Stable isotopic tracing-a way forward for nanotechnology

Zn0-Induced Cytotoxicity and Mitochondrial Stress in Microglia: Implications of the Protective Role of Immunoglobulin G In Vitro

Background

Zinc (Zn), an essential micronutrient, regulates and maintains neurological functions. However, both Zn deficiency and excess can cause oxidative stress and neurodegenerative diseases. As previously reported, immunoglobulin G (IgG) can modulate oxidative stress in various disorders.

Aims

To investigate whether IgG treatment can alleviate oxidative stress caused by Zn0 on microglia in vitro.

Study Design

In vitro study.

Methods

The feasibility of Zn0 treatment was evaluated using the MTS assay. Oxidative stress following treatment with Zn0, either alone or with IgG supplementation, was determined with dihydrorhodamine 123 staining. Flow cytometry was employed to ascertain the intracellular protein levels of TRIM21, PINK, PARKIN, MFN2, Beclin-1, and active LC3B.

Methods

The feasibility of Zn0 treatment was evaluated using the MTS assay. Oxidative stress following treatment with Zn0, either alone or with IgG supplementation, was determined with dihydrorhodamine 123 staining. Flow cytometry was employed to ascertain the intracellular protein levels of TRIM21, PINK, PARKIN, MFN2, Beclin-1, and active LC3B. Results: In silico screening confirmed the association between Zn0 cytotoxicity and apoptosis. Furthermore, oxidative stress was identified as a critical mechanism that underlies Zn0 neurotoxicity. The in silico analysis revealed that Zn can interact with the constant region of the Ig heavy chain, suggesting a potential role for IgG in alleviating Zn0-induced cytotoxicity. Experimental findings supported this hypothesis, as IgG administration significantly reduced Zn0-induced mitochondrial stress in a dose-dependent manner. The upregulation of PINK1 levels by Zn0 exposure suggests that mitochondrial injury promotes mitophagy. Interestingly, Zn0 decreased TRIM21 levels, which is reversed by IgG administration.

Conclusion

These findings elucidate the cellular responses to Zn0 and highlight the potential use of intravenous immunoglobulin in mitigating the adverse effects of acute Zn0 exposure.

Precisely Identifying the Sources of Magnetic Particles by Hierarchical Classification-Aided Isotopic Fingerprinting

Magnetic particles (MPs), with magnetite (Fe3O4) and maghemite (γ-Fe2O3) as the most abundant species, are ubiquitously present in the natural environment. MPs are among the most applied engineered particles and can be produced incidentally by various human activities. Identification of the sources of MPs is crucial for their risk assessment and regulation, which, however, is still an unsolved problem. Here, we report a novel approach, hierarchical classification-aided stable isotopic fingerprinting, to address this problem. We found that naturally occurring, incidental, and engineered MPs have distinct Fe and O isotopic fingerprints due to significant Fe/O isotope fractionation during their generation processes, which enables the establishment of an Fe-O isotopic library covering complex sources. Furthermore, we developed a three-level machine learning model that not only can distinguish the sources of MPs with a high precision (94.3%) but also can identify the multiple species (Fe3O4 or γ-Fe2O3) and synthetic routes of engineered MPs with a precision of 81.6%. This work represents the first reliable strategy for the precise source tracing of particles with multiple species and complex sources.

Human Epidermal Zinc Concentrations after Topical Application of ZnO Nanoparticles in Sunscreens

Zinc oxide nanoparticle (ZnO NP)-based sunscreens are generally considered safe because the ZnO NPs do not penetrate through the outermost layer of the skin, the stratum corneum (SC). However, cytotoxicity of zinc ions in the viable epidermis (VE) after dissolution from ZnO NP and penetration into the VE is ill-defined. We therefore quantified the relative concentrations of endogenous and exogenous Zn using a rare stable zinc-67 isotope (67Zn) ZnO NP sunscreen applied to excised human skin and the cytotoxicity of human keratinocytes (HaCaT) using multiphoton microscopy, zinc-selective fluorescent sensing, and a laser-ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS) methodology. Multiphoton microscopy with second harmonic generation imaging showed that 67ZnO NPs were retained on the surface or within the superficial layers of the SC. Zn fluorescence sensing revealed higher levels of labile and intracellular zinc in both the SC and VE relative to untreated skin, confirming that dissolved zinc species permeated across the SC into the VE as ionic Zn and significantly not as ZnO NPs. Importantly, the LA-ICP-MS estimated exogenous 67Zn concentrations in the VE of 1.0 ± 0.3 μg/mL are much lower than that estimated for endogenous VE zinc of 4.3 ± 0.7 μg/mL. Furthermore, their combined total zinc concentrations in the VE are much lower than the exogenous zinc concentration of 21 to 31 μg/mL causing VE cytotoxicity, as defined by the half-maximal inhibitory concentration of exogenous 67Zn found in human keratinocytes (HaCaT). This speaks strongly for the safety of ZnO NP sunscreens applied to intact human skin and the associated recent US FDA guidance.

Differentiation of carbon black from black carbon using a ternary plot based on elemental analysis

Carbon black (CB) is composed of engineered nanoparticles that are commercially produced by partial combustion of hydrocarbons. It is mainly used as a reinforcing agent in vehicle tires. Although the potential health effects of CB have been investigated extensively, some toxicological reports interchange CB with black carbon (BC), which has similar features, thereby misusing the term. BC is an undesirable byproduct of the incomplete combustion of fuels. Therefore, there is a need to differentiate CB from the unintentionally produced nanomaterials (BC) in nano-toxicity, environmental, and human health studies. To distinguish clearly CB from BC, it is important to find the key parameters from several characteristics of two substances. The fundamental physicochemical properties of commercial CB and naturally formed BC were conducted. Based on the elemental analysis, we found three key factors, which could be used to differentiate the CB from BC. And thus, herein, we propose a ternary plot of the aH/C-log(C/b)-1/H combination for use in differentiating CB from BC. The plot of the 100H/C-log(C/10)-1/H combination of elemental ratios separated the CB domain from the BC domain symmetrically. The effectiveness of the ternary chart was validated using 37 samples (nine samples in this work, 25 sample results taken from references studies, and three samples from the field). Therefore, the ternary plot could be used as a prescreening tool for distinguishing CB from BC.

Distinguishing the sources of silica nanoparticles by dual isotopic fingerprinting and machine learning

One of the key shortcomings in the field of nanotechnology risk assessment is the lack of techniques capable of source tracing of nanoparticles (NPs). Silica is the most-produced engineered nanomaterial and also widely present in the natural environment in diverse forms. Here we show that inherent isotopic fingerprints offer a feasible approach to distinguish the sources of silica nanoparticles (SiO₂ NPs). We find that engineered SiO₂ NPs have distinct Si-O two-dimensional (2D) isotopic fingerprints from naturally occurring SiO₂ NPs, due probably to the Si and O isotope fractionation and use of isotopically different materials during the manufacturing process of engineered SiO₂ NPs. A machine learning model is developed to classify the engineered and natural SiO₂ NPs with a discrimination accuracy of 93.3%. Furthermore, the Si-O isotopic fingerprints are even able to partly identify the synthetic methods and manufacturers of engineered SiO₂ NPs.

Uptake and Transformation of Silver Nanoparticles and Ions by Rice Plants Revealed by Dual Stable Isotope Tracing

Knowledge on the uptake and transformation of silver nanoparticles (AgNPs) and Ag⁺ ions by organisms is critical for understanding their toxicity. Herein, the differential uptake, transformation, and translocation of AgNPs and Ag⁺ ions in hydroponic rice ( Oryza sativa L.) is assessed in modified Hewitt (with Cl^- ions, HS(Cl)) and Hogland solutions (without Cl^- ions, HS) using dual stable isotope tracing (¹⁰⁷AgNO₃ and ¹⁰⁹AgNPs). After coexposure to ¹⁰⁷Ag⁺ ions and ¹⁰⁹AgNPs at 50 μg L^-1 (as Ag for both) for 14 days, a stimulatory effect was observed on root elongation (increased by 68.8 and 71.9% for HS(Cl) and HS, respectively). Most of the Ag⁺ ions (from ¹⁰⁷Ag⁺ ions and ¹⁰⁹AgNPs) were retained on the root surface, while the occurrence of AgNPs (from ¹⁰⁹AgNPs and ¹⁰⁷Ag⁺ ions) was observed in the root, suggesting the direct uptake of AgNPs and/or reduction of Ag⁺ ions. Higher fractions of Ag⁺ ions in the shoot suggest an in vivo oxidation of AgNPs. These results demonstrated the intertransformation between Ag⁺ ions and AgNPs and the role of AgNPs as carriers and sources of Ag⁺ ions in organisms, which is helpful for understanding the fate and toxicology of Ag.

Evaluating the mobility of polymer-stabilised zero-valent iron nanoparticles and their potential to co-transport contaminants in intact soil cores

The use of zero-valent iron nanoparticles (nZVI) has been advocated for the remediation of both soils and groundwater. A key parameter affecting nZVI remediation efficacy is the mobility of the particles as this influences the reaction zone where remediation can occur. However, by engineering nZVI particles with increased stability and mobility we may also inadvertently facilitate nZVI-mediated contaminant transport away from the zone of treatment. Previous nZVI mobility studies have often been limited to model systems as the presence of background Fe makes detection and tracking of nZVI in real systems difficult. We overcame this problem by synthesising Fe-59 radiolabelled nZVI. This enabled us to detect and quantify the leaching of nZVI-derived Fe-59 in intact soil cores, including a soil contaminated by Chromated-Copper-Arsenate. Mobility of a commercially available nZVI was also tested. The results showed limited mobility of both nanomaterials; <1% of the injected mass was eluted from the columns and most of the radiolabelled nZVI remained in the surface soil layers (the primary treatment zone in this contaminated soil). Nevertheless, the observed breakthrough of contaminants and nZVI occurred simultaneously, indicating that although the quantity transported was low in this case, nZVI does have the potential to co-transport contaminants. These results show that direct injection of nZVI into the surface layers of contaminated soils may be a viable remediation option for soils such as this one, in which the mobility of nZVI below the injection/remediation zone was very limited. This Fe-59 experimental approach can be further extended to test nZVI transport in a wider range of contaminated soil types and textures and using different application methods and rates. The resulting database could then be used to develop and validate modelling of nZVI-facilitated contaminant transport on an individual soil basis suitable for site specific risk assessment prior to nZVI remediation.

Surface modification-mediated biodistribution of ¹³C-fullerene C₆₀ in vivo

BACKGROUND

Functionalization is believed to have a considerable impact on the biodistribution of fullerene in vivo. However, a direct comparison of differently functionalized fullerenes is required to prove the hypothesis. The purpose of this study was to investigate the influences of surface modification on the biodistribution of fullerene following its exposure via several routs of administration.

METHODS

(13)C skeleton-labeled fullerene C60 ((13)C-C60) was functionalized with carboxyl groups ((13)C-C60-COOH) or hydroxyl groups ((13)C-C60-OH). Male ICR mice (~25 g) were exposed to a single dose of 400 μg of (13)C-C60-COOH or (13)C-C60-OH in 200 μL of aqueous 0.9% NaCl solution by three different exposure pathways, including tail vein injection, gavage and intraperitoneal exposure. Tissue samples, including blood, heart, liver, spleen, stomach, kidneys, lungs, brain, large intestine, small intestine, muscle, bone and skin were subsequently collected, dissected, homogenized, lyophilized, and analyzed by isotope ratio mass spectrometry.

RESULTS

The liver, bone, muscle and skin were found to be the major target organs for C60-COOH and C60-OH after their intravenous injection, whereas unmodified C60 was mainly found in the liver, spleen and lung. The total uptakes in liver and spleen followed the order: C60 > > C60-COOH > C60-OH. The distribution rate over 24 h followed the order: C60 > C60-OH > C60-COOH. C60-COOH and C60-OH were both cleared from the body at 7 d post exposure. C60-COOH was absorbed in the gastrointestinal tract following gavage exposure and distributed into the heart, liver, spleen, stomach, lungs, intestine and bone tissues. The translocation of C60-OH was more widespread than that of C60-COOH after intraperitoneal injection.

CONCLUSIONS

The surface modification of fullerene C60 led to a decreased in its accumulation level and distribution rate, as well as altering its target organs. These results therefore demonstrate that the chemical functionalization of fullerene had a significant impact on its translocation and biodistribution properties. Further surface modifications could therefore be used to reduce the toxicity of C60 and improve its biocompatibility, which would be beneficial for biomedical applications.

Quantitative analysis of nanoparticle transport through in vitro blood-brain barrier models

Nanoparticle transport through the blood-brain barrier has received much attention of late, both from the point of view of nano-enabled drug delivery, as well as due to concerns about unintended exposure of nanomaterials to humans and other organisms. In vitro models play a lead role in efforts to understand the extent of transport through the blood-brain barrier, but unique features of the nanoscale challenge their direct adaptation. Here we highlight some of the differences compared to molecular species when utilizing in vitro blood-brain barrier models for nanoparticle studies. Issues that may arise with transwell systems are discussed, together with some potential alternative methodologies. We also briefly review the biomolecular corona concept and its importance for how nanoparticles interact with the blood-brain barrier. We end with considering future directions, including indirect effects and application of shear and fluidics-technologies.

Detection of Carbon Nanotubes in Indoor Workplaces Using Elemental Impurities

This study investigated three area sampling approaches for using metal impurities in carbon nanotubes (CNTs) to identify CNT releases in workplace environments: air concentrations (μg/m3), surface loadings (μg/cm2), and passive deposition rates (μg/m2/h). Correlations between metal impurities and CNTs were evaluated by collecting simultaneous colocated area samples for thermal-optical analysis (for CNTs) and ICP-MS analysis (for metals) in a CNT manufacturing facility. CNTs correlated strongly with Co (residual catalyst) and Ni (impurity) in floor surface loadings, and with Co in passive deposition samples. Interpretation of elemental ratios (Co/Fe) assisted in distinguishing among CNT and non-CNT sources of contamination. Stable isotopes of Pb impurities were useful for identifying aerosolized CNTs in the workplace environment of a downstream user, as CNTs from different manufacturers each had distinctive Pb isotope signatures. Pb isotopes were not useful for identifying CNT releases within a CNT manufacturing environment, however, because the CNT signature reflected the indoor background signature. CNT manufacturing companies and downstream users of CNTs will benefit from the availability of alternative and complementary strategies for identifying the presence/absence of CNTs in the workplace and for monitoring the effectiveness of control measures.

The isotopic effects of 13C-labeled large carbon cage (C70) fullerenes and their formation process

¹³C-enriched large carbon cage-based fullerenes were synthesized on a large scale by an arc discharge method.

The isotope method for the determination of stoichiometry between compounds forming the polypyrrole and glucose oxidase composite

Stable isotope ratio mass spectrometry is a conventional method used in archaeology, and medical, environmental and paleoenvironmental reconstruction studies. However new insights and applicability of the equipment often open new research areas and improve our understanding of the ongoing processes. Therefore the stable isotope ratio mass spectrometry method was applied for the stoichiometry determination of the complex polypyrrole and glucose oxidase composite (PPy-GOx composite). The enzyme glucose oxidase and conducting polymer polypyrrole were reported to form a composite, which was evaluated in time using the dynamic light scattering method. The consistent enlargement of the PPy-GOx composite and the relative decrease of the spare enzyme molecules were observed in the polymerization solution. UV-VIS spectrometry was employed to follow the polymerization process. The isotope mixing model was applied for the evaluation of the constitution of the PPy-GOx composite. According to the obtained results the determination of the PPy-GOx composite stoichiometry could be more reliably determined using the nitrogen isotope ratio approach in comparison to the carbon approach. We expect that this novel work will widen the applications of stable isotope ratio mass spectrometry in research.

Stable isotope tracer to determine uptake and efflux dynamics of ZnO Nano- and bulk particles and dissolved Zn to an estuarine snail

Zinc oxide nanoparticles (ZnO NPs) are among the most commercialized engineered nanomaterials. Their biological impact in aquatic organisms has been associated with dissolution, but there is also evidence of nanospecific effects. In this study the waterborne uptake and efflux kinetics of isotopically labeled (68)ZnO NPs (7.8 ± 1.2 nm), in comparison to aqueous (68)Zn and (68)ZnO bulk particles (up to 2 μm), were determined for the estuarine snail Peringia ulvae following a 7 d exposure (nominally 20 μg (68)Zn L(-1)) and 28 d depuration. Detection of the (68)Zn label was achieved by high precision multiple-collector ICP-MS (MC-ICP-MS). Previous characterization in artificial estuarine water revealed that the NPs underwent initial aggregation and solubilized up to 60% within 1-2 days. Bulk and aqueous forms were significantly more bioavailable than (68)ZnO NPs (p < 0.05), but after correcting for dissolution, aqueous (0.074 L(-1) g(-1) d(-1)) and NP (0.070 L(-1) g(-1) d(-1)) uptake rate constants were highly comparable. The rate constant of loss for (68)Zn aqueous (0.012 ± 0.005 d(-1)) and (68)ZnO NPs (0.012 ± 0.007 d(-1)) were identical. These results strongly suggest that in this exposure scenario the bioaccumulation of Zn from ZnO NPs is primarily dependent upon solubility.

Engineered nanoparticles and their identification among natural nanoparticles

The more nanotechnology develops, the more likely the release of engineered nanoparticles into the environment becomes. Due to a huge excess of natural nanoparticles, the identification and quantification of engineered nanoparticles pose a big challenge to analysts. Moreover, identification in a qualitative sense and quantification by mass concentration alone are not sufficient, because the potential environmental hazard arising from engineered nanoparticles is controlled by many other properties of the particles. We discuss the most important methods of fractionation and detection of both natural and engineered nanoparticles, with a focus on the chemical nature of the particles, particle concentration, and particle size. Analyses should not rely on only one method; instead, several complementary methods should, if possible, be used. Coupled techniques should be further developed and increasingly applied. Dedicated techniques that are tailored to the search for a particular sort of engineered nanoparticles are more promising than universal approaches that search for any engineered nanoparticles.

Evaluation of stable isotope tracing for ZnO nanomaterials--new constraints from high precision isotope analyses and modeling

This contribution evaluates two possible routes of stable isotope tracing for ZnO nanomaterials. For this we carried out the first high precision Zn isotope analyses of commercially available ZnO nanomaterials, to investigate whether such materials exhibit isotope fractionations that can be exploited for tracing purposes. These measurements revealed Zn isotopic compositions (of δ(66/64)Zn = +0.28 to -0.31‰ relative to JMC Lyon Zn) that are indistinguishable from "normal" natural and anthropogenic Zn in environmental samples. Stable isotope tracing therefore requires the application of purpose-made isotopically enriched ZnO nanoparticles. A detailed evaluation identified the most suitable and cost-effective labeling isotopes for different analytical requirements and techniques. It is shown that, using relatively inexpensive (68)Zn for labeling, ZnO nanoparticles can be reliably detected in natural samples with a Zn background of 100 μg/g at concentrations as low as about 5 ng/g, if the isotopic tracing analyses are carried out by high precision mass spectrometry. Stable isotope tracing may also be able to differentiate between the uptake by organisms of particulate ZnO and Zn(2+) ions from the dissolution of nanoparticles.

Comparison of dermal absorption of zinc from different sunscreen formulations and differing UV exposure based on stable isotope tracing

In a pilot study to determine if zinc (Zn) from zinc oxide nanoparticles in sunscreen can penetrate human skin in vivo, nanoparticles (~30nm) of a stable isotope (52% (68)Zn enrichment) were incorporated into an essentially phytochemical-based formulation and applied to the backs of 3 human subjects twice daily for 5 days during the Southern Hemisphere winter. Blood and urine were collected prior to application and at regular intervals and up to 50 days. As observed in a larger outdoor trial following this pilot study but with a different formulation and with UV exposure: values of (68)Zn in blood continued to increase beyond the 5 day application phase with the highest measurement at 14 days after the first application; variable amounts of the (68)Zn tracer were observed in urine; and the amounts of extra Zn added to blood were small and indicate very low levels of absorption (minimal estimate <0.01% of the applied dose) through the skin. Reasons for differences in absorption detected in the stable isotope trials and previous investigations include: the sensitivity of the stable isotope method; the duration of the investigations; the number of applications of sunscreen formulation; in vitro methods with excised skin; lack of measurement of blood and urine; no skin flexing; and lack of UV exposure.

Isotopically modified nanoparticles for enhanced detection in bioaccumulation studies

This work presents results on synthesis of isotopically enriched (99% (65)Cu) copper oxide nanoparticles and its application in ecotoxicological studies. (65)CuO nanoparticles were synthesized as spheres (7 nm) and rods (7 × 40 nm). Significant differences were observed between the reactivity and dissolution of spherical and rod shaped nanoparticles. The extreme sensitivity of the stable isotope tracing technique developed in this study allowed determining Cu uptake at exposure concentrations equivalent to background Cu concentrations in freshwater systems (0.2-30 μg/L). Without a tracer, detection of newly accumulated Cu was impossible, even at exposure concentrations surpassing some of the most contaminated water systems (>1 mg/L).

Experimental considerations on the cytotoxicity of nanoparticles

Engineered nanoparticles are one of the leading nanomaterials currently under investigation due to their applicability in various fields, including drug and gene delivery, biosensors, cancer treatment and diagnostic tools. Moreover, the number of commercial products containing nanoparticles released on the market is rapidly increasing. Nanoparticles are already widely distributed in air, cosmetics, medicines and even in food. Therefore, the unintended adverse effect of nanoparticle exposure is a growing concern both academically and socially. In this context, the toxicity of nanoparticles has been extensively studied; however, several challenges are encountered due to the lack of standardized protocols. In order to improve the experimental conditions of nanoparticle toxicity studies, serious consideration is critical to obtain reliable and realistic data. The cell type must be selected considering the introduction route and target organ of the nanoparticle. In addition, the nanoparticle dose must reflect the realistic concentration of nanoparticles and must be loaded as a well-dispersed form to observe the accurate size- and shape-dependent effect. In deciding the cytotoxicity assay method, it is important to choose the appropriate method that could measure the toxicity of interest without the false-negative or -positive misinterpretation of the toxicity result.

Review: Do engineered nanoparticles pose a significant threat to the aquatic environment?

Nanotechnology is a rapidly growing industry of global economic importance, exploiting the novel characteristics of materials manufactured at the nanoscale. The properties of engineered nanoparticles (ENPs) that make them useful in a wide range of industrial applications, however, have led to concerns regarding their potential impact on human and environmental health. The aquatic environment is particularly at risk of exposure to ENPs, as it acts as a sink for most environmental contaminants. This paper critically evaluates what is currently known about sources and discharge of ENPs to the aquatic environment and how the physicochemical characteristics of ENPs affect their fate and behaviour and thus availability for uptake into aquatic organisms, and assesses reported toxicological effects. Having reviewed the ecotoxicological information, the conclusion is that whilst there are data indicating some nanoparticles have the potential to induce harm in exposed aquatic organisms, there is insufficient evidence for harm, for known/modelled environmental concentrations for almost all ENPs considered. This conclusion, however, must be balanced by the fact that there are significant gaps in our understanding on the fate and behaviour of ENPs in the aquatic environment. Greater confidence in the assessments on ENP impacts in aquatic systems to enable effective comparisons across studies urgently requires more standardised approaches for ENP hazard identification, and critically, more thorough characterisations on the exposed particles. There is also an urgent need for the advancement of tools and techniques that can accurately quantify and visualise uptake of nanoparticles into biological tissues.

Synthesis of isotopically modified ZnO nanoparticles and their potential as nanotoxicity tracers

Understanding the behavior of engineered nanoparticles in the environment and within organisms is perhaps the biggest obstacle to the safe development of nanotechnologies. Reliable tracing is a particular issue for nanoparticles such as ZnO, because Zn is an essential element and a common pollutant thus present at elevated background concentrations. We synthesized isotopically enriched (89.6%) with a rare isotope of Zn (67Zn) ZnO nanoparticles and measured the uptake of 67Zn by L. stagnalis exposed to diatoms amended with the particles. Stable isotope technique is sufficiently sensitive to determine the uptake of Zn at an exposure equivalent to lower concentration range (<15 μg g(-1)). Without a tracer, detection of newly accumulated Zn is significant at Zn exposure concentration only above 5000 μg g(-1) which represents some of the most contaminated Zn conditions. Only by using a tracer we can study Zn uptake at a range of environmentally realistic exposure conditions.

Strategies for quantifying C(60) fullerenes in environmental and biological samples and implications for studies in environmental health and ecotoxicology

Fullerenes are sphere-like molecules with unique physico-chemical properties, which render them of particular interest in biomedical research, consumer products and industrial applications. Human and environmental exposure to fullerenes is not a new phenomenon, due to a long history of hydrocarbon-combustion sources, and will only increase in the future, as incorporation of fullerenes into consumer products becomes more widespread for use as anti-aging, anti-bacterial or anti-apoptotic agents.An essential step in the determination of biological effects of fullerenes (and their surface-functionalized derivatives) is establishment of exposure-assessment techniques. However, in ecotoxicological studies, quantification of fullerenes is performed infrequently because robust, uniformly applicable analytical approaches have yet to be identified, due to the wide variety of sample types. Moreover, the unique physico-chemistry of fullerenes in aqueous matrices requires reassessment of conventional analytical approaches, especially in more complex biological matrices (e.g., urine, blood, plasma, milk, and tissue).Here, we present a review of current analytical approaches for the quantification of fullerenes and propose a consensus approach for determination of these nanomaterials in a variety of environmental and biological matrices.

What do we (need to) know about the kinetic properties of nanoparticles in the body?

Nowadays the development and applications of nanotechnology are of major importance in both industrial and consumer areas. However, the knowledge on human exposure and possible toxicity of nanotechnology products is limited. To understand the mechanism of toxicity, thorough knowledge of the toxicokinetic properties of nanoparticles is warranted. There is a need for information on the absorption, distribution, metabolism and excretion (ADME) of nanoparticles and validated detection methods of these man-made nanoparticles. Determination of the ADME properties of nanoparticles requires specialised detection methods in different biological matrices (e.g. blood and organs). In this paper, the current knowledge on the kinetic properties of nanoparticles is reviewed. Moreover, knowledge gaps from a kinetic point of view (detection, dose, ADME processes) are identified.

Particokinetics In Vitro: Dosimetry Considerations for In Vitro Nanoparticle Toxicity Assessments

The rapid growth in the use of in vitro methods for nanoparticle toxicity assessment has proceeded with limited consideration of the unique kinetics of these materials in solution. Particles in general and nanoparticles specifically, diffuse, settle, and agglomerate in cell culture media as a function of systemic and particle properties: media density and viscosity and particle size, shape, charge and density, for example. Cellular dose then is also a function of these factors as they determine the rate of transport of nanoparticles to cells in culture. Here we develop and apply the principles of dosimetry in vitro and outline an approach for simulation of nanoparticle particokinetics in cell culture systems. We illustrate that where equal mass concentrations (mug/ml) imply equal doses for dissimilar materials, the corresponding particle number or surface area concentration doses differ by orders of magnitude. More importantly, when rates of diffusional and gravitational particle delivery are accounted for, trends and magnitude of the cellular dose as a function of particle size and density differ significantly from those implied by "concentration" doses. For example, 15-nm silver nanoparticles appear approximately 4000 times more potent than micron-sized cadmium oxide particles on a cm(2)/ml media basis, but are only approximately 50 times more potent when differences in delivery to adherent cells are considered. We conclude that simple surrogates of dose can cause significant misinterpretation of response and uptake data for nanoparticles in vitro. Incorporating particokinetics and principles of dosimetry would significantly improve the basis for nanoparticle toxicity assessment, increasing the predictive power and scalability of such assays.