% of CeO 2 NPs was found transformed in the rhizosphere soil. However, the transformation of CeO 2 NPs in the bulk soil was negligible, indicating the critical role of rhizosphere chemistry in the transformation. CeO 2 NPs treatment induced oxidative stress in the roots, but the biomass of the roots was significantly increased, although the Vitamin C (Vc) content and soluble sugar content were decreased and mineral nutrient contents were altered. The soil enzymatic activity and the microbial community in both rhizosphere and bulk soil samples were altered, with rhizosphere soil showing more prominent changes. CeCl 3 treatment induced similar effects although less than CeO 2 NPs, suggesting that Ce 3+ released from CeO 2 NPs contributed to the CeO 2 NPs induced impacts on soil health and plant physiology., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

The time-course association of soil physicochemical properties and fate of CeO 2 nanoparticles (NPs) is not well understood. This study for the first time investigated the dissolution and retention of CeO 2 NPs (<25 nm) during soil short-term (6 h) and long-term (30 d) aging processes with dynamic redox conditions. Under the additional reductant-induced initial reductive condition, theoretically, up to 220‰ of Ce(IV) was temporarily reductively dissolved within 10 min, accompanied by a slow retention process (180 min) of Ce species in soil solutions. Conversely, the dissolution and slow retention of Ce species were not significant in soil solutions without added reductant. X-ray absorption near edge spectroscopy (XANES) shows that most of Ce species were present as Ce(IV) (94.0%-97.8%) in all soils after a long-term aging process. These results indicate that the soil dynamic redox conditions induced by oxidant/reductant intrinsically determined the different time-course dissolution and retention of CeO 2 NPs, highlighting the occasional reductive condition in soil solution that may contribute to the migration and diffusion of Ce species. The time-course study should be also adopted to develop a comprehensive understanding of the nano-soil interactions.

Quantitatively studying the biodistribution and transformation of nanomaterials is of great importance for nanotoxicological evaluation. Recently, laser ablation inductively coupled plasma mass spectrometry has been employed to distinguish nanoparticles (NPs) with their dissolved ions in biological samples. The principle of the proposal is based on a hypothesis that the intact NPs sampled by laser ablation will generate discrete sharp pulses of signals in ICP-MS measurement, being totally different from the continuous, relatively lower signals generated by ions. However, it is still a controversy whether NPs could maintain their intactness during the laser ablation. This work found a way to exactly determine the number of NPs sampled for each LA-ICP-MS measurement. It made possible to reveal the signal profile of a single NP in LA-ICP-MS analysis. The results suggest that AuNR, AgNP and TIO₂ NP were broken into much smaller secondary NPs during the laser ablation, therefore generating continuous signals in the analyzer. There was a certain probability that the fragmentation of large-sized NP or multiple NPs by laser ablation was not sufficient, leaving some NPs unbroken or some secondary NPs with relatively large sizes to generate discrete pulses of signals in the analyzer. When the intactness of NPs during laser ablation cannot be assured, it is impossible to determine the attribution of mass spectrum signals. These findings compromise the reliability of distinguishing NPs from their dissolved ions by LA-ICP-MS.

Phytotoxicity of nanoceria (nCeO 2 ) has been reported, but there are few studies on how to reduce its phytotoxicity. In the present study, we modified nCeO 2 with two organophosphates (nCeO 2 @ATMP and nCeO 2 @EDTMP) and compared their toxicity to lettuce with that of uncoated nCeO 2 . The results showed that bare nCeO 2 significantly inhibited the root growth of lettuce, leading to oxidative damages and root cell death. In contrast, after surface modification, the toxicity of nCeO 2 @ATMP to lettuce was weakened, while nCeO 2 @EDTMP was nontoxic to lettuce. It was found that the surface properties of the modified materials have been changed, resulting in sharp decreases in their bioavailability. Although nCeO 2 with and without surface coatings were all transformed when interacting with plants, the absolute contents of Ce(III) in roots treated with modified nCeO 2 decreased significantly, which may be the main reason for the reduction of toxicity. This study indicates that it is feasible to reduce the phytotoxicity of nanomaterials through surface coating., (Copyright © 2021 Elsevier B.V. All rights reserved.)

This study demonstrates the development of topotecan (TCN) loaded thermosensitive nanocargos (TCN-TS-NC) for intramuscular (IM) administration with enhanced antitumor activity. In this regards, TCN loaded temperature dependent solid lipid nanoparticles (SLNs) were prepared with micro-emulsion method, which were then incorporated into temperature sensitive poloxamer solution to develop TCN-TS-NC. The particle size, entrapment efficiency (%EE), zeta potential and transmission electron microscopy (TEM) analysis of the TCN-TS-NC were performed. Moreover, the inject-ability, release pattern, apoptosis, cellular uptake, pharmacokinetics and antitumor studies of the TCN-TS-NC were attained and compared with TCN solution and TCN-Emulgel (poloxamer solution containing TCN). At room temperature, the TCN loaded SLNs were solid and poloxamer solution remains liquid, however, TCN loaded SLNs melted to liquid and Emulgel converted into gel from, at body temperature, resulting controlled release of the incorporated drug. The TCN-TS-NC showed enhanced cellular uptake and better apoptosis. Similarly, it reduces C max and sustained its level for a significantly longer time in rats, as compared to the TCN-Emulgel and TCN solution. Moreover, a significantly improved antitumor activity was observed in TCN-TS-NC treated tumor bearing athymic nude mice when compared with the control, TCN solution and TCN-Emulgel applied mice. Thus, the TCN-TS-NC system showed control release of the drug with no initial fast effect. Furthermore, it enhanced the antitumor activity of TCN with comparatively no toxicity. It is therefore concluded that TCN-TS-NC could be a potentially more suitable drug delivery system for the delivery of TCN., (Copyright © 2021 The Authors. Published by Elsevier B.V. All rights reserved.)

Dendritic cell-based immunotherapy, in which the antigen is effectively delivered to dendritic cells and then the dendritic cells stimulated by the antigen migrate to draining lymph nodes (DLNs) to induce the CD8 + T-cell immune response, shows great promise for tumor immunotherapy. In this study, we used coassembled nanoparticles formed by Trp2 antigen and the conjugates of short-chain poly(ethylene glycol) (PEG) and pyropheophorbide-A (PPa) (Trp2/PPa-PEGm) to deliver Trp2 to DCs. Intrinsically self-chelating 64 Cu of coassemblies could be used to sensitively image the migration of DCs in vivo by positron emission tomography (PET) imaging. The coassemblies of the Trp2 antigen were efficiently engulfed by DCs without causing DC cytotoxicity in vitro and induced DC maturation. After injection of DCs labeled by coassemblies of the Trp2 antigen, the homing of DCs to DLNs in vivo could be sensitively observed by PET imaging. The C57BL/6 mice injected with DCs containing the Trp2/PPa-PEGm NP showed antigen-specific immune responses including enhanced interferon-γ (IFN-γ) production, splenocyte proliferation, and percentage of IFN-γ-secreting CD8 + T cells. In addition, C57BL/6 mice inoculated with B16-F10 tumor cells showed delayed tumor growth after immunization with the Trp2/PPa-PEGm NP-labeled DC vaccine and enhanced infiltration of CD8 + T cells in tumors.

This study compared the impact and uptake of root-administered CeO 2 nanoparticles (NPs) in rice growing under flooded and aerobic soil conditions, which are two water regimes commonly used for rice cultivation. CeO 2 NPs at 100 mg/kg improved photosynthesis and plant growth by reducing the oxidative damage and enhancing plant tolerance to stress, while a higher concentration (500 mg/kg) of CeO 2 NPs negatively affected plant growth. More significant effects were observed under the flooded condition than under the aerobic condition. CeO 2 NPs of 100 and 500 mg/kg resulted in 78% and 70% higher accumulation of Ce in shoots under the flooded condition compared to the aerobic condition. CeO 2 NPs partially transformed to Ce(III) species in soils and plants under both conditions. A higher extent of transformation under the flooded condition, which was partly attributed to the lower soil pH and redox potential under the flooded condition, leads to higher plant uptake of Ce. A higher extent of transformation in rhizosphere soil was observed. A higher plant transpiration rate (TR) under flooded conditions resulted in a higher accumulation of CeO 2 species in shoots. This study, for the first time, reported that water regimes influenced the biotransformation of CeO 2 NPs and their uptake and impact in rice plants.

2,4-dichlorophenol (2,4-DCP) is a typical chlorophenol that has been widely used in industrial production and caused serious pollution to the environment. In this study, the performance of Fe/Ni bimetallic nanoparticles supported on polystyrene cation exchange resin (Fe/Ni-D072) to remove 2,4-DCP was evaluated. The effects including the doping amount of Ni, the dosage of Fe/Ni-DCP, the initial concentration of 2,4-DCP, and pH value of the solution on the removal efficiency were also investigated. The results showed that when the initial concentration of 2,4-DCP was 20 mg/L and pH = 7.3, 90% of 2,4-DCP could be dechlorinated by Fe/Ni-D072 (Ni% = 30 wt%, dosage: 6.7 g/L) after 12 h reaction. The dechlorination process followed a pseudo-first-order model, and the reaction constant was 0.252 h -1 . In addition, the effects of humic acid and common coexisting ions on dechlorination were studied. The results showed that humic acid with a low concentration (5 mg/L) and CO 3 2- restrained the degradation of 2,4-DCP. The dechlorination products of 2,4-DCP were identified by HPLC and the result showed phenol was the main product with a slight amount of 2-CP as the dechlorination intermediate, and 4-CP was barely detected. These results suggest that Fe/Ni-D072 was a promising catalytic material for the removal of chlorophenol and has great application prospects in groundwater remediation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

As increasing application of nanoparticles, nanoparticles have been becoming a new emerging environmental pollution that attracts a lot of attention from the scientific community and also regulatory agents. In the past decade, studying the toxicity and environmental impacts of nanoparticles is becoming a hot research field and more and more researches have been published using both plant and animal system. In this chapter, using oxidized metal nanoparticles as an example, we introduce a detailed protocol for performing research on biochemical and physiological toxicity of nanoparticles in plant. We employ a hydroponics system to study phytotoxicity of nanoparticles, which makes it easier to study the impact of nanoparticles. In this chapter, we majorly focus on plant respiration and photosynthesis, root vigor as well as oxidative stress. Oxidative stress is one major physiological response to different environmental pollution, in which we present a detailed method for detecting free radical oxygen species as well as the major molecules and enzymes associating with oxidative stress, including SOD and POD. Although we introduce the methods using cotton as an example, the protocols presented in this chapter can be used almost any plant species to test the biochemical and physiological toxicity of an environmental pollution.

Reactive oxygen species (ROS)-based therapeutic modalities including chemodynamic therapy (CDT) and photodynamic therapy (PDT) hold great promise for conquering malignant tumors. However, these two methods tend to be restricted by the overexpressed glutathione (GSH) and hypoxia in the tumor microenvironment (TME). Here, we develop biodegradable copper/manganese silicate nanosphere (CMSN)-coated lanthanide-doped nanoparticles (LDNPs) for trimodal imaging-guided CDT/PDT synergistic therapy. The tridoped Yb 3+ /Er 3+ /Tm 3+ in the ultrasmall core and the optimal Yb 3+ /Ce 3+ doping in the shell enable the ultrabright dual-mode upconversion (UC) and downconversion (DC) emissions of LDNPs under near-infrared (NIR) laser excitation. The luminescence in the second near-infrared (NIR-II, 1000-1700 nm) window offers deep-tissue penetration, high spatial resolution, and reduced autofluorescence when used for optical imaging. Significantly, the CMSNs are capable of relieving the hypoxic TME through decomposing H 2 O 2 to produce O 2 , which can react with the sample to generate 1 O 2 upon excitation of UC photons (PDT). The GSH-triggered degradation of CMSNs results in the release of Fenton-like Mn 2+ and Cu + ions for • OH generation (CDT); simultaneously, the released Mn 2+ ions couple with NIR-II luminescence imaging, computed tomography (CT) imaging, and magnetic resonance (MR) imaging of LDNPs, performing a TME-amplified trimodal effect. In such a nanomedicine, the TME modulation, bimetallic silicate photosensitizer, Fenton-like nanocatalyst, and NIR-II/MR/CT contrast agent were achieved "one for all", thereby realizing highly efficient tumor theranostics.

Plants can play important roles in overcoming selenium (Se) deficiency and Se toxicity in various regions of the world. Selenite (SeIV), selenate (SeVI), as well as Se nanoparticles (SeNPs) naturally formed through reduction of SeIV, are the three main Se species in the environment. The bioaccumulation and transformation of these Se species in plants still need more understanding. The aims of this study are to investigate the phytotoxicity, accumulation, and transformation of SeIV, SeVI and SeNPs in garlic, a relatively Se accumulative plant. The spatial distribution of Se in the roots were imaged using synchrotron radiation micro-focused X-ray fluorescence (SR-μXRF). The chemical forms of Se in different plant tissues were analyzed using synchrotron radiation X-ray absorption spectroscopy (SR-XAS). The results demonstrate that 1) SeNPs which has the lowest phytotoxicity is stable in water, but prone to be converted to organic Se species, such as C-Se-C (MeSeCys) upon uptake by root. 2) SeIV is prone to concentrate in the root and incorporated into C-Se-C (MeSeCys) and C-Se-R (SeCys) bonding forms; 3) SeVI with the lowest transformation probability to organic Se species has the highest phytotoxicity to plant, and is much easier to translocate from root to leaf than SeNPs and SeIV. The present work provides insights into potential impact of SeNPs, selenite and selenate on aquatic-plant ecosystems, and is beneficial for systematically understanding the Se accumulation and transformation in food chain., (Copyright © 2019 Elsevier Inc. All rights reserved.)

In this study, comparative effects of foliar application of ceria nanoparticles (NPs) and Ce 3+ ions on common bean plants were investigated. Soil grown bean seedlings were exposed to ceria NPs and Ce 3+ ions at 0, 40, 80, and 160 mg Ce·L -1 every other day at the vegetative growth stage for 17 d. The plants were harvested 47 d after the last treatment. Performed analyses involved growth, physiological and biochemical parameters of the plants and nutritional quality of the pods. Ceria NPs at 40 mg Ce·L -1 increased dry weight of the plants by 51.8% over the control. Neither ceria NPs nor Ce 3+ ions significantly affected other vegetative growth parameters. Pod yields and nutrient contents except for several mineral elements were also not significantly different among groups. Compared to control, pods from ceria NPs at 80 mg Ce·L -1 had significantly less S and Mn. At 40 and 80 mg Ce·L -1 , ceria NPs reduced pod Mo by 27% and 21%, while Ce 3+ ions elevated Mo contents by 20% and 18%, respectively, compared with control. Ce 3+ ions at 80 and 160 mg Ce·L -1 significantly increased pod Zn by 25% and 120%, respectively, compared with control. At the end of the experiment, Ce 3+ ions at 40, 80, and 160 mg Ce·L -1 increased contents of malondialdehyde (MDA) by 46%, 65%, and 82% respectively as compared with control. While ceria NPs led to a significant increase of MDA level only at the highest concentration. X-ray absorption near edge structure (XANES) analysis of the leaf samples revealed that both ceria NPs and Ce 3+ ions kept their original chemical species after foliar applications, suggesting the observed effects of ceria NPs and Ce 3+ ions on the plants were probably due to their nano-specific properties and ionic properties respectively., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

The physiochemical properties of nanoparticles (NPs), including surface charge, will affect their uptake, transformation, translocation, and final fate in the environment. In this study, we compared the phytoxoxicity and transport behaviors of nano CeO 2 (nCeO 2 ) functionalized with positively charged (Cs-nCeO 2 ) and negatively charged (PAA-nCeO 2 ) coatings. Cucumber seedlings were hydroponically exposed to 0-1000 mg/L of Cs-nCeO 2 and PAA-nCeO 2 for 14 days and the contents, distribution, translocation, and transformation of Ce in plants were analyzed using inductively coupled plasma mass spectrometry, micro X-ray fluorescence (μ-XRF), and X-ray absorption near-edge spectroscopy (XANES), respectively. Results showed that the seedling growth and Ce contents in plant tissues were functions of exposure concentrations and surface charge. Cs-nCeO 2 was adsorbed strongly on a negatively charged root surface, which led to significantly higher Ce contents in the roots and lower translocation factors of Ce from the roots to shoots in Cs-nCeO 2 group than in PAA-nCeO 2 group. The results of μ-XRF showed that Ce elements were mainly accumulated at the root tips and lateral roots, as well as in the veins and at the edge of leaves. XANES results revealed that the proportion of Ce(III) was comparable in the plant tissues of the two groups. We speculated that Cs-nCeO 2 and PAA-nCeO 2 were partially dissolved under the effect of root exudates, releasing Ce 3+ ions as a result. Then, the Ce 3+ ions were transported upward in the form of Ce(III) complexes along the vascular bundles and eventually accumulated in the veins. The other portion of Cs-nCeO 2 and PAA-nCeO 2 entered the roots through the gap of a Casparian strip at root tips/lateral roots and was transported upward as intact NPs and finally accumulated at the edge of the blade. This study will greatly advance our information on how the properties of NPs influence their phytotoxicity, uptake, and subsequent trophic transfer in terrestrial food webs.

Ceria nanoparticles (nanoceria) have been used as a fuel-borne catalyst, and are emitted in the particulate phase in the diesel exhaust. To evaluate the potential health risks of airborne nanoceria, the pulmonary and systemic consequences of nanoceria to ICR mice were studied under repeated transnasal instillation. Two different size nanoceria (7-nm and 25-nm) were chose, representing the nanoceria mostly used as fuel additives and the combustion products of the very nanoceria, respectively. As the first target organ of nanoceria, the lungs suffered serious damages manifested in the results of their biochemical and pathological examinations. The results demonstrated the penetration of nanoceria through air-blood barrier after the lung burden. Nanoceria were further transferred to the secondary target organs, mainly the liver and spleen. Nanoceria could also arrive at the central neural system via olfactory nerve pathway. The systemic accumulation of nanoceria finally triggered lipid peroxidation in multiple organs. Generally, the smaller nanoceria induced more severe pulmonary damage but similar systemic toxicity when compared with the larger one. These findings imply that using nanoceria as diesel fuel catalyst may cause health concerns. Additional studies are warranted to investigate the pulmonary and systemic health consequences of nanoceria additive to diesel fuel.

Thorium (Th) is a natural radioactive element present in the environment and has the potential to be used as a clean nuclear fuel. Relatively little is known about the aquatic toxicity of Th, especially in nanoparticulate form, which may be the main chemical species of Th in the natural waters. In this study, impacts of ThO 2 nanoparticles (NPs) with two different sizes (52 ± 5 nm, s-ThO 2 vs. 141 ± 6 nm, b-ThO 2 ) on a green alga Chlorella pyrenoidosa (C. pyrenoidosa) were evaluated. Results indicated that C. pyrenoidosa was more sensitive to s-ThO 2 (96-h EC 30  = 64.1 μM) than b-ThO 2 (96-h EC 30  = 100.2 μM). Exposure to 200 μM of ThO 2 NPs reduced the chlorophyll-a and chlorophyll-b contents of the algal cells. At 96 h, SEM and TEM showed that more agglomerates of s-ThO 2 than those of b-ThO 2 were attached onto the surface of algal cells. Reactive oxygen species (ROS) generation and membrane damage were induced after the attachment of high concentrations of ThO 2 NPs. The heteroagglomeration between ThO 2 NPs and algal cells and increased oxidative stress might play important roles in the toxicity of ThO 2 NPs. To the best of our knowledge, this is the first report on aquatic toxicity of ThO 2 NPs., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The trophic transfer and transformation of CeO 2 nanoparticles (NPs) through a simulated terrestrial food chain were investigated using a radiotracer technique and X-ray absorption near edge structure (XANES). Radioactive 141 CeO 2 NPs were applied to head lettuce ( Lactuca sativa), treated via root exposure in its potting soil (5.5 or 11 mg/plant) for 30 days or foliar exposure (7.2 mg/plant, with half of the leaves treated and the other half not) for 7 days. Subsequently, two groups of land snails ( Achatina fulica) were exposed to 141 Ce via either a direct (i.e., feeding on the lettuce leaves with 141 Ce-contaminated surfaces) or an indirect/trophic (i.e., feeding on the lettuce leaves with systemically distributed 141 Ce) route. To evaluate the influence of exposure routes, the Ce contents of the lettuce, snail tissues, and feces were determined by radioactivity measurements. The results show that both assimilation efficiencies (AEs) and food ingestion rates of Ce are greater for the trophic (indirect) exposure. The low AEs indicate that the CeO 2 NPs ingested by snails were mostly excreted subsequently, and those that remained in the body were mainly concentrated in the digestive gland. XANES analysis shows that >85% of Ce was reduced to Ce(III) in the digestive gland under direct exposure, whereas Ce in the rest of the food chain (including feces) was largely in its original oxidized (IV) state. This study suggests that CeO 2 NPs present in the environment may be taken up by producers and transferred to consumers along food chains and trophic transfer may affect food safety.

Clarifying hydrogen evolution and identifying the active hydrogen species are crucial to the understanding of the electrocatalytic hydrodechlorination (EHDC) mechanism. Here, monodisperse palladium nanoparticles (Pd NPs) are used as a model catalyst to demonstrate the potential-dependent evolutions of three hydrogen species, including adsorbed atomic hydrogen (H* ads ), absorbed atomic hydrogen (H* abs ), and molecular hydrogen (H 2 ) on Pd NPs, and then their effect on EHDC of 2,4-dichlorophenol (2,4-DCP). Our results show that H* ads , H* abs , and H 2 all emerge at -0.65 V (vs Ag/AgCl) and have increased amounts at more negative potentials, except for H* ads that exhibits a reversed trend with the potential varying from -0.85 to -0.95 V. Overall, the concentrations of these three species evolve in an order of H* abs < H* ads < H 2 in the potential range of -0.65 to -0.85 V, H* ads < H* abs < H 2 in -0.85 to -1.00 V, and H* ads < H 2 < H* abs in -1.00 to -1.10 V. By correlating the evolution of each hydrogen species with 2,4-DCP EHDC kinetics and efficiency, we find that H* ads is the active species, H* abs is inert, while H 2 bubbles are detrimental to the EHDC reaction. Accordingly, for an efficient EHDC reaction, a moderate potential is desired to yield sufficient H* ads and limit H 2 negative effect. Our work presents a systematic investigation on the reaction mechanism of EHDC on Pd catalysts, which should advance the application of EHDC technology in practical environmental remediation.

Dendritic cells (DC) and tumor cell fusion vaccine (DC/tumor cell fusion vaccine) is considered an effective approach in cancer biotherapy. However, its therapeutic effects in early clinical trials have been suboptimal partially due to the immunosuppressive tumor environment. In this study, we used nanoparticles of folate (FA)-modified chitosan, a non-viral vector capable of targeting tumor cells with high expression of FA receptors. FA-chitosan nanoparticles were used as biological carriers for the expression plasmid of the mouse interferon-induced protein-10 (mIP-10) gene, a potent chemoattractant for cytotoxic T cells. The combination of FA-chitosan/mIP-10 and DC/tumor cell fusion vaccine against hepatocellular carcinoma (HCC) effectively inhibited the growth of implanted HCC tumors and prolonged the survival of mice. The combination therapy significantly reduced myeloid-derived suppressor cells (MDSC) in mouse spleen, local tumor, and bone marrow while increasing tumor-specific IFN-γ responses. Furthermore, the combination therapy significantly inhibited tumor cell proliferation while promoting their apoptosis. Taken together, our data illustrate that the mIP-10 enhances the anti-tumor effect of DC/tumor cell fusion vaccine by alleviating the immunosuppressive tumor environment., Competing Interests: Competing Interests: The authors have declared that no competing interest exists.

Background: Adoptive immunotherapy with cytotoxic T lymphocytes (CTLs) has great potential for the treatment of some malignant cancers. Therefore, augmenting the responses of tumor-specific CTLs is significant for the adoptive immunotherapy of melanoma. This study aimed to investigate the anti-tumor response of a combination therapy employing folate-modified chitosan nanoparticles containing IP-10 (interferon-γ-inducible protein-10) plus melanoma TRP2-specific CD8(+)CD28(+) T cells., Methods: We prepared folate-modified chitosan nanoparticles containing the mouse IP-10 gene (FA-CS-mIP-10), and induced melanoma TRP2-specific CD8(+)CD28(+) T cells by co-culturing them with artificial antigen-presenting cells. B16-bearing mice were treated with FA-CS-mIP-10, melanoma TRP2-specific CD8(+)CD28(+) T cells, a combination of both, and the saline control. Tumor volumes and the survival time of mice were recorded. The proportion of myeloid-derived suppressor cells (MDSCs) infiltrating the tumor microenvironment and regulatory T cells (Tregs) in the spleen was analyzed by flow cytometry. We also detected the proliferation and angiogenesis of tumors by immunohistochemistry and apoptosis by TUNEL., Results: The combination therapy inhibited the progression of melanoma in vivo. Compared with other treatments, it more efficiently inhibited tumor growth and increased the survival time of mice. After treatment with combination therapy, the proportion of MDSCs and Tregs decreased, while the percentage of CXCR3(+)CD8(+) T cells increased. Furthermore, combination therapy inhibited proliferation and promoted apoptosis of tumor cells and significantly inhibited tumor angiogenesis in vivo., Conclusion: We describe a novel strategy for improving the anti-tumor response of CD8(+)CD28(+) CTLs by combining them with FA-CS-mIP-10 nanoparticles.

Cerium oxide nanoparticles (CeO2 NPs) have been found to be partly biotransformed from Ce(IV) to Ce(III) in plants, yet the transformation process and mechanism are not fully understood. Here, we try to clarify the specific site and necessary conditions for the transformation of precipitated CeO2 NPs in hydroponic cucumber plants. Three different treatment modes were adopted according to whether the NPs were incubated with roots all the time or not. Results showed that exposure modes significantly affect the translocation and transformation of CeO2 NPs. In the normal exposure mode, Ce was present as a Ce(IV) and Ce(III) mixture in the roots and shoots, and the proportion of Ce(III) in the shoots was enhanced obviously with the increase of exposure time. The results of short-time incubation and petiole exposure modes suggested that CeO2 NPs could not be reduced within a short incubation time (3 h) or be further reduced inside the plant tissues. It was deduced that root surfaces are the sites, and the physicochemical interaction between the NPs and root exudates at the nanobio interface is the necessary condition for the transformation of CeO2 NPs in plant systems. These results will contribute to understanding the transformation mechanism of CeO2 and other metal-based NPs and properly evaluate their ecological effects.

Highly charged nanoparticles of a conjugated polyelectrolyte brush were used to sense the human α-fetoprotein (AFP) by observing selective superquenching in several minutes. The unique property of nanoparticles that the self-aggregation causes an unchanged or enhanced fluorescence can reduce the interference from non-target substance significantly.

Transformation is a critical factor that affects the fate and toxicity of manufactured nanoparticles (NPs) in the environment and living organisms. This paper aims to investigate the effect of phosphate on the transformation of CeO2 NPs in hydroponic plants. Cucumber seedlings were treated with 2000 mg/L CeO2 NPs in nutrient solutions with or without adding phosphate (+P or -P) for 3 weeks. Large quantities of needle-like CePO4 was found outside the epidermis in the +P group. While in the -P group, CePO4 only existed in the intercellular spaces and vacuole of root cells. X-ray absorption near edge spectroscopy (XANES) indicates that content and percentage of Ce-carboxylates in the shoots of -P group (418 mg/kg, 67.5%) were much higher than those in the +P group (30.1 mg/kg, 21%). The results suggest that phosphate might influence the transformation process of CeO2 NPs in plants and subsequently their ultimate fate in the ecosystem., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Species-specific differences in the toxicity of manufactured nanoparticles (MNPs) have been reported, but the underlying mechanisms are unknown. We previously found that CeO2 NPs inhibited root elongation of head lettuce, whereas no toxic effect was observed on other plants (such as wheat, cucumber and radish). In this study, interactions between Lactuca plants and three types of CeO2 NPs (lab-synthesized 7 and 25 nm CeO2 NPs, and a commercial CeO2 NPs) were investigated. It was found that CeO2 NPs were toxic to three kinds of Lactuca genus plants and different CeO2 NPs showed different degrees of toxicity. The results of X-ray absorption near edge fine structure indicate that small parts of CeO2 NPs were transformed from Ce(IV) to Ce(III) in roots of the plants that were treated with CeO2 NPs during the seed germination stage. But the high sensitivity of Lactuca plants to the released Ce(3+) ions caused the species-specific phytotoxicity of CeO2 NPs. Differences in sizes and zeta potentials among three types of CeO2 NPs resulted in their different degrees of biotransformation which accounted for the discrepancy in the toxicity to Lactuca plants. This study is among the few, and may indeed the first, that addresses the relation between the physicochemical properties of nanoparticles and its species-specific phytotoxicity.

Ceria nanoparticles (nano-ceria) are widely used for various applications such as catalytic converters for automobile exhaust, ultraviolet absorber, and electrolyte in fuel cells. Their potential impacts on the environment and human health have also drawn people's attention. The present study was designed to explore the pulmonary toxicity of nano-ceria in mice after an acute intratracheal instillation. CD-1 mice were exposed to 0.04, 0.4, 4 and 40 microg nano-ceria (corresponding to 10, 100, 1000 and 10000 times of the maximum exposure dose, respectively) and sacrificed at 1, 7, and 28 d post-exposure. Lung injury was assessed by bronchoalveolar ravage fluid (BALF) analysis, cell counts, biochemical analysis of lung homogenate, and histopathology. Cell differential analysis of the BALF show that the numbers of neutrophils and lymphocytes increased significantly in the mice exposed to 40 microg nano-ceria at 1 d after instillation, and returned to control levels by 7 d. The lactate dehydrogenate activity in the BALF from the 40 microg group increased significantly during the whole experimental period. Pathological changes were only found in the lung tissues from the mice of 40 microg nano-ceria group. The changes were most obvious by 7 d post-exposure, and returned to normal by 28 d. No other changes were found. The results of the present study suggest that exposure to nano-ceria at the current levels in the ambient air may not cause respiratory toxicity.

Biotransformation is a critical factor that may modify the toxicity, behavior, and fate of engineered nanoparticles in the environment. CeO(2) nanoparticles (NPs) are generally recognized as stable under environmental and biological conditions. The present study aims to investigate the biotransformation of CeO(2) NPs in plant systems. Transmission electron microscopy (TEM) images show needlelike clusters on the epidermis and in the intercellular spaces of cucumber roots after a treatment with 2000 mg/L CeO(2) NPs for 21 days. By using a soft X-ray scanning transmission microscopy (STXM) technique, the needlelike clusters were verified to be CePO(4). Near edge X-ray absorption fine structure (XANES) spectra show that Ce presented in the roots as CeO(2) and CePO(4) while in the shoots as CeO(2) and cerium carboxylates. Simulated studies indicate that reducing substances (e.g., ascorbic acids) played a key role in the transformation process and organic acids (e.g., citric acids) can promote particle dissolution. We speculate that CeO(2) NPs were first absorbed on the root surfaces and partially dissolved with the assistance of the organic acids and reducing substances excreted by the roots. The released Ce(III) ions were precipitated on the root surfaces and in intercellular spaces with phosphate, or form complexes with carboxyl compounds during translocation to the shoots. To the best of our knowledge, this is the first report confirming the biotransformation and in-depth exploring the translocation process of CeO(2) NPs in plants.

With the increasing utilization of nanomaterials, there is a growing concern for the potential environmental and health effects of them. To assess the environmental risks of nanomaterials, better knowledge about their fate and toxicity in plants are required. In this work, we compared the phytotoxicity of nanoparticulate Yb(2)O(3), bulk Yb(2)O(3), and YbCl(3)·6H(2)O to cucumber plants. The distribution and biotransformation of the three materials in plant roots were investigated in situ by TEM, EDS, as well as synchrotron radiation based methods: STXM and NEXAFS. The decrease of biomass was evident at the lowest concentration (0.32 mg/L) when exposed to nano-Yb(2)O(3), while at the highest concentration, the most severe inhibition was from YbCl(3). The inhibition was dependent on the actual amount of toxic Yb uptake by the cucumber plants. In the intercellular regions of the roots, Yb(2)O(3) particles and YbCl(3) were all transformed to YbPO(4). We speculate that the dissolution of Yb(2)O(3) particles induced by the organic acids exuded from roots played an important role in the phytotoxicity. Only under the nano-Yb(2)O(3) treatment, YbPO(4) deposits were found in the cytoplasm of root cells, so the phytotoxicity might also be attributed to the Yb internalized into the cells.

The presence and release of nanoparticles (NPs) into the environment have important implications for human health and the environment. A critical aspect of the risk assessment of nanoparticles is to understand the interactions of manufactured nanoparticles with plants. In this study, the uptake and distribution characteristics of two types of ceria nanoparticles with sizes of ca. 7 nm and 25 nm in cucumber plants were investigated using a radiotracer method and other techniques. With increasing concentration of the nanoparticles, concentration dependent absorption by the plant roots was noticed, but the majority of the particles only loosely adhered to the root surface. The seedlings treated with 7 nm ceria particles showed significantly higher ceria contents in both roots and shoots than those exposed to 25 nm ceria particles at all test concentrations (2, 20, and 200 mg L(-1)). Only very limited amounts of ceria nanoparticles could be transferred from the roots to shoots because the entry of nanoparticles into the roots was difficult. However, the results of tissue distributions of ceria nanoparticles in the plants and two dimensional distributions of the particles in the leaves imply that once they have entered into the vascular cylinder, ceria nanoparticles could move smoothly to the end of the vascular bundle along with water flow. To the best of our knowledge, this is the first detailed study of uptake and distribution of metal oxide nanoparticles in plants.

Due to the unique physical and chemical properties, nanosized cerium oxide (n-CeO2) has attracted considerable interest in many fields of research. The potential, the growing use and the mass production of n-CeO2 have stimulated research on their potential impact on the environment and human health. However, the toxicological definition for CeO2 nanoparticles (NPs) is still quite controversial. In the present work, we evaluated the antibacterial activity of CeO2 NPs sized ca. 7 nm (7-CeO2), ca. 25 nm (25-CeO2) and their bulk counterpart (b-CeO2), using gram-negative Escherichia coli (E. coli). Our results suggest that all the three types of CeO2 particles have antibacterial activity, and both the NPs are more toxic than b-CeO2. The rise in intracellular ROS level induced by direct contact of particles with the surface of E. coli was involved in the mechanism for the antibacterial activity of CeO2 NPs. Exposure to 25-CeO2 could also impair the integrity of the outer membrane within E. coli cells. Due to agglomeration and negligible effect on membrane integrity, 7-CeO2 did not exhibit greater antibacterial activity than 25-CeO2.

The broad potential applications of manufactured nanomaterials call for urgent assessment of their environmental and biological safety. However, most of the previous work focused on the cell level performance; little was known about the consequences of nanomaterial exposure at the whole-body and organ levels. In the present paper, the radiotracer technique was employed to study the pulmonary deposition and the translocation to secondary target organs after ceria nanoparticles (nano-ceria) were intratracheally instilled into Wistar rats. It was found that 63.9 +/- 8.2% of the instilled nano-ceria remained in the lung by 28 d postexposure and the elimination half-life was 103 d. At the end of the test period, only 1/8-1/3 of the daily elimination of nano-ceria from the lung was cleared via the gastrointestinal tract, suggesting that phagocytosis by alveolar macrophages (AMs) with subsequent removal towards the larynx was no longer the predominant route for the elimination of nano-ceria from the lung. The whole-body redistribution of nano-ceria demonstrated that the deposited nano-ceria could penetrate through the alveolar wall into the systemic circulation and accumulate in the extrapulmonary organs. In vitro study suggested that nano-ceria would agglomerate and form sediments in the bronchoalveolar aqueous surrounding while binding to protein would be conducive to the redispersion of nano-ceria. The decrease in the size of agglomerates might enhance the penetration of nano-ceria into the systemic circulation. Our findings suggested that the effect of nanomaterial exposure, even at low concentration, should be assessed because of the potential lung and systemic cumulative toxicity of the nanomaterials.

Transferrin (Tf), an iron-transporting serum glycoprotein, which binds to receptors expressed at the surface of most proliferating cells with particularly high expression on erythroblasts and cancer cells, was chosen as the ligand to develop BCNU-loaded biodegradable poly(D,L-lactic acid) nanoparticles (NPs) containing a ligand, which specifically binds to glioma cells, and their anti-tumor ability was evaluated using a C6 glioma model. In vitro drug release behavior demonstrated that BCNU-loaded PLA NPs show certain sustained release characteristics. NPs with low molecular weight PLA showed a higher burst effect and a significantly faster drug release from PLA samples. The biodistribution of Tf-coated nanoparticles investigated by 99Tc-labeled SPECT showed that the surface-containing transferrin PLA nanoparticles were concentrated in the brain and no radioactive foci could be found outside the brain. Inhibition of tumor growth in the C6 tumor-bearing animal model showed that BCNU-loaded PLA NPs had stronger cytotoxicity and prolonged the average survival time of rats. Especially when treated at an early stage with a higher dosage of NPs, the average survival time of rats was prolonged 88.37%. Furthermore, one rat maintained normal behavior continuously for an observation period of up to 60 days.

As one of the most widely used nanomaterials, CeO2 nanoparticles (NPs) might be released into the aquatic environment. In this paper, the interaction of CeO2 NPs and Ce3+ ions (0~10 mg/L) with duckweed (Lemna minor L.) was investigated. CeO2 NPs significantly inhibited the root elongation of duckweed at concentrations higher than 0.1 mg/L, while the inhibition threshold of Ce3+ ions was 0.02 mg/L. At high doses, both reduced photosynthetic pigment contents led to cell death and induced stomatal deformation, but the toxicity of Ce3+ ions was greater than that of CeO2 NPs at the same concentration. According to the in situ distribution of Ce in plant tissues by μ-XRF, the intensity of Ce signal was in the order of root > old frond > new frond, suggesting that roots play a major role in the uptake of Ce. The result of XANES showed that 27.6% of Ce(IV) was reduced to Ce(III) in duckweed treated with CeO2 NPs. We speculated that the toxicity of CeO2 NPs to duckweed was mainly due to its high sensitivity to the released Ce3+ ions. To our knowledge, this is the first study on the toxicity of CeO2 NPs to an aquatic higher plant. [ABSTRACT FROM AUTHOR]

[Display omitted] • Three different deposition methods (hexanes, oleylamine, hydrazine) to deposit Co-P nanoparticle intermetallic compounds on the top of the TiO 2 nanotube surface. • The photocurrent saturated current density is improved by 1.15-fold using the oleylamine deposition method, compared with the deposition method with hexanes. • The overall photo-saturated photocurrent density is improved up to 1.7-fold of the TiO 2 NTs deposited with Co-P nanoparticles by Ar-ion sputtering. Sunlight is the cleanest and largest source of energy, even if the sunlight is somewhat unpredictable. Indeed, photoelectrochemical (PEC) water splitting affords a clean, carbon–neutral process, even if complex, to achieve the transform of photons in chemical energy (H 2). The true limitation of the process is related to the conversion in energy storage. In this work, we exploit Co-P nanoparticles and TiO 2 nanotubes, and additional modifications. Using organic species, including hexane, oleylamine, and hydrazine, control of the capping ligand of the TiO 2 nanotubes is achieved, allowing maximum order. Optimizing the deposition of Co-P nanoparticles, and by increasing the rate of water oxidation kinetics, the photocurrent saturated current density is improved by 1.15-fold. Additionally, a further modification at the surface of the TiO 2 NTs by Ar-ion sputtering is demonstrated to improve the overall photo-saturated photocurrent density up to 1.7-fold of the TiO 2 NTs deposited with Co-P nanoparticles. Finally, a further modification at the surface of the TiO 2 NTs by Ar-ion sputtering is demonstrated to improve the overall photo-saturated photocurrent density. [ABSTRACT FROM AUTHOR]

In the past decades, enzyme mimetics based on ceria nanoparticles (nanoceria) have been developed as potential substitutes for nature enzymes. The mixed valence states of cerium and the patterns of oxygen vacancies on crystal planes result in different enzyme mimetic activities. In this review we survey the bio-applications of nanoceria-based enzyme mimetics as well as the underlying mechanisms. Factors influencing the enzyme mimetic activities and future perspective of nanoceria-based enzyme mimetics are also addressed. [ABSTRACT FROM AUTHOR]

Cerium oxide nanoparticles (CeO NPs) have been considered as one type of emerging contaminants that pose great potential risks to the environment and human health. The effect of CeO NPs on plant-edible parts and health evaluation remains is necessary and urgently to be developed. In this study, we cultivated radish in Sigma CeO NP (<25 nm)-amended soils across a series of concentration treatments, i.e., 0 mg/kg as the control and 10, 50, and 100 mg/kg CeO NPs. The results showed that CeO NPs accelerated the fresh biomass accumulation of radish plant; especially in the treatment of 50 mg/kg CeO NPs, root expansion was increased by 2.2 times as much as the control. In addition, the relative chlorophyll content enhanced by 12.5, 12.9, and 12.2% was compared to control on 40 cultivation days. CeO NPs were mainly absorbed by the root and improved the activity of antioxidant enzyme system to scavenge the damage of free radicals in radish root and leaf. In addition, this study also indicated that the nanoparticles might enter the food chain through the soil into the edible part of the plant, which will be a potential threat to human health. [ABSTRACT FROM AUTHOR]

Investigating the geochemical behavior of CeO 2 nanoparticles (NPs) is important for understanding the environmental fate and risk of the exogenetic Ce in soil. However, systematic explorations of the interaction between critical soil components and CeO 2 NPs are lacking. In this report, a theoretical geochemical cycle of exogenetic CeO 2 NPs and CeCl 3 involving their response to soil organic matter (SOM) and Fe/Mn oxides were demonstrated by microcosm experiments. The Ce(IV) in CeO 2 NPs shows a slight reduction of (3.0–6.7%) after the treatment in humic acid. The reduction product was verified to be Ce(III)-oxalate. The transformation on chemical speciation stimulated the re-distribution of Ce in soil, with its main host phase changing from a residue state (94.68–96.50%) to an Fe/Mn oxide binding state (75.56–79.42%). Different from the SOM, Mn oxides (pyrolusite and nsutite) had an opposite redox effect on Ce compounds, greatly oxidizing the Ce(III) to Ce(IV) (95.2–100%). Simulated studies indicate that Mn oxide or ambient O 2 played a key role in the oxidation process. We speculate that disparate redox effects by soil components cause the speciation transformation and cyclic distribution and of Ce species in soil, potentially affecting the correlative mineral formation and metal bioavailability. [Display omitted] • The Ce(IV) in CeO 2 NPs shows a slight reduction in humic acid, which product was Ce(III)-oxalate. • Mn oxide or ambient O 2 played a key role in the oxidation process of Ce(III) to Ce(IV). • Different chemical speciation of Ce had different fractionation results in soil. • The geochemical cycle of CeO 2 NPs in soil is constructed for the first time. • The geochemical cycle mainly includes chemical transformation and distribution of Ce species. [ABSTRACT FROM AUTHOR]

Ceria nanoparticles (nanoceria) are well known as a superoxide scavenger. However, inherent superoxide-scavenging ability has only been found in the nanoceria with sizes of less than 5 nm and with very limited shape diversity. Reported herein is a strategy to significantly improve the superoxide-scavenging activity of nanoceria sized at greater than 5 nm. The nanoceria with sizes of greater than 5 nm, with different shapes, and with a negligible Ce3+/Ce4+ ratio can acquire remarkable superoxide-scavenging abilities through electron transfer. This method will make it possible to develop nanoceria-based superoxide-scavengers with long-acting activity and tailorable characteristics. [ABSTRACT FROM AUTHOR]

In order to assess the potential hazards of nanoparticles (NPs) releasing, better knowledge about their toxicity to microbes is required. However, it remains controversial whether NPs could exert particle-specific toxicity. In this study, the toxic impacts of four kinds of rare earth oxides (REO) NPs (La 2 O 3 , CeO 2 , Gd 2 O 3, and Yb 2 O 3 ) on gram-negative Escherichia coli ( E. coli ) pBR322 were examined. The results indicate that all the tested NPs possessed cytotoxicity against E. coli . To evaluate the ion-related toxicity of REO NPs, the NPs dissolution in the presence of test organisms was quantitatively measured using X-ray absorption fine structure (XAFS) spectroscopy. Our results suggest that NPs-cell contact could facilitate the dissolution of NPs, and the additional ionic release at the particle-cell interface might result in a substantial increase in the ion-related toxicities towards the test organisms. Therefore, the ion-related toxicity of NPs might be grossly underestimated if the additional dissolution of NPs caused by particle-cell contact was overlooked, further leading to a false interpretation of particle-specific toxicity. To the best of our knowledge, this is the first determination of the total NPs dissolution after particle-cell contact. These findings are helpful to advance mechanistic understanding of the toxicity exerted by dissolvable metal-based NPs. [ABSTRACT FROM AUTHOR]

The synthesis of mesoporous Prussian blue analogues through a template-free methodology and the application of these mesoporous materials as high-performance cathode materials in sodium-ion batteries is presented. Crystalline mesostructures were produced through a synergistically coupled nanocrystal formation and aggregation mechanism. As cathodes for sodium-ion batteries, the Prussian blue analogues all show a reversible capacity of 65 mA h g−1 at low current rate and show excellent cycle stability. The reported method stands as an environmentally friendly and low-cost alternative to hard or soft templating for the fabrication of mesoporous materials. [ABSTRACT FROM AUTHOR]