Editorial

150 KiB

Open AccessEditorial

Engineered Nanomaterials in the Environment

by Jonathan D. Judy and Paul Bertsch

Nanomaterials 2016, 6(6), 106; https://doi.org/10.3390/nano6060106 - 06 Jun 2016

Cited by 3 | Viewed by 3722

This Special Issue of Nanomaterials, “Engineered Nanomaterials in the Environment”, is comprised of one communication and ﬁve research articles.[...] Full article

(This article belongs to the Special Issue Engineered Nanomaterials in the Environment)

Research

Jump to: Editorial

3859 KiB

Open AccessArticle

Separation of Bacteria, Protozoa and Carbon Nanotubes by Density Gradient Centrifugation

by Monika Mortimer, Elijah J. Petersen, Bruce A. Buchholz and Patricia A. Holden

Nanomaterials 2016, 6(10), 181; https://doi.org/10.3390/nano6100181 - 12 Oct 2016

Cited by 21 | Viewed by 9687

Abstract

Sustainable production and use of carbon nanotube (CNT)-enabled materials require efficient assessment of CNT environmental hazards, including the potential for CNT bioaccumulation and biomagnification in environmental receptors. Microbes, as abundant organisms responsible for nutrient cycling in soil and water, are important ecological receptors [...] Read more.

Sustainable production and use of carbon nanotube (CNT)-enabled materials require efficient assessment of CNT environmental hazards, including the potential for CNT bioaccumulation and biomagnification in environmental receptors. Microbes, as abundant organisms responsible for nutrient cycling in soil and water, are important ecological receptors for studying the effects of CNTs. Quantification of CNT association with microbial cells requires efficient separation of CNT-associated cells from individually dispersed CNTs and CNT agglomerates. Here, we designed, optimized, and demonstrated procedures for separating bacteria (Pseudomonas aeruginosa) from unbound multiwall carbon nanotubes (MWCNTs) and MWCNT agglomerates using sucrose density gradient centrifugation. We demonstrate separation of protozoa (Tetrahymena thermophila) from MWCNTs, bacterial agglomerates, and protozoan fecal pellets by centrifugation in an iodixanol solution. The presence of MWCNTs in the density gradients after centrifugation was determined by quantification of ¹⁴C-labeled MWCNTs; the recovery of microbes from the density gradient media was confirmed by optical microscopy. Protozoan intracellular contents of MWCNTs and of bacteria were also unaffected by the designed separation process. The optimized methods contribute to improved efficiency and accuracy in quantifying MWCNT association with bacteria and MWCNT accumulation in protozoan cells, thus supporting improved assessment of CNT bioaccumulation. Full article

(This article belongs to the Special Issue Engineered Nanomaterials in the Environment)

► Show Figures

Figure 1

3459 KiB

Open AccessArticle

Aggregation and Colloidal Stability of Commercially Available Al₂O₃ Nanoparticles in Aqueous Environments

by Julie Mui, Jennifer Ngo and Bojeong Kim

Nanomaterials 2016, 6(5), 90; https://doi.org/10.3390/nano6050090 - 13 May 2016

Cited by 51 | Viewed by 7899

Abstract

The aggregation and colloidal stability of three, commercially-available, gamma-aluminum oxide nanoparticles (γ-Al₂O₃ NPs) (nominally 5, 10, and 20–30 nm) were systematically examined as a function of pH, ionic strength, humic acid (HA) or clay minerals (e.g., montmorillonite) concentration using dynamic [...] Read more.

The aggregation and colloidal stability of three, commercially-available, gamma-aluminum oxide nanoparticles (γ-Al₂O₃ NPs) (nominally 5, 10, and 20–30 nm) were systematically examined as a function of pH, ionic strength, humic acid (HA) or clay minerals (e.g., montmorillonite) concentration using dynamic light scattering and transmission electron microscopy techniques. NPs possess pH-dependent surface charges, with a point of zero charge (PZC) of pH 7.5 to 8. When pH < PZC, γ-Al₂O₃ NPs are colloidally stable up to 100 mM NaCl and 30 mM CaCl₂. However, significant aggregation of NPs is pronounced in both electrolytes at high ionic strength. In mixed systems, both HA and montmorillonite enhance NP colloidal stability through electrostatic interactions and steric hindrance when pH ≤ PZC, whereas their surface interactions are quite limited when pH > PZC. Even when pH approximates PZC, NPs became stable at a HA concentration of 1 mg·L⁻¹. The magnitude of interactions and dominant sites of interaction (basal planes versus edge sites) are significantly dependent on pH because both NPs and montmorillonite have pH-dependent (conditional) surface charges. Thus, solution pH, ionic strength, and the presence of natural colloids greatly modify the surface conditions of commercial γ-Al₂O₃ NPs, affecting aggregation and colloidal stability significantly in the aqueous environment. Full article

(This article belongs to the Special Issue Engineered Nanomaterials in the Environment)

► Show Figures

Figure 1

1390 KiB

Open AccessCommunication

Gold Nanomaterial Uptake from Soil Is Not Increased by Arbuscular Mycorrhizal Colonization of Solanum Lycopersicum (Tomato)

by Jonathan D. Judy, Jason K. Kirby, Mike J. McLaughlin, Timothy Cavagnaro and Paul M. Bertsch

Nanomaterials 2016, 6(4), 68; https://doi.org/10.3390/nano6040068 - 13 Apr 2016

Cited by 10 | Viewed by 4681

Abstract

Bioaccumulation of engineered nanomaterials (ENMs) by plants has been demonstrated in numerous studies over the past 5–10 years. However, the overwhelming majority of these studies were conducted using hydroponic systems and the degree to which the addition of the biological and chemical components [...] Read more.

Bioaccumulation of engineered nanomaterials (ENMs) by plants has been demonstrated in numerous studies over the past 5–10 years. However, the overwhelming majority of these studies were conducted using hydroponic systems and the degree to which the addition of the biological and chemical components present in the soil might fundamentally alter the potential of plant bioaccumulation of ENMs is unclear. Here, we used two genotypes of Solanum lycopersicum (tomato), reduced mycorrhizal colonization (rmc), a mutant which does not allow arbuscular mycorrhizal fungi (AMF) colonization, and its progenitor, 76R, to examine how colonization by AMF alters trends of gold ENM bioaccumulation from a natural soil. Gold was taken up and bioaccumulated by plants of both genotypes. Gold concentrations were significantly higher in the rmc treatment although this was likely attributable to the large differences in biomass between the 76R and rmc plants. Regardless, there was little evidence that AMF played a significant role in trafficking Au ENMs into the plants. Furthermore, despite very low NH₄NO₃ extractable Au concentrations, Au accumulated at the root-soil interface. Although this observation would seem to suggest that ENMs may have potential to influence this particularly biologically active and important soil compartment, we observed no evidence of this here, as the 76R plants developed a robust AMF symbiosis despite accumulation of Au ENMs at the rhizoplane. Full article

(This article belongs to the Special Issue Engineered Nanomaterials in the Environment)

► Show Figures

Graphical abstract

2450 KiB

Open AccessArticle

Nanoparticles Composed of Zn and ZnO Inhibit Peronospora tabacina Spore Germination in vitro and P. tabacina Infectivity on Tobacco Leaves

by George Wagner, Victor Korenkov, Jonathan D. Judy and Paul M. Bertsch

Nanomaterials 2016, 6(3), 50; https://doi.org/10.3390/nano6030050 - 16 Mar 2016

Cited by 58 | Viewed by 5841

Abstract

Manufactured nanoparticles (NPs) are increasingly being used for commercial purposes and certain NP types have been shown to have broad spectrum antibacterial activity. In contrast, their activities against fungi and fungi-like oomycetes are less studied. Here, we examined the potential of two types [...] Read more.

Manufactured nanoparticles (NPs) are increasingly being used for commercial purposes and certain NP types have been shown to have broad spectrum antibacterial activity. In contrast, their activities against fungi and fungi-like oomycetes are less studied. Here, we examined the potential of two types of commercially available Zn NPs (Zn NPs and ZnO NPs) to inhibit spore germination and infectivity on tobacco leaves resulting from exposure to the fungi-like oomycete pathogen Peronospora tabacina (P. tabacina). Both types of NPs, as well as ZnCl₂ and bulk ZnO control treatments, inhibited spore germination compared to a blank control. ZnO ENMs were shown to be a much more powerful suppressor of spore germination and infectivity than bulk ZnO. ZnO and Zn NPs significantly inhibited leaf infection at 8 and 10 mg·L⁻¹, respectively. Both types of NPs were found to provide substantially higher concentration dependent inhibition of spore germination and infectivity than could be readily explained by the presence of dissolved Zn. These results suggest that both NP types have potential for use as economic, low-dose, potentially non-persistent anti-microbial agents against the oomycete P. tabacina. Full article

(This article belongs to the Special Issue Engineered Nanomaterials in the Environment)

► Show Figures

Graphical abstract

2095 KiB

Open AccessArticle

Toxicity Testing of Pristine and Aged Silver Nanoparticles in Real Wastewaters Using Bioluminescent Pseudomonas putida

by Florian Mallevre, Camille Alba, Craig Milne, Simon Gillespie, Teresa F. Fernandes and Thomas J. Aspray

Nanomaterials 2016, 6(3), 49; https://doi.org/10.3390/nano6030049 - 11 Mar 2016

Cited by 29 | Viewed by 5216

Abstract

Impact of aging on nanoparticle toxicity in real matrices is scarcely investigated due to a lack of suitable methodologies. Herein, the toxicity of pristine and aged silver nanoparticles (Ag NPs) to a bioluminescent Pseudomonas putida bioreporter was measured in spiked crude and final [...] Read more.

Impact of aging on nanoparticle toxicity in real matrices is scarcely investigated due to a lack of suitable methodologies. Herein, the toxicity of pristine and aged silver nanoparticles (Ag NPs) to a bioluminescent Pseudomonas putida bioreporter was measured in spiked crude and final wastewater samples (CWs and FWs, respectively) collected from four wastewater treatment plants (WWTPs). Results showed lower toxicity of pristine Ag NPs in CWs than in FWs. The effect of the matrix on the eventual Ag NP toxicity was related to multiple physico-chemical parameters (biological oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS) pH, ammonia, sulfide and chloride) based on a multivariate analysis. However, no collection site effect was concluded. Aged Ag NPs (up to eight weeks) were found less toxic than pristine Ag NPs in CWs; evident increased aggregation and decreased dissolution were associated with aging. However, Ag NPs exhibited consistent toxicity in FWs despite aging; comparable results were obtained in artificial wastewater (AW) simulating effluent. The study demonstrates the potency of performing nanoparticle acute toxicity testing in real and complex matrices such as wastewaters using relevant bacterial bioreporters. Full article

(This article belongs to the Special Issue Engineered Nanomaterials in the Environment)

► Show Figures

Figure 1

551 KiB

Open AccessArticle

EU Regulation of Nanobiocides: Challenges in Implementing the Biocidal Product Regulation (BPR)

by Anna Brinch, Steffen Foss Hansen, Nanna B. Hartmann and Anders Baun

Nanomaterials 2016, 6(2), 33; https://doi.org/10.3390/nano6020033 - 16 Feb 2016

Cited by 40 | Viewed by 8820

Abstract

The Biocidal Products Regulation (BPR) contains several provisions for nanomaterials (NMs) and is the first regulation in the European Union to require specific testing and risk assessment for the NM form of a biocidal substance as a part of the information requirements. Ecotoxicological [...] Read more.

The Biocidal Products Regulation (BPR) contains several provisions for nanomaterials (NMs) and is the first regulation in the European Union to require specific testing and risk assessment for the NM form of a biocidal substance as a part of the information requirements. Ecotoxicological data are one of the pillars of the information requirements in the BPR, but there are currently no standard test guidelines for the ecotoxicity testing of NMs. The overall objective of this work was to investigate the implications of the introduction of nano-specific testing requirements in the BPR and to explore how these might be fulfilled in the case of copper oxide nanoparticles. While there is information and data available in the open literature that could be used to fulfill the BPR information requirements, most of the studies do not take the Organisation for Economic Co-operation and Development’s nanospecific test guidelines into consideration. This makes it difficult for companies as well as regulators to fulfill the BPR information requirements for nanomaterials. In order to enable a nanospecific risk assessment, best practices need to be developed regarding stock suspension preparation and characterization, exposure suspensions preparation, and for conducting ecotoxicological test. Full article

(This article belongs to the Special Issue Engineered Nanomaterials in the Environment)

► Show Figures

Figure 1

1087 KiB

Open AccessArticle

Organic Phase Change Nanoparticles for in-Product Labeling of Agrochemicals

by Miao Wang, Binh Duong and Ming Su

Nanomaterials 2015, 5(4), 1810-1819; https://doi.org/10.3390/nano5041810 - 28 Oct 2015

Cited by 11 | Viewed by 5959

Abstract

There is an urgent need to develop in-product covert barcodes for anti-counterfeiting of agrochemicals. This paper reports a new organic nanoparticle-based in-product barcode system, in which a panel of organic phase change nanoparticles is added as a barcode into in a variety of [...] Read more.

There is an urgent need to develop in-product covert barcodes for anti-counterfeiting of agrochemicals. This paper reports a new organic nanoparticle-based in-product barcode system, in which a panel of organic phase change nanoparticles is added as a barcode into in a variety of chemicals (herein agrochemicals). The barcode is readout by detecting melting peaks of organic nanoparticles using differential scanning calorimetry. This method has high labeling capacity due to small sizes of nanoparticles, sharp melting peaks, and large scan range of thermal analysis. The in-product barcode can be effectively used to protect agrochemical products from being counterfeited due to its large coding capacity, technical readiness, covertness, and robustness. Full article

(This article belongs to the Special Issue Engineered Nanomaterials in the Environment)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Engineered Nanomaterials in the Environment

Share This Special Issue

Special Issue Editors

Special Issue Information

Keywords

Published Papers (8 papers)

Editorial

Research

Further Information

Guidelines

MDPI Initiatives

Follow MDPI