Graphene in the aquatic environment: adsorption, dispersion, toxicity and transformation

Enhanced degradation of few-layer black phosphorus by fulvic acid: Processes and mechanisms

The oxidation of the emerging nanomaterial black phosphorus (BP) affected by pH and oxygen has been carefully documented. However, in natural waters, there is a large amount of chemically reactive organic matters like fulvic acid (FA), whose impacts on degradation and stability of few-layer BP or BP nanosheets (BPNS) are scarcely disclosed. Hence, we investigated the kinetics of BPNS degradation products (H₂PO₂^-, HPO₃^2-, and PO₄^3-) in the presence of FA. The results showed that the apparent reaction rate constants of BPNS were 0.026, 0.050, and 0.060 d^-1 under oxygen-and-light condition and 0.005, 0.016, and 0.023 d^-1 under hypoxia-and-darkness condition at FA gradients of 0, 2.5, and 5 mgC/L, respectively. Microscopic observations, simple molecular simulation experiment, and density functional theory computation explained that FA significantly enhanced the degradation of P atoms on the BPNS surface through the indirect pathway of reducing the energy barrier of O₂ dissociative adsorption and the direct pathway of chemical adsorption, which caused the P-P bond on the BPNS surface to break down and formed P-O bonds or C-P bonds. This study revealed for the first time the degradation mechanism of BPNS in the presence of FA, which is a chemical mechanism of the BPNS transformation behavior. It helps to make a more scientific risk assessment of BP in natural waters.

Tailored Sky-Parking Architectures of 3D Graphene Oxide Towards Highly-Efficient Water Purification

The widespread use of chemicals has brought serious water pollution threatening human health and environment, which requires green, fast, and low-cost purification urgently. Here, we build up a novel material family of sky-parking-like 3D structured graphene oxides (SP-GOs) with adjustable interlayer-space of 0.8-1.7 nm via the insertion of different sized diamine compounds as support pillars between GO layers. The assembled 3D SP-GOs exhibit superior adsorption capacity and short removal time for various aromatic organic compounds in water, achieving record-breaking maximum adsorption capacity of 535.79 mg g^-1 toward the most common water-pollutant bisphenol A (BPA) at ambient conditions as well as significantly improved removal of other organic pollutants including sulfapyridine, carbamazepine, ketoprofen and 2-naphthol. The construction of SP-GO provides a simple approach for evolving the GO material from 2D to 3D and a new avenue for the decontamination of pollutants in environmental remediation.

MXenes Antibacterial Properties and Applications: A Review and Perspective

The mutations of bacteria due to the excessive use of antibiotics, and generation of antibiotic-resistant bacteria have made the development of new antibacterial compounds a necessity. MXenes have emerged as biocompatible transition metal carbide structures with extensive biomedical applications. This is related to the MXenes' unique combination of properties, including multifarious elemental compositions, 2D-layered structure, large surface area, abundant surface terminations, and excellent photothermal and photoelectronic properties. The focus of this review is the antibacterial application of MXenes, which has attracted the attention of researchers since 2016. A quick overview of the synthesis strategies of MXenes is provided and then summarizes the effect of various factors (including structural properties, optical properties, surface charges, flake size, and dispersibility) on the biocidal activity of MXenes. The main mechanisms for deactivating bacteria by MXenes are discussed in detail including rupturing of the bacterial membrane by sharp edges of MXenes nanoflakes, generating the reactive oxygen species (ROS), and photothermal deactivating of bacteria. Hybridization of MXenes with other organic and inorganic materials can result in materials with improved biocidal activities for different applications such as wound dressings and water purification. Finally, the challenges and perspectives of MXene nanomaterials as biocidal agents are presented.

Toxicological effects resulting from co-exposure to nanomaterials and to a β-blocker pharmaceutical drug in the non-target macrophyte species Lemna minor

The wide use of carbon-based materials for various purposes leads to their discharge in the aquatic systems, and simultaneous occurrence with other environmental contaminants, such as pharmaceutical drugs. This co-occurrence can adversely affect exposed aquatic organisms. Up to now, few studies have considered the simultaneous toxicity of nanomaterials, and organic contaminants, including pharmaceutical drugs, towards aquatic plants. Thus, this study aimed to assess the toxic effects of the co-exposure of propranolol (PRO), and nanomaterials based on cellulose nanocrystal, and graphene oxide in the aquatic macrophyte Lemna minor. The observed effects included reduction of growth rate in 13% in co-exposure 1 (nanomaterials + PRO 5 μg L^-1), and 52-64% in co-exposure 2 (nanomaterials + PRO 51.3 mg L^-1), fresh weight reduction of 94-97% in co-exposure 2 compared to control group, and increased pigment production caused by co-exposure treatments. The analysis of PCA showed that co-exposure 1 (nanomaterials + PRO 5 μg L^-1) positively affected growth, and fresh weight, and co-exposure 2 positively affected pigments content. The results suggested that the presence of nanomaterials enhanced the overall toxicity of PRO, exerting deleterious effects in the freshwater plant L. minor, suggesting that this higher toxicity resulting from co-exposure was a consequence of the interaction between nanomaterials and PRO.

Adsorption Studies at the Graphene Oxide-Liquid Interface: A Molecular Dynamics Study

The adsorption of organic aromatic molecules, namely aniline, onto graphene oxide is investigated using molecular simulations. The effect of the oxidation level of the graphene oxide sheet as well as the presence of two different halide salts, sodium chloride and sodium iodide, were examined. The aniline molecule in the more-reduced graphene oxide case, in the absence of added salt, showed a slightly greater affinity for the graphene oxide-water interface as compared to the oxidized form. The presence of the iodide ion increased the affinity of the aniline molecule in the reduced case but had the opposite effect for the more-oxidized form. The effect of oxidation and added salt on the interfacial water layer was also examined.

An Insight into the Combined Toxicity of 3,4-Dichloroaniline with Two-Dimensional Nanomaterials: From Classical Mixture Theory to Structure-Activity Relationship

The assessment and prediction of the toxicity of engineered nanomaterials (NMs) present in mixtures is a challenging research issue. Herein, the toxicity of three advanced two-dimensional nanomaterials (TDNMs), in combination with an organic chemical (3,4-dichloroaniline, DCA) to two freshwater microalgae (Scenedesmus obliquus and Chlorella pyrenoidosa), was assessed and predicted not only from classical mixture theory but also from structure-activity relationships. The TDNMs included two layered double hydroxides (Mg-Al-LDH and Zn-Al-LDH) and a graphene nanoplatelet (GNP). The toxicity of DCA varied with the type and concentration of TDNMs, as well as the species. The combination of DCA and TDNMs exhibited additive, antagonistic, and synergistic effects. There is a linear relationship between the different levels (10, 50, and 90%) of effect concentrations and a Freundlich adsorption coefficient (K_F) calculated by isotherm models and adsorption energy (E_a) obtained in molecular simulations, respectively. The prediction model incorporating both parameters K_F and E_a had a higher predictive power for the combined toxicity than the classical mixture model. Our findings provide new insights for the development of strategies aimed at evaluating the ecotoxicological risk of NMs towards combined pollution situations.

Integrating FTIR 2D correlation analyses, regular and omics analyses studies on the interaction and algal toxicity mechanisms between graphene oxide and cadmium

Graphene oxide (GO, a popular 2D graphene-based nanomaterial) has developed quickly and has received considerable attention for its applications in environmental protection and pollutant removal. However, significant knowledge gaps still exist about the interaction characteristic and joint toxicity mechanism of GO and cadmium (Cd) on aquatic organisms. In this study, GO showed a high adsorption capacity (120. 6 mg/g) and strong adsorption affinity (K_L = 0.85 L/mg) for Cd²⁺. Integrating multiple analytical methods (e.g., electron microscopy, Raman spectra, and 2D correlation spectroscopy) revealed that Cd²⁺ is uniformly adsorbed on the GO surface and edge mainly through cation-π interactions. The combined ecological effects of GO and Cd²⁺ on Chlorella vulgaris were observed. Cd²⁺ induced more severe growth inhibition, photosynthesis toxicity, ultrastructure damage and plasmolysis than GO. Interestingly, we found that GO nanosheets could augment the algal toxicity of Cd²⁺ (e.g., chlorophyll b, mitochondrial membrane damage, and uptake). Transcriptomics and metabolomics further explained the underlying mechanism. The results indicated that the regulation of PSI-, PSII-, and metal transport-related genes (e.g., ABCG37 and ZIP4) and the inhibition of metabolic pathways (e.g., amino acid, fatty acid, and carbohydrate metabolism) were responsible for the persistent phytotoxicity. The present work provides mechanistic insights into the roles of coexisting inorganic pollutants on the environmental fate and risk of GO in aquatic ecosystems.

Insight into the interaction between trimethoprim and soluble microbial products produced from biological wastewater treatment processes

Soluble microbial products (SMPs), dissolved organic matter excreted by activated sludge, can interact with antibiotics in wastewater and natural water bodies. Interactions between SMPs and antibiotics can influence antibiotic migration, transformation, and toxicity but the mechanisms involved in such interactions are not fully understood. In this study, integrated spectroscopy approaches were used to investigate the mechanisms involved in interactions between SMPs and a representative antibiotic, trimethoprim (TMP), which has a low biodegradation rate and has been detected in wastewater. The results of liquid chromatography-organic carbon detection-organic nitrogen detection indicated that the SMPs used in the study contained 15% biopolymers and 28% humic-like substances (based on the total dissolved organic carbon concentration) so would have contained sites that could interact with TMP. A linear relationship of fluorescent intensities of tryptophan protein-like substances in SMP was observed (R²>0.99), indicating that the fluorescence enhancement between SMP and TMP occurred. Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy indicated that carboxyl, carbonyl, and hydroxyl groups were the main functional groups involved in the interactions. The electrostatic and π-π interactions were discovered by the UV-vis spectra and ¹H nuclear magnetic resonance spectra. Structural representations of the interactions between representative SMP subcomponents and TMP were calculated using density functional theory, and the results confirmed the conclusions drawn from the ¹H nuclear magnetic resonance spectra. The results help characterize SMP-TMP complexes and will help understand antibiotic transformations in wastewater treatment plants and aquatic environments.

Atomistic insights into migration mechanism of graphene-based membranes on soil mineral phases

Graphene-based membranes (GBM) will migrate in the soil and enter the groundwater system or plant roots, which will eventually pose potential risks to human beings. The migration mechanism of GBM depends on the interface behavior of complex soil components. Herein, we use molecular dynamics (MD) simulations to probe the interface behavior between GBM and three type minerals (quartz, calcite and kaolinite). Based on the investigation of binding energy, maximum pulling force and barrier energy, the order of the difficulty of GBM adsorption and desorption on the three minerals from small to large is roughly: quartz, calcite and kaolinite respectively. The graphene-oxide (GO), improves the binding energy and energy barrier, making GBM difficult to migrate in soil. Remarkably, a larger GBM sheet and high velocity external load improve GBM migration in soil to a certain extent. These investigations give the dynamic information on the GBM/mineral interaction and provide nanoscale insights into the migration mechanisms of GBM in soil.

The interaction mechanisms of co-existing polybrominated diphenyl ethers and engineered nanoparticles in environmental waters: A critical review

This review focuses on the occurrence and interactions of engineered nanoparticles (ENPs) and brominated flame retardants (BFRs) such as polybrominated diphenyl ethers (PBDEs) in water systems and the generation of highly complex compounds in the environment. The release of ENPs and BFRs (e.g. PBDEs) to aquatic environments during their usage and disposal are summarised together with their key interaction mechanisms. The major interaction mechanisms including electrostatic, van der Waals, hydrophobic, molecular bridging and steric, hydrogen and π-bonding, cation bridging and ligand exchange were identified. The presence of ENPs could influence the fate and behaviour of PBDEs through the interactions as well as induced reactions under certain conditions which increases the formation of complex compounds. The interaction leads to alteration of behaviour for PBDEs and their toxic effects to ecological receptors. The intermingled compound (ENPs-BFRs) would show different behaviour from the parental ENPs or BFRs, which are currently lack of investigation. This review provided insights on the interactions of ENPs and BFRs in artificial, environmental water systems and wastewater treatment plants (WWTPs), which are important for a comprehensive risk assessment.

Use of nanoparticle-coated bacteria for the bioremediation of organic pollution: A mini review

Nanoparticle (NP)-coated (immobilized) bacteria are an effective method for treating environmental pollution due to their multifarious benefits. This review collates a vast amount of existing literature on organic pollution treatment using NP-coated bacteria. We discuss the features of bacteria, NPs, and decoration techniques of NP-bacteria assemblies, with special attention given to the surface modification of NPs and connection mechanisms between NPs and cells. Furthermore, the performance of NP-coated bacteria was examined. We summarize the factors that affect bioremediation efficiency using coated bacteria, including pH, temperature, and agitation, and the possible mechanisms involving them are proposed. From future perspectives, suitable surface modification of NPs and wide application in real practice will make the NP-coated bacterial technology a viable treatment strategy.

Preparation of MnO2-Carbon Materials and Their Applications in Photocatalytic Water Treatment

Water pollution is one of the most important problems in the field of environmental protection in the whole world, and organic pollution is a critical one for wastewater pollution problems. How to solve the problem effectively has triggered a common concern in the area of environmental protection nowadays. Around this problem, scientists have carried out a lot of research; due to the advantages of high efficiency, a lack of secondary pollution, and low cost, photocatalytic technology has attracted more and more attention. In the past, MnO₂ was seldom used in the field of water pollution treatment due to its easy agglomeration and low catalytic activity at low temperatures. With the development of carbon materials, it was found that the composite of carbon materials and MnO₂ could overcome the above defects, and the composite had good photocatalytic performance, and the research on the photocatalytic performance of MnO₂-carbon materials has gradually become a research hotspot in recent years. This review covers recent progress on MnO₂-carbon materials for photocatalytic water treatment. We focus on the preparation methods of MnO₂ and different kinds of carbon material composites and the application of composite materials in the removal of phenolic compounds, antibiotics, organic dyes, and heavy metal ions in water. Finally, we present our perspective on the challenges and future research directions of MnO₂-carbon materials in the field of environmental applications.

Antimicrobial activities of graphene oxide against biofilm and intracellular Staphylococcus aureus isolated from bovine mastitis

BACKGROUND

S. aureus is one of the causative agents of bovine mastitis. The treatment using conventional antimicrobials has been hampered due to the development of antimicrobial resistance and the ability of the bacteria to form biofilms and localize inside the host cells.

OBJECTIVES

Here, the efficacy of graphene oxide (GO), a carbon-based nanomaterial, was tested against the biofilms and intracellular S. aureus invitro. Following that, the mechanism for the intracellular antimicrobial activities and GO toxicities was elucidated.

METHODS

GO antibiofilm properties were evaluated based on the disruption of biofilm structure, and the intracellular antimicrobial activities were determined by the survival of S. aureus in infected bovine mammary cells following GO exposure. The mechanism for GO intracellular antimicrobial activities was investigated using endocytosis inhibitors. GO toxicity towards the host cells was assessed using a resazurin assay.

RESULTS

At 100 ug/mL, GO reduced between 30 and 70% of S. aureus biofilm mass, suggesting GO's ability to disrupt the biofilm structure. At 200 ug/mL, GO killed almost 80% of intracellular S. aureus, and the antimicrobial activities were inhibited when cells were pre-treated with cytochalasin D, suggesting GO intracellular antimicrobial activities were dependent on the actin-polymerization of the cell membrane. At < 250 ug/mL, GO enhanced the viability of the Mac-T cell, and cells were only affected at higher dosages.

CONCLUSION

The in vitro efficacy of GO against S. aureus in vitro suggested the compound could be further tested in Vivo to zrecognize its potential as one of the components of bovine mastitis therapy.

Trends and prospects in graphene and its derivatives toxicity research: A bibliometric analysis

The purpose of this paper is to explore the current research status, hot topics, and future prospects in the field of graphene and its derivatives toxicity. In the article, the Web of Science Core Collection database was used as the data source, and the CiteSpace and VOSviewer were used to conduct a visual analysis of the last 10 years of research on graphene and its derivatives toxicity. A total of 8573 articles were included, and we analyzed the literature characteristics of the research results in the field of graphene and its derivatives toxicity, as well as the distribution of authors and co-cited authors; the distribution of countries and institutions; the situation of co-cited references; and the distribution of journals and categories. The most prolific countries, institutions, journals, and authors are China, the Chinese Academy of Sciences, RSC Advances, and Wang, Dayong, respectively. The co-cited author with the most citations was Akhavan, Omid. The five research hotspot keywords in the field of graphene and its derivatives toxicity were "nanomaterials," "exposure," "biocompatibility," "adsorption," and "detection." Frontier topics were "facile synthesis," "antibacterial activity," and "carbon dots." Our study provides perspectives for the study of graphene and its derivatives toxicity and yields valuable information and suggestions for the development of graphene and its derivatives toxicity research in the future.

Role of heteroaggregation and internalization in the toxicity of differently sized and charged plastic nanoparticles to freshwater microalgae

The toxic effect of waterborne nanoplastics is a manifestation of bio-nano interfacial interactions. Although nanoplastics with different physicochemical characteristics are known to exhibit distinct toxicities, it remains poorly understood how the properties of nanoplastics affect the bio-nano interface interactions. Here, polystyrene nanoparticles (PSNPs) varying in size (50, 300, and 500 nm) and surface charge (negative and positive charge) were employed to explore the interplay between PSNPs and algal cells (Chlamydomonas reinhardtii), with special focus on the heteroaggregation of PSNPs and microalgae, PSNPs cellular internalization, and cellular physiological responses. Results showed that large-sized PSNPs (300 and 500 nm) caused apparent toxicity to C. reinhardtii, mainly due to light blockage resulting from the PSNPs-microalgae heteroaggregation and the shading effect of PSNPs, which was independent of PSNPs concentrations. However, the toxicity of small-sized PSNPs (50 nm) was controlled by both particle surface charge and particle concentration. The positively charged PS-NH₂ was more readily heteroaggregated with microalgae than the negatively charged PS-COOH, leading to photosynthesis damage-induced toxicity. Increasing the concentration of small-sized PSNPs stimulated the secretion of extracellular polymeric substances, allowing more PSNPs to attach on the cell surface and further to enter the cell, which was responsible for the increased toxicity. These findings provide new insights into how nanoplastics induce contact toxicity in microalgae cells through specific biointerfacial interactions.

Reduced graphene oxide accelerates the dissipation of 14C-Triclosan in paddy soil via adsorption interactions

Reduced graphene oxide (RGO) is one of common carbon nanomaterials, which is widely used in various fields. Triclosan is an antimicrobial agent added in pharmaceuticals and personal care products. Extensive release of RGO and triclosan has posed potential risks to humans and the environment. The impact of RGO on the fate of triclosan in paddy soil is poorly known. ¹⁴C-Triclosan was employed in the present study to determine its distribution, degradation and mineralization in paddy soil mixed with RGO. Compared with the control, RGO (500 mg kg^-1) significantly inhibited the mineralization of ¹⁴C-triclosan, and reduced its extractability by 6.5%. The bound residues of triclosan in RGO-contaminated soil (100 and 500 mg kg^-1) were 2.9-13.3% greater than that of the control at 112 d. RGO also accelerated the dissipation of triclosan, and its degradation products in both treatments and controls were tentatively identified via ¹⁴C-labeling method and LC-Q-TOF-MS analysis. The concentrations of the major metabolites (methyl-triclosan and dechlorinated dimer) were inversely related with the concentrations of RGO. RGO at 50 mg kg^-1 or lower had a negligible effect on the degradation of triclosan in paddy soil. Triclosan was strongly adsorbed onto RGO-contaminated soil, which may play a vital role in the fate of triclosan in RGO-contaminated paddy soil. Interestingly, RGO had little effect on triclosan-degrading bacteria via soil microbial community analysis. This study helps understand the effects of RGO on the transformation of triclosan in paddy soil, which is of significance to evaluate the environmental risk of triclosan in RGO-contaminated soil.

Insights into the mechanism underlying remediation of Cr(VI) contaminated aquifer using nanoscale zero-valent iron@reduced graphene oxide

Currently, there is an urgent need to develop functional nanomaterials for highly effective environmental remediation. However, the long-term effect of remedial materials upon their injection into contaminated aquifer has frequently been overlooked. Here, the remediation of Cr(VI) contaminated aquifer by reduced graphene oxide (rGO) supported nanoscale zero-valent iron (nZVI@rGO) was investigated from a long-term perspective. The performances of nZVI@rGO samples with different rGO loadings in the removal of aqueous Cr(VI) were evaluated in batch experiments. The electron transfer properties different nZVI@rGO samples were investigated by measuring their corrosive potentials using the steady-state Tafel polarization curves. The results show that the electron transfer efficiency between Cr(VI) and nZVI@rGO is enhanced owing to the large reactive conjugated structure of rGO. Besides, the surface passivation of nZVI is effectively retarded due to the uniform accommodation of Cr(III) precipitates on rGO. The structure and composition of nZVI@rGO before and after Cr(VI) removal were analyzed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The characterization results revealed that most Cr(VI) ions (∼90%) will be reduced to Cr(III) precipitates on nZVI@rGO as the passivation product. Accordingly, Cr(VI) ions tend to react more readily at less blocked regions on the surface of rGO, and a layer-by-layer passivation model on nZVI@rGO surface is proposed. Our results provide new insights into the mechanism underlying the long-term remediation of Cr(VI) contaminated aquifer using nZVI@rGO, which helps design new materials and approaches for practical in-situ remediation engineering.

Synthetic Nanoarchitectonics of Functional Organic-Inorganic 2D Germanane Heterostructures via Click Chemistry

Succeeding graphene, 2D inorganic materials made of reactive van der Waals layers, like 2D germanane (2D-Ge) derivatives, have attracted great attention because their physicochemical characteristics can be entirely tuned by modulating the nature of the surface substituent. Although very interesting from a scientific point of view, almost all the reported works involving 2D-Ge derivatives are focused on computational studies. Herein, a first prototype of organic-inorganic 2D-Ge heterostructure has been synthesized by covalently anchoring thiol-rich carbon dots (CD-SH) onto 2D allyl germanane (2D-aGe) via a simple and green "one-pot" click chemistry approach. Remarkably, the implanted characteristics of the carbon nanomaterial provide new physicochemical features to the resulting 0D/2D heterostructure, making possible its implementation in yet unexplored optoelectronic tasks-e.g., as a fluorescence resonance energy transfer (FRET) sensing system triggered by supramolecular π-π interactions-that are inaccessible for the pristine 2D-aGe counterpart. Consequently, this work builds a foundation toward the robust achievement of functional organic-inorganic 2D-Ge nanoarchitectonics through covalently assembling thiol-rich carbon nanoallotropes on commercially available 2D-aGe.

Relationship between graphene and pedosphere: A scientometric analysis

The mass production and application of graphene have gradually expanded from academic research to industrial applications, which will inevitably lead to graphene entering the soil actively and passively. Therefore, the relationship between graphene and the pedosphere has attracted a lot of attention in the last decade. The most important question is whether graphene will harm soil health. Fortunately, the evidence is that graphene can alter soil physicochemical properties and microbial communities to some extent, but not dramatically. On this basis, the role of graphene in soil has been investigated in all directions. This review summarizes the literature on the relationship between graphene and soils. Topics include remediation and sensing of soil using graphene materials, the effects of graphene on soil, and the effects of graphene in soil on plant growth. At the same time, this review also uses bibliometrics to review the history of the topic. The number of papers published each year, participating countries, participating institutions and important articles were analyzed in detail. Finally, based on the published literature, we described the future perspectives of graphene and the pedosphere.

Self-polishing antifouling coatings based on benzamide derivatives containing capsaicin

In this study, N-hydroxymethylbenzamide was alkylated with various aromatic compounds to obtain five novel benzamide derivatives containing capsaicin (BDCC), and the BDCC were incorporated into coatings as auxiliary agents. The relationships between properties and structures were discussed based on experimental and theoretical results. The theoretical results showed the optimized configurations of BDCC and confirmed that the benzene ring, phenolic hydroxyl, ester and amide groups were active sites. Experimental results indicated that the antimicrobial and antifouling effects of compounds b1, b2 and b3 were better than those of chlorothalonil, their MIC and MBC values were no more than 64 and 512 μg·mL-1, and their test panels were covered only with small amounts of dirt and biofilms; they worked well as green antifouling additives. The experimental and theoretical results showed that BDCC and BDCC antifouling coatings were effective and eco-friendly.

Uptake Route Altered the Bioavailability of Graphene in Misgurnus anguillicaudatus: Comparing Waterborne and Sediment Exposures

Numerous studies on the bioavailability of graphene-based nanomaterials relate to the water-only exposure route. However, the sediment exposure route should be the most important pathway for benthic organisms to ingest graphene, while to date little work on the bioavailability of graphene in benthic organisms has been explored. In this study, with the help of carbon-14-labeled few-layer graphene (¹⁴C-FLG), we quantificationally compared the bioaccumulation, biodistribution, and elimination kinetics of ¹⁴C-FLG in loaches via waterborne and sediment exposures. After 72 h of exposure, the accumulated ¹⁴C-FLG in loaches exposed via waterborne was 14.28 μg/g (dry mass), which was 3.18 times higher than that (4.49 μg/g) exposed via sediment. The biodistribution results showed that, compared to waterborne exposure, sediment exposure remarkably facilitated the transport of ¹⁴C-FLG from the gut into the liver, which made it difficult to be excreted. Although ¹⁴C-FLG did not cause significant hepatotoxicity, the disruption of intestinal microbiota homeostasis, immune response, and several key metabolic pathways in the gut were observed, which may be due to the majority of ¹⁴C-FLG being accumulated in the gut. Overall, this study reveals the different bioavailabilities of graphene in loaches via waterborne and sediment exposures, which is helpful in predicting its bioaccumulation capability and trophic transfer ability.

Understanding interactions between biomolecules and two-dimensional nanomaterials using in silico microscopes

Two-dimensional (2D) nanomaterials such as graphene are increasingly used in research and industry for various biomedical applications. Extensive experimental and theoretical studies have revealed that 2D nanomaterials are promising drug delivery vehicles, yet certain materials exhibit toxicity under biological conditions. So far, it is known that 2D nanomaterials possess strong adsorption propensities for biomolecules. To mitigate potential toxicity and retain favorable physical and chemical properties of 2D nanomaterials, it is necessary to explore the underlying mechanisms of interactions between biomolecules and nanomaterials for the subsequent design of biocompatible 2D nanomaterials for nanomedicine. The purpose of this review is to integrate experimental findings with theoretical observations and facilitate the study of 2D nanomaterial interaction with biomolecules at the molecular level. We discuss the current understanding and progress of 2D nanomaterial interaction with proteins, lipid membranes, and DNA based on molecular dynamics (MD) simulation. In this review, we focus on the 2D graphene nanosheet and briefly discuss other 2D nanomaterials. With the ever-growing computing power, we can image nanoscale processes using MD simulation that are otherwise not observable in experiment. We expect that molecular characterization of the complex behavior between 2D nanomaterials and biomolecules will help fulfill the goal of designing effective 2D nanomaterials as drug delivery platforms.

Retention of graphene oxide and reduced graphene oxide in porous media: Diffusion-attachment, interception-attachment and straining

The aggregation, deposition and retention of graphene oxide (GO) and reduced graphene oxide (RGO) were investigated systematically to estimate their mobility in the environment. RGO aggregates faster than GO, resulting in weaker diffusive transfer and a lower deposition rate on oxide surfaces. In NaCl, the critical deposition concentration of RGO (CDC_RGO) is smaller than CDC_GO on the SiO₂ surface, indicating that RGO achieves favorable deposition at lower ionic strength. In CaCl₂, Ca²⁺ bridging causes close CDC_GO and CDC_RGO. The retention process was observed in the photolithographic SiO₂ and Al₂O₃ micromodels. GO and RGO particles approach collectors mainly via interception before attachment. The interactive forces have a limited effect on the particle retention. The larger RGO aggregates cause greater extent interception and straining, resulting in lower mobility than GO in porous media. The mobility of GO and RGO show different trends in quartz crystal microbalance with dissipation (QCM-D) and in micromodels because the interception and straining mechanisms exist in pore space. Micromodel observation confirms the processes of interception and straining. The combination of QCM-D and micromodel experiments provides the connection of diffusion-attachment, interception-attachment and straining, which comprehensively explains the higher mobility of GO than RGO in porous media.

Impacts of photoaging on the interactions between graphene oxide and proteins: Mechanisms and biological effect

Graphene oxide (GO) are subjected to photoaging in aquatic environment, and inevitably enter biota and then interact with proteins. Here, the interactions of pristine and photoaged GO with two typical proteins (bovine serum albumin (BSA) and lysozyme) were systematically investigated. Due to long term photoirradiation (1-3 day), the lateral size of GO decreased greatly, and the oxygen-containing groups decreased as well while the graphitic carbon contents increased. Compared to pristine GO, the photoaged GO displayed stronger binding affinities with both proteins, which was mainly attributed to the increased binding sites as a result of smaller lateral size and increased hydrophobicity. The photoaging effect was more obvious for the negatively charged BSA, because hydrogen bonding and van der Waals force were mainly involved in the enthalpy-driven interactions between them. While, the strong electrostatic attraction between the positively charged lysozyme and GO diminished the photoaging effect. Analyses of synchronous, three-dimensional fluorescence spectra and fibrillation experiments intensified that the photoaged GO induced more serious changes in conformational structure of BSA and exhibited stronger inhibition on fibrillation of BSA compared to pristine GO. This study provided novel insights into the increased ecological risks of GO as a result of photoaging.

Impact of secondary salts, temperature, and pH on the colloidal stability of graphene oxide in water

The stability of graphene oxide (GO) in water is extremely relevant because of its application as an adsorbent material, as well as for its fate and behavior in the environment. Zeta potential was used to study the effect of secondary salts (carbonate, sulfate, and phosphate), temperature (20 to 60 °C), and pH (5 to 9) on the stability of six different GOs produced from natural, synthetic, and amorphous graphite-with and without the use of attrition milling. Generally, GOs produced with attrition-milled graphites had lower ζ-potentials than their unmilled counterparts because of their smaller particle sizes and higher concentration of oxygen-containing functional groups. It was observed that GO produced from graphite and synthetic graphite had ζ-potential values lower than -30 mV, even at 30 °C. However, it was observed that all the GOs studied were unstable in the presence of carbonate and sulfate salts at concentrations between 170 and 1695 mg L^-1, as they reached a ζ-potential of -4.1 mV. Density-functional theory electronic structure calculations suggested that the instability of GO in the presence of carbonate and sulfate was caused by the abstraction of a proton resulting in interaction energies E _int of 28.3 and 168.9 kJ mol^-1, respectively. Our results suggest that temperatures above 30 °C, as well as carbonate and sulfate salts at concentrations relevant to arid and semi-arid regions, could promote the formation of agglomerates of GO, thus limiting its use and mobility in water.

Toxicological effects of three different types of highly pure graphene oxide in the midge Chironomus riparius

Graphene oxide (GO) is a carbon nanomaterial used in electronics, biomedicine, environmental remediation and biotechnology. The production of graphene will increase in the upcoming years. The carbon nanoparticles (NPs) are released into the environment and accumulated in aquatic ecosystems. Information on the effects of GO in aquatic environments and its impact on organisms is still lacking. The aim of this study was to synthesise and characterise label-free GO with controlled lateral dimensions and thickness - small GO (sGO), large GO (lGO) and monolayer GO (mlGO) - and determine their impact on Chironomus riparius, a sentinel species in the freshwater ecosystem. Superoxide dismutase (SOD) and lipid peroxidation (LPO) was evaluated after exposures for 24 h and 96 h to 50, 500, and 3000 μg/L. GOs accumulated in the gut of C. riparius and disturbed its antioxidant metabolism. We suggest that all types of GO exposure can upregulate of SOD. Moreover, both lGO and mlGO treatments caused LPO damage in C. riparius in comparison to sGO, proving its favourable lateral size impact in this organism. Our results indicate that GOs could accumulate and induce significant oxidative stress on C. riparius. This work shows new information about the potential oxidative stress of these NMs in aquatic organisms.

Remediation of noxious wastewater using nanohybrid adsorbent for preventing water pollution

Removal of toxic elements from wastewater effluent has got a lot of attention because of their severe negative effects on human and environmental health. In the past few years, rapid urbanization and industrial activities in developing countries have exacerbated the destruction of the environment. Most of the wastewater effluents are discharged untreated or inadequately treated, which has become a major concern due to its impact on sustainability and the environment. This is imperative to implement, innovative and resourceful wastewater treatment technologies requiring low investment. Among the various treatment technologies, cutting-edge processes in nano-material sciences have recently piqued the interest of scientists. Nanohybrid absorbents have the potential in improving wastewater treatment and increase water supply by utilizing unconventional water resources. Carbon nanotubes, titanium oxide, manganese oxide, activated carbon (AC), magnesium oxide, graphene, ferric oxides, and zinc oxide are examples of nano-adsorbents that are used to eliminate pollutants. This also demonstrated the effective removal of contaminants along with the harmful effects of chemicals, colorants, and metals found in wastewater. The present manuscript examines potential advances in nanotechnology in wastewater treatment for the prevention of water and soil pollution. This systematic review aims to highlight the importance of nanohybrid absorbents treatment technology for wastewater treatment and to explain how nanohybrid absorbents have the potential to revolutionize industrial pollution. There are also other published review articles on this topic but the present review covers an in-depth information on nano-adsorbents and their targeted contaminants.

Graphene Oxide and Biomolecules for the Production of Functional 3D Graphene-Based Materials

Graphene and its derivatives have been widely employed in the manufacturing of novel composite nanomaterials which find applications across the fields of physics, chemistry, engineering and medicine. There are many techniques and strategies employed for the production, functionalization, and assembly of graphene with other organic and inorganic components. These are characterized by advantages and disadvantages related to the nature of the specific components involved. Among many, biomolecules and biopolymers have been extensively studied and employed during the last decade as building blocks, leading to the realization of graphene-based biomaterials owning unique properties and functionalities. In particular, biomolecules like nucleic acids, proteins and enzymes, as well as viruses, are of particular interest due to their natural ability to self-assemble via non-covalent interactions forming extremely complex and dynamic functional structures. The capability of proteins and nucleic acids to bind specific targets with very high selectivity or the ability of enzymes to catalyse specific reactions, make these biomolecules the perfect candidates to be combined with graphenes, and in particular graphene oxide, to create novel 3D nanostructured functional biomaterials. Furthermore, besides the ease of interaction between graphene oxide and biomolecules, the latter can be produced in bulk, favouring the scalability of the resulting nanostructured composite materials. Moreover, due to the presence of biological components, graphene oxide-based biomaterials are more environmentally friendly and can be manufactured more sustainably compared to other graphene-based materials assembled with synthetic and inorganic components. This review aims to provide an overview of the state of the art of 3D graphene-based materials assembled using graphene oxide and biomolecules, for the fabrication of novel functional and scalable materials and devices.

Fabrication of environmentally-friendly composited sponges for efficient removal of fluoroquinolones antibiotics from water

In this study, two environmentally-friendly macroscopically formal (PVF) composited sponges (PL and PLS) functionalized with lignin and lignosulfonate, respectively, were fabricated by a one-step mechanical foaming method. PLS, obtained with the fed mass ratio of 0.3:1 lignosulfonate to PVF in the preparation process, possessed a large specific surface area of approximately 22.396 m²/g, a three-dimensional skeleton structure with a skeletal density of 3.236 g/cm³, and 0.338 mmol/g of acidic oxygen-containing groups. Thus, it showed a high adsorption capacity of 0.16-0.24 mmol/g in removing seven antibiotics, of the popular fluoroquinolones (FQs) family from water. The contributions of hydrogen bonding, electrostatic attraction (EA) and π-π electron donor-acceptor interaction to the adsorption of FQs onto the PL and PLS sponges were analyzed systematically by investigating the pH dependence of the adsorption capacity, and the changes in adsorption of two sub structural analogs of FQs as molecular probes, and by performing theoretical calculations. The EA between the acidic oxygen-containing groups on the sponges and the amino groups of FQs played a dominant role in adsorption in near neutral conditions, leading to a superior adsorption performance for PLS. Overall, the composited sponges have the advantages of simple production, environmental-friendliness, convenient recycle, and low cost, which renders them potentially viable in treating real wastewater containing FQs.

Comparative evaluation of the mechanisms of toxicity of graphene oxide and graphene oxide quantum dots to blue-green algae Microcystis aeruginosa in the aquatic environment

Due to the diverse applications, graphene-family nanomaterials (GFNs) have a high probability of release into the aquatic system, potentially posing risks to the aquatic environment. The acute effects on single-celled Microcystis aeruginosa by graphene oxide (GO) or graphene oxide quantum dots (GOQDs) were compared in the present study. GOQDs dispersed more effectively in water than GO at all pH values tested. The 96-hour median effective concentration (EC₅₀) of GO and GOQDs were determined to be 49.32 and 22.46 mg/L, respectively. Both GO and GOQDs were internalized by heteroagglomeration and envelopment processes, with GOQDs inducing stronger upregulation of cell permeability, plasmolysis and lipid bodies than GO. Cracking of thylakoid layers, disappearance of nucleoid, and disintegration of cell infrastructure were observed at higher concentrations. In comparison to GO, GOQDs induced higher reactive oxygen species (ROS) and malondialdehyde (MDA) and disrupted antioxidant enzymes, leading to the inhibition of cellular contents such as chlorophyll a and proteins. Furthermore, both GO and GOQDs adsorbed nutrients from the algal medium, resulting in nutrient depletion-induced indirect toxicity, with GOQDs depleting more nutrients than GO. The current study provides new understanding of nanotoxicity of GO and GOQD and aids in the potential risks of nanomaterials in aquatic environments.

A critical review on the role of abiotic factors on the transformation, environmental identity and toxicity of engineered nanomaterials in aquatic environment

Engineered nanomaterials (ENMs) are at the forefront of many technological breakthroughs in science and engineering. The extensive use of ENMs in several consumer products has resulted in their release to the aquatic environment. ENMs entering the aquatic ecosystem undergo a dynamic transformation as they interact with organic and inorganic constituents present in aquatic environment, specifically abiotic factors such as NOM and clay minerals, and attain an environmental identity. Thus, a greater understanding of ENM-abiotic factors interactions is required for an improved risk assessment and sustainable management of ENMs contamination in the aquatic environment. This review integrates fundamental aspects of ENMs transformation in aquatic environment as impacted by abiotic factors, and delineates the recent advances in bioavailability and ecotoxicity of ENMs in relation to risk assessment for ENMs-contaminated aquatic ecosystem. It specifically discusses the mechanism of transformation of different ENMs (metals, metal oxides and carbon based nanomaterials) following their interaction with the two most common abiotic factors NOM and clay minerals present within the aquatic ecosystem. The review critically discusses the impact of these mechanisms on the altered ecotoxicity of ENMs including the impact of such transformation at the genomic level. Finally, it identifies the gaps in our current understanding of the role of abiotic factors on the transformation of ENMs and paves the way for the future research areas.

The detection and characterization techniques for the interaction between graphene oxide and natural colloids: A review

The high dispersibility of graphene oxide (GO) and the universality of natural colloids (clay minerals, (hydr)oxides of Al, Fe, silica, etc.) make them interact easily. Many kinds of analytical methods have been used to study the interaction between GO and natural colloids. This review provides a comprehensive overview of analytical methods for the detection and quantification of interaction process. We highlighted the influence of the most relevant environmental factors (ionic strength, pH, etc.) on batch experiment, quartz crystal microbalance with dissipation monitoring measurements, and column experiments. Besides, the benefits and drawbacks of spectroscopic, microscopic techniques, theoretical models, calculation and time-resolved dynamic light scattering methods also have discussed in this work. This review can give some guidance to researchers in their selection and combination of the technique for the research of the interaction between GO and natural colloids.

Nanomaterial sulfonated graphene oxide advances the tolerance against nitrate and ammonium toxicity by regulating chloroplastic redox balance, photochemistry of photosystems and antioxidant capacity in Triticum aestivum

The current study was designed to assess nanomaterial sulfonated graphene oxide (SGO) potential in improving tolerance of wheat chloroplasts against nitrate (NS) and ammonium (AS) toxicity. Triticum aestivum cv. Ekiz was grown under SGOs (50-250-500 mg L^-1) with/without 140 mM NS and 5 mM AS stress. SGOs were eliminated the adverse effects produced by stress on chlorophyll fluorescence, potential photochemical efficiency and physiological state of the photosynthetic apparatus. SGO reversed the negative effects on these parameters. Upon SGOs exposure, the induced expression levels of photosystems-related reaction center proteins were observed. SGOs reverted radical accumulation triggered by NS by enabling the increased superoxide dismutase (SOD) activity and ascorbate (AsA) regeneration. Under AS, the turnover of both AsA and glutathione (GSH) was maintained by 50-250 mg L^-1 SGO by increasing the enzymes and non-enzymes related to AsA-GSH cycle. 500 mg L^-1 SGO prevented the radical over-accumulation produced by AS via the regeneration of AsA and peroxidase (POX) activity rather than GSH regeneration. 50-250 mg L^-1 SGO protected from the NS+AS-induced disruptions through the defense pathways connected with AsA-GSH cycle represented the high rates of AsA/DHA and, GSH/GSSG and GSH redox state. Our findings specified that SGO to NS and AS-stressed wheat provides a new potential tool to advance the tolerance mechanism.

Study on the performance of laterite in removing graphene oxide contaminants from aqueous solution

To remove graphene oxide contaminant from aqueous solution, laterite was used as an adsorbent to conduct batch adsorption experiments on graphene oxide aqueous solutions. The effects of pH, adsorbent mass, graphene oxide initial concentration, contact time, and temperature on graphene oxide adsorption by laterite were studied predominantly. The results show that graphene oxide adsorption by laterite strongly depends on pH, the kinetic data conforms to the second-order kinetic model, and the isotherm data are in line with Langmuir and Freundlich models. Moreover, temperature increment is more conducive to improving the adsorption capacity. Combined with scanning electron microscopy, transmission electron microscopy, atomic force microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and Raman microscopic tests, the internal changes of samples before and after adsorption were further revealed. The comprehensive analysis of the above experimental results shows that laterite is a good material, which can effectively remove graphene oxide contamination from aqueous solutions.

Simulating and Predicting Adsorption of Organic Pollutants onto Black Phosphorus Nanomaterials

Layered black phosphorus (BP) has exhibited exciting application prospects in diverse fields. Adsorption of organics onto BP may influence environmental behavior and toxicities of both organic pollutants and BP nanomaterials. However, contributions of various intermolecular interactions to the adsorption remain unclear, and values of adsorption parameters such as adsorption energies (E_ad) and adsorption equilibrium constants (K) are lacking. Herein, molecular dynamic (MD) and density functional theory (DFT) was adopted to calculate E_ad and K values. The calculated E_ad and K values for organics adsorbed onto graphene were compared with experimental ones, so as to confirm the reliability of the calculation methods. Polyparameter linear free energy relationship (pp-LFER) models on E_ad and logK were developed to estimate contributions of different intermolecular interactions to the adsorption. The adsorption in the gaseous phase was found to be more favorable than in the aqueous phase, as the adsorbates need to overcome cohesive energies of water molecules onto BP. The affinity of the aromatics to BP was comparable to that of graphene. The pp-LFER models performed well for predicting the E_ad and K values, with external explained variance ranging from 0.90 to 0.97, and can serve as effective tools to rank adsorption capacities of organics onto BP.

Effects of environmental aging on the adsorption behavior of antibiotics from aqueous solutions in microplastic-graphene coexisting systems

The extensive use of nanofillers, such as graphene oxide (GO) and reduced graphene oxide (rGO), as plastic additives has led to the coexistence of microplastics (MPs) and nanomaterials in aquatic environments. However, there is a lack of studies on the adsorption behavior of MPs when coexisting with GO. Moreover, MPs and GO are prone to undergoing aging processes in real environments under conditions such as sunlight exposure, which changes their physicochemical properties and affects their adsorption behavior. In this study, the aging processes of MPs and GO in a real environment were simulated by ultraviolet (UV) irradiation and thermal treatments, respectively. The adsorption behavior of ciprofloxacin (CIP) on three types of MPs (polypropylene (PP), polyamide (PA), and polystyrene (PS)) before and after aging was explored. The MPs are ordered in terms of CIP adsorption capacity as aged-PA > aged-PS > aged-PP > PA > PP > PS, and the adsorption capacity of aged MPs was approximately twofold higher than that of pristine MPs. This paper also studied the adsorption performance of antibiotics in a coexisting system of aged MPs and GO/rGO, and the tetracycline (TC) adsorption capacity was increased by ~336% in aged PP-GO and ~100% in an aged PP-rGO coexisting system. GO/rGO with high degree of oxidation and concentration in an aged- PP-GO/rGO coexisting system are more conducive to the TC adsorption, due to the contribution of oxygen-containing functional groups. Surface and partition adsorption co-occurred during the TC adsorption process. The TC adsorption behavior in the MPs-GO/rGO coexisting system was strongly dependent on the solution pH, which was more favorable under acidic (pH = 3) or alkaline (pH = 11) conditions. This study improves the understanding of the environmental behavior of MPs, graphene, and antibiotics and guides research on strategies for preventing the migration of antibiotics in MPs-GO/rGO coexisting systems.

The aggregation behaviour and mechanism of commercial graphene oxide in surface aquatic environments

In this study, we comprehensively and critically discuss the aggregation mechanism of commercial graphene oxide (CGO) in surface aquatic environments. The aggregation kinetics and critical coagulation concentration of CGO were obtained through time-resolved dynamic light scattering and batch techniques over a wide range of water types. By employing transmission electron microscopy and elemental mapping, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy, we studied the effects of cations in natural waters on the microstructure transformation, element content and distribution, and oxygen-containing functional group vibrations of CGO. The aggregation of CGO in natural water is induced mainly by Ca²⁺ by complexing; Na⁺, with a higher concentration, plays a more important role than Mg²⁺ in inducing aggregation via electric double layer suppression. Ca²⁺ mainly interacts with C - COOH, while Mg²⁺ has a greater effect on C - OH. Na⁺ has less effect on the oxygen-containing functional group but decreases the C/O ratio in contrast with Mg²⁺/Ca²⁺/natural water, indicating the different inducing mechanisms. This study looks forward to providing pivotal knowledge to predict the environmental fate of CGO more accurately in natural surface water.

Three-dimensional graphene encapsulated hollow CoSe2-SnSe2nanoboxes for high performance asymmetric supercapacitors

Construction of metal selenides with a large specific surface area and a hollow structure is one of the effective methods to improve the electrochemical performance of supercapacitors. However, the nano-material easily agglomerates due to the lack of support, resulting in the loss of electrochemical performance. Herein, we successfully design a three-dimensional graphene (3DG) encapsulation-protected hollow nanoboxes (CoSe₂-SnSe₂) composite aerogel (3DG/CoSe₂-SnSe₂) via a co-precipitation method coupled with self-assembly route, followed by a high temperature selenidation strategy. The obtained aerogel possesses porous 3DG conductive network, large specific surface area and plenty of reactive active sites. It could be used as a flexible and binder-free electrode after a facile mechanical compression process, which provided a high specific capacitance of 460 F g^-1at 0.5 A g^-1, good rate capability of 212.7 F g^-1at 10 A g^-1The capacitance retention rate is 80% at 2 A g^-1after 5000 cycles due to the fast electron/ion transfer and electrolyte diffusion. With the as-prepared 3DG/CoSe₂-SnSe₂as positive electrodes and the AC (activated carbon) as negative electrodes, an asymmetric supercapacitor (3DG/CoSe₂-SnSe₂//AC) was fabricated, which delivered a high specific capacity of 38 F g^-1at 1 A g^-1and an energy density of 11.89 Wh kg^-1at 749.9 W kg^-1, as well as excellent cycle stability. This work provides a new method for preparing electrode material.

Investigating the effects of biochar colloids and nanoparticles on cucumber early seedlings

Understanding about the influence of biochar colloidal and nanoscale particles on plant is limited. We therefore extracted the colloids and nanoparticles from hot pepper stalk biochar (CB600 and NB600), and examined physiological responses of cucumber early seedlings through hydroponic culture and pot experiment. CB600 had no significant effect on shoot at 500 mg/L, while it decreased root biomass and inhibited lateral root development. The biomass and root length, area, and tip number dramatically reduced after 500 mg/L NB600 treatment. Water content of NB600-exposed shoot was lower, suggesting water uptake and transfer might be hindered. For resisting exposure stress, root hair number and length increased. Even, the study observed swelling and hyperplasia of root hairs after direct exposure of CB600 and NB600. These adverse effects might be associated with the contact and adhesion of CB600 and NB600 with sharp edges to root surface. For a low concentration of 50 mg/L, NB600 did not influence cucumber early seedlings. In soil, CB600 and NB600 did not cause inhibitory effect at relatively high contents of 500 mg/kg and 2000 mg/kg. This study provides useful information for understanding phytotoxicity and environmental risk of biochar colloids and nanoparticles, which has significant implications with regard to biochar application safety.

Enhanced Performance of PVDF Composite Ultrafiltration Membrane via Degradation of Collagen-Modified Graphene Oxide

The collagen obtained from chrome leather waste can be used to modify graphene oxide (GO) to prepare polyvinylidene fluoride (PVDF) composite ultrafiltration membranes, a process that is conducive to the recovery of leather waste, comprehensive utilization of GO and improved performance of the membrane. In this paper, collagen-modified GO (CGO) was prepared by degradation of collagen from chrome leather waste and used to prepare a PVDF composite ultrafiltration membrane. The results show that the carboxyl content of CGO and dispersion were improved. The water flux and flux recovery rate of the modified ultrafiltration membrane were improved. The bovine serum albumin (BSA) intercepted on the membrane surface was easy to clean and the antifouling performance improved. The performance of the membrane decreased when the GO content exceeded 0.75 wt%, while CGO can reach 1.0 wt% without agglomeration due to its good dispersion.

Multigenerational selection towards longevity changes the protective role of vitamin C against graphene oxide-induced oxidative stress in house crickets

This research was designed to investigate changes that can arise in an invertebrate organism due to stress caused by a strong prooxidant, graphene oxide (GO), and a potent antioxidant, vitamin C. The study aimed to investigate if vitamin C may support convalescence after chronic GO intoxication. We investigated the toxicity of chronic dietary graphene oxide administration in house cricket (Acheta domesticus) types: wild and selected for longevity (with a better developed antioxidant system, conducive to long life). Vitamin C was applied immediately after cessation of graphene oxide intoxication to check if it can support the remedial effect. The condition of cells, DNA stability, catalase activity, and the reproduction potential, measured as the Vitellogenin (Vg) protein expression level, were investigated in control and GO treated groups, recovery groups (-GO), and recovery groups with Vit. C (-GO + Vit.C). In this study vitamin C had no evident remedial effect on the house crickets exposed to graphene oxide. Most probably, the mechanism of vitamin C action, in case of intoxication with nanoparticles, is much more complicated. In the context of the results obtained, it is worth considering whether Vit. C, applied after GO intoxication, causes further disturbance of homeostasis in terms of the cells' redox potential.