Search

Nanomaterials have attracted research attention due to their unique properties, which have also made them increasingly useful for various applications, including remediation technologies. In this work, we tried to explore the aging phenomenon of several newly developed nanoscale zero-valent iron (nZVI) particles containing 0.25, 1, and 5% sulfur and to monitor the possible toxicity changes related to the nZVI particles before and during the aging period. We used several relevant techniques for monitoring nZVI aging, including transmission electron microscopy, X-ray powder diffraction, and particle size analysis. The toxicity of the nZVI particles was monitored using a new oxidative stress assay based on lipid peroxidation, a simple bacterial cultivation test. A test using activated sludge respiration and phospholipid fatty acid analysis of microbial populations was also employed. The results of the material analyses showed that the sulfidated nZVI particles were more stable than bare nZVI particles in terms of Fe0 content and particle diameter. The stability was more pronounced with the increasing content of sulfur in the nanoparticles; the content of α-Fe was only 35.3% in the nZVI particles compared with 78.6% in the 5% sulfur-doped nanoparticles after 60 days of aging. The results of the oxidative stress assay revealed that the toxicity was also lower with increasing sulfur content; nevertheless, the oxidative stress marker increased substantially after 7 days of aging, reaching a similar level to that caused by bare nZVI in some cases. Other results showed that even incubation in media used for the respective tests caused extensive aging; therefore, this information must be considered before the selection of toxicity assays for nanomaterial evaluation.

A facile and eco-friendly approach is developed for the synthesis of a poly(3-hydroxybutyrate)–chitosan (PHB–chit) polymer conjugate, which is an ideal material for the synthesis of safer gold nanoparticles (nAu). The synthesized products are characterized by various electron-based, optical and spectroscopic techniques including the catalytic activity and the stability/toxicity of nAu. In contrast to the conventional synthesis approaches, the use of PHB–chit results in generation of a highly stable and size-controlled nAu material that exhibits important catalytic activity towards the reduction of 4-nitrophenol (4-NP) to 4-aminophenol, and at the same time shows no toxicity against living bacterial systems such as Escherichia coli or Staphylococcus aureus. The synthesis route reported herein would inspire future developments that circumvent toxicity issues of relevance to living systems while performing common catalytic experimentation.

Tree gums are a class of abundantly available carbohydrate polymers that have not been explored thoroughly in film fabrication for food packaging. Films obtained from pristine tree gums are often brittle, hygroscopic, and lack mechanical strength. This study focuses on the chemical modification of gum kondagogu using long-chain alkenyl groups of dodecenyl succinic anhydride (DDSA), an esterifying agent that introduces a 12-carbon hydrophobic chain to the kondagogu structure. The esterification reaction was confirmed by 1H nuclear magnetic resonance and Fourier-transform infrared spectroscopy. The effect of nano-cellulose as an additive on various film properties was investigated. The developed films were characterized for their mechanical, morphological, optical, barrier, antibacterial, and biodegradable properties. The inclusion of long-chain carbon groups acted as internal plasticizers and resulted in an amorphous structure with better film-forming ability, improved hydrophobicity, and higher elongation at break values. The modified films exhibited antibacterial properties and excellent biodegradability under aerobic conditions.

Nanoremediation with iron (Fe) nanomaterials opens new doors for treating contaminated soil and groundwater, but is also accompanied by new potential risks as large quantities of engineered nanomaterials are introduced into the environment. In this study, we have assessed the ecotoxicity of four engineered Fe nanomaterials, specifically, Nano-Goethite, Trap-Ox Fe-zeolites, Carbo-Iron® and FerMEG12, developed within the European FP7 project NanoRem for sub-surface remediation towards a test battery consisting of eight ecotoxicity tests on bacteria (V. fisheri, E. coli), algae (P. subcapitata, Chlamydomonas sp.), crustaceans (D. magna), worms (E. fetida, L. variegatus) and plants (R. sativus, L. multiflorum). The tested materials are commercially available and include Fe oxide and nanoscale zero valent iron (nZVI), but also hybrid products with Fe loaded into a matrix. All but one material, a ball milled nZVI (FerMEG12), showed no toxicity in the test battery when tested in concentrations up to 100 mg/L, which is the cutoff for hazard labeling in chemicals regulation in Europe. However it should be noted that Fe nanomaterials proved challenging to test adequately due to their turbidity, aggregation and sedimentation behavior in aqueous media. This paper provides a number of recommendations concerning future testing of Fe nanomaterials and discusses environmental risk assessment considerations related to these.

The objective of present study was to develop multifunctional and wearable electrically conductive fabrics with acceptable comfort properties by in-situ deposition of silver particles. The effect of silver nitrate concentration and number of dips was investigated for change in electrical conductivity, EMI shielding, and antimicrobial properties of coated fabrics. The dynamic light scattering and SEM analysis were employed to study the morphology of deposited silver particles. The EMI shielding was found to increase with increase in concentration of silver particles. Later, the comfort and mechanical properties were studied. No significant decrease in air permeability and water vapor permeability was observed due to partial coverage of fabric pores by coating of silver particles. Moreover, the coated fabrics also showed promising behavior toward antimicrobial properties. When the durability of coated fabrics was examined against washing, the application of binder provided good retention of silver p...

Multifunctional nanoparticles for magnetic hyperthermia which simultaneously display antibacterial properties promise to decrease bacterial infections co-localized with cancers. Current methods synthesize such particles by multi-step procedures, and systematic comparisons of antibacterial properties between coatings, as well as measurements of specific absorption rate (SAR) during magnetic hyperthermia are lacking. Here we report the novel simple method for synthesis of magnetic nanoparticles with shells of oleic acid (OA), polyethyleneimine (PEI) and polyethyleneimine-methyl cellulose (PEI-mC). We compare their antibacterial properties against single gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria as well as biofilms. Magnetite nanoparticles (MNPs) with PEI-methyl cellulose were found to be most effective against both S. aureus and E. coli with concentration for 10% growth inhibition (EC10) of

Despite the ground-breaking potential of nanomaterials, their safe and sustainable incorporation into an array of industrial markets prompts a deep and clear understanding of their potential toxicity for both humans and the environment. Among the many materials with great potential, graphene has shown promise in a variety of applications; however, the impact of graphene based products on living systems remains poorly understood. In this paper, we illustrate that via exploiting the tribological properties of graphene nanosheets, we can successfully improve both the frictional behaviour and the anti-wear capacity of lubricant oil for mechanical transmission. By virtue of reducing friction and enhancing lubricant lifetimes, we can forecast a reduction in friction based energy loss, in addition to a decrease in the carbon footprint of vehicles. The aforementioned positive environmental impact is further strengthened considering the lack of acute toxicity found in our extensive in vitro investigation, in which both eukaryotic and prokaryotic cells were tested. Collectively, our body of work suggests that by the use of safe nanoadditives we could contribute to reducing the environmental impact of transportation and therein take a positive step towards a more sustainable automotive sector. The workflow proposed here for the evaluation of human and environmental toxicity will allow for the study of nanosized bare graphene material and can be broadly applied to the translation of graphene-based nanomaterials into the market.

Recently, the green synthesis of metal nanoparticles has attracted wide attention due to its feasibility and very low environmental impact. This approach was applied in this study to synthesise nanoscale gold (Au), platinum (Pt), palladium (Pd), silver (Ag) and copper oxide (CuO) materials in simple aqueous media using the natural polymer gum karaya as a reducing and stabilising agent. The nanoparticles’ (NPs) zeta-potential, stability and size were characterised by Zetasizer Nano, UV–Vis spectroscopy and by electron microscopy. Moreover, the biological effect of the NPs (concentration range 1.0–20.0 mg/L) on a unicellular green alga (Chlamydomonas reinhardtii) was investigated by assessing algal growth, membrane integrity, oxidative stress, chlorophyll (Chl) fluorescence and photosystem II photosynthetic efficiency. The resulting NPs had a mean size of 42 (Au), 12 (Pt), 1.5 (Pd), 5 (Ag) and 180 (CuO) nm and showed high stability over 6 months. At concentrations of 5 mg/L, Au and Pt NPs only slightly reduced algal growth, while Pd, Ag and CuO NPs completely inhibited growth. Ag, Pd and CuO NPs showed strong biocidal properties and can be used for algae prevention in swimming pools (CuO) or in other antimicrobial applications (Pd, Ag), whereas Au and Pt lack these properties and can be ranked as harmless to green alga. Electronic supplementary material The online version of this article (10.1186/s11671-018-2575-5) contains supplementary material, which is available to authorized users.

The most challenging task in the preparation of magnetic poly(N-isopropylacrylamide) (Fe3O4-PNIPAAm) nanocomposites for bio-applications is to maximise their reactivity and stability. Emulsion polymerisation, in situ precipitation and physical addition were used to produce Fe3O4-PNIPAAm-1, Fe3O4-PNIPAAm-2 and Fe3O4-PNIPAAm-3, respectively. Their properties were characterised using scanning electron microscopy (morphology), zeta-potential (surface charge), thermogravimetric analysis (stability), vibrating sample magnetometry (magnetisation) and dynamic light scattering. Moreover, we investigated the antibacterial effect of each nanocomposite against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus. Both Fe3O4-PNIPAAm-1 and Fe3O4-PNIPAAm-2 nanocomposites displayed high thermal stability, zeta potential and magnetisation values, suggesting stable colloidal systems. Overall, the presence of Fe3O4-PNIPAAm nanocomposites, even at lower concentrations, caused significant damage to both E. coli and S. aureus DNA and led to a decrease in cell viability. Fe3O4-PNIPAAm-1 displayed a stronger antimicrobial effect against both bacterial strains than Fe3O4-PNIPAAm-2 and Fe3O4-PNIPAAm-3. Staphylococcus aureus was more sensitive than E. coli to all three magnetic PNIPAAm nanocomposites.