Subchronic exposure to palladium nanoparticles affects serum levels of cytokines in female Wistar rats

The effect of airborne Palladium nanoparticles on human lung cells, endothelium and blood - A combinatory approach using three in vitro models

A better understanding of the mechanisms behind adverse health effects caused by airborne fine particles and nanoparticles (NP) is essential to improve risk assessment and identification the most critical particle exposures. While the use of automobile catalytic converters is decreasing the exhausts of harmful gases, concentrations of fine airborne particles and nanoparticles (NPs) from catalytic metals such as Palladium (Pd) are reaching their upper safe level. Here we used a combinatory approach with three in vitro model systems to study the toxicity of Pd particles, to infer their potential effects on human health upon inhalation. The three model systems are 1) a lung system with human lung cells (ALI), 2) an endothelial cell system and 3) a human whole blood loop system. All three model systems were exposed to the exact same type of Pd NPs. The ALI lung cell exposure system showed a clear reduction in cell growth from 24 h onwards and the effect persisted over a longer period of time. In the endothelial cell model, Pd NPs induced apoptosis, but not to the same extent as the most aggressive types of NPs such as TiO₂. Similarly, Pd triggered clear coagulation and contact system activation but not as forcefully as the highly thrombogenic TiO₂ NPs. In summary, we show that our 3-step in vitro model of the human lung and surrounding vessels can be a useful tool for studying pathological events triggered by airborne fine particles and NPs.

Potential Environmental and Health Implications from the Scaled-Up Production and Disposal of Nanomaterials Used in Biosensors

Biosensors often combine biological recognition elements with nanomaterials of varying compositions and dimensions to facilitate or enhance the operating mechanism of the device. While incorporating nanomaterials is beneficial to developing high-performance biosensors, at the stages of scale-up and disposal, it may lead to the unmanaged release of toxic nanomaterials. Here we attempt to foster connections between the domains of biosensors development and human and environmental toxicology to encourage a holistic approach to the development and scale-up of biosensors. We begin by exploring the toxicity of nanomaterials commonly used in biosensor design. From our analysis, we introduce five factors with a role in nanotoxicity that should be considered at the biosensor development stages to better manage toxicity. Finally, we contextualize the discussion by presenting the relevant stages and routes of exposure in the biosensor life cycle. Our review found little consensus on how the factors presented govern nanomaterial toxicity, especially in composite and alloyed nanomaterials. To bridge the current gap in understanding and mitigate the risks of uncontrolled nanomaterial release, we advocate for greater collaboration through a precautionary One Health approach to future development and a movement towards a circular approach to biosensor use and disposal.

Palladium nanoparticles as emerging pollutants from motor vehicles: An in-depth review on distribution, uptake and toxicological effects in occupational and living environment

Palladium nanoparticles (PdNPs) play an integral role in motor vehicles as the primary vehicle exhaust catalyst (VEC) for tackling environmental pollution. Automobiles equipped with Pd-based catalytic converters were introduced in the mid-1970s and ever since the demand for Pd has steadily increased due to stringent emission standards imposed in many developed and developing countries. However, at the same time, the increasing usage of Pd in VECs has led to the release of nano-sized Pd particles in the environment, thus, emerging as a new source of environmental pollution. The present reports in the literature have shown gradual increasing levels of Pd particles in different urban environmental compartments and internalization of Pd particles in living organisms such as plants, aquatic species and animals. Occupational workers and the general population living in urban areas and near major highways are the most vulnerable as they may be chronically exposed to PdNPs. Risk assessment studies have shown acute and chronic toxicity exerted by PdNPs in both in-vitro and in-vivo models but the underlying mechanism of PdNPs toxicity is still not fully understood. The review intends to provide readers with an in-depth account on the demand and supply of Pd, global distribution of PdNPs in various environmental matrices, their migration and uptake by living species and lastly, their health risks, so as to serve as a useful reference to facilitate further research and development for safe and sustainable technology.

Ex vivo exposure to different types of graphene-based nanomaterials consistently alters human blood secretome

The biomedical applications of graphene-based nanomaterials (GBN) have significantly grown in the last years. Many of these applications suppose their intravenous exposure and, in this way, GBN could encounter blood cells triggering an immunological response of unknown effects. Consequently, understanding the relationships between GBN and the immune system response should be a prerequisite for its adequate use in biomedicine. In the present study, we have conducted a little explored ex vivo exposure method in order to study the complexity of the secretome given by the interactions between GBN and blood cells. Blood samples from different healthy donors were exposed to three different types of GBN widely used in the biomedical field. In this sense, graphene oxide (GO), graphene nanoplatelets (GNPs), graphene nanoribbons (GNRs) and a panel of 105 proteins representatives of the blood secretome were evaluated. The results show broad changes in both the cytokines number and the expression levels, with important changes in inflammatory response markers. Furthermore, the indirect soft-agar assay was used as a tool to unravel the global functional impact of the found secretome changes. Our results indicate that the GBN-induced altered secretome can modify the natural anchorage-independent growth capacity of HeLa cells, used as a model. As a conclusion, this study describes an innovative approach to study the potential harmful effects of GBN, providing relevant data to be considered in the biomedical context when GBN are planned to be used in patients.

Bio-engineered palladium nanoparticles: model for risk assessment study of automotive particulate pollution on macrophage cell lines

The surge in vehicular activity in densely populated areas has led to an increased concentration of airborne palladium nanoparticles (PdNPs) in the environment. Recent toxicity data have indicated that PdNPs exhibit adverse effects in in vitro and in vivo models, however, their effect on the immune system is not fully understood. Therefore, in the present study, we aimed to evaluate possible toxic effects of bio-engineered palladium nanoparticles on the murine macrophage cell line (J774). Here we prepared palladium nanoparticles using aqueous leaf extract of Parthenium hysterophorus and characterized them by UV-Vis spectroscopy, XRD, FT-IR spectroscopy, HR-TEM, EDX, SEM and zeta potential. Toxicity parameters such as cell viability, cell membrane integrity, induction of apoptosis and ROS production were assessed on J774 cell lines. Spherical palladium nanoparticles of mean size ∼4 nm, when subjected to time and dose-dependent cytotoxicity assay, showed cell viability was >95% at lower doses (25, 200 μg mL-1) and <50% at higher doses of palladium nanoparticles (400, 500 μg mL-1) after 24 hours of incubation. We also observed cell membrane injury at higher doses by lactate dehydrogenase assay. The induction of apoptosis observed was moderate. H2DCFDA assay revealed visible cell damage which could be due to modest levels of ROS generation. The detection of Pd in the road-dust samples of New Delhi using inductively coupled plasma-mass spectroscopy (ICP-MS) technique was also investigated.

An Up-To-Date Review on Biomedical Applications of Palladium Nanoparticles

Palladium nanoparticles (PdNPs) have intrinsic features, such as brilliant catalytic, electronic, physical, mechanical, and optical properties, as well as diversity in shape and size. The initial researches proved that PdNPs have impressive potential for the development of novel photothermal agents, photoacoustic agents, antimicrobial/antitumor agents, gene/drug carriers, prodrug activators, and biosensors. However, very few studies have taken the benefit of the unique characteristics of PdNPs for applications in the biomedical field in comparison with other metals like gold, silver, or iron. Thus, this review aims to highlight the potential applications in the biomedical field of PdNPs. From that, the review provides the perceptual vision for the future development of PdNPs in this field.

Sub-chronic palladium nanoparticle effects on the endocrine reproductive system of female Wistar rats: Preliminary data

The technologically interesting properties of palladium nanoparticles (Pd-NPs) allowed their widespread industrial application, although concerns emerged on increasing general and occupational levels of exposure. In this context, to assess the toxicological behavior of Pd-NPs, and particularly their endocrine disruptive potential, has become a public health priority. Therefore, we evaluated Pd-NP impact on the female endocrine reproductive system of Wistar rats sub-chronically treated for 90 days with increasing doses of this xenobiotic (0.12, 1.2, and 12 µg/kg, administered at days 1, 30, and 60 for cumulative doses of 0.36, 3.6, and 36 µg/kg) via the intravenous route. In this regard, we investigated potential alterations in different sex hormone, for example, estradiol, follicle-stimulating hormone (FSH), luteinizing hormone, progesterone, and testosterone, serum concentrations. All treated groups showed significantly greater levels of FSH compared to controls, suggesting a possible impact of Pd-NPs on the regulatory system that controls the normal physiology of female reproductive function. Although relevant, since obtained under sub-chronic, low-dose conditions of exposure resembling those encountered in real-world scenarios, the present results are preliminary and require confirmation as well as identification of the possible underlining molecular mechanisms. From a public and occupational health perspective, implications for the reproductive health of exposed subjects and the next generations of women exposed during their childbearing age or pregnancy should be elucidated. This information is essential to elaborate adequate preventive strategies for assessing and controlling possible Pd-NPs adverse effects on the endocrine system.

Novel Nanoparticulate and Ionic Titanium Antigens for Hypersensitivity Testing

Titanium is used in a wide variety of materials ranging from medical devices to materials used in everyday life. Adverse biological reactions that could occur in patients, consumers, and workers should be monitored and prevented. There is a lack of available agents to test and predict titanium-related hypersensitivity. The aim of this study was to develop two bioavailable titanium substances in ionic and nanoparticulate form to serve as antigens for hypersensitivity testing in vitro. Peripheral blood mononuclear cells from 20 test subjects were stimulated with the antigens and secretion of monocytic and lymphatic cytokines and chemokines were measured by a multiplex bead assay. Lymphocyte stimulation indices were also determined in a subset of test subjects by measuring CD69 and HLA-DR expression by flow cytometry. Cytokine profiling revealed that both antigens increased production of typical monocyte and macrophage secreted cytokines after 24 h, with significant increases in IL-1β, IL-7, IL-10, IL-12, IL-2R, IL-6, GM-CSF, TNF-α, IL-1RA, MIP-1α, MIP-1β, IFN-α, and IL-15. Lymphatic cytokines and chemokines were not significantly induced by activation. After seven days of stimulation, ionic-Ti (2.5 μg/mL) caused proliferation (stimulation index > 2) of CD4+ cells and CD8+ cells in all persons tested (N = 6), while titanium dioxide nanoparticles (50 μg/mL) only caused significant proliferation of CD4+ cells. Our preliminary results show that the experimental titanium antigens, especially the ionic form, induce a general inflammatory response in vitro. A relevant cohort of test subjects is required to further elucidate their potential for predictive hypersensitivity testing.

Palladium Nanoparticles: Toxicological Effects and Potential Implications for Occupational Risk Assessment

The increasing technological applications of palladium nanoparticles (Pd-NPs) and their consequent enhancing release into the community and occupational environments, have raised public health concerns regarding possible adverse effects for exposed subjects, and particularly for workers chronically and highly exposed to these materials, whose toxico-kinetic and dynamic behavior remains to be fully understood. Therefore, this review aimed to critically analyze literature data to achieve a more comprehensive knowledge on the toxicological profile of Pd-NPs. Results from available studies demonstrated the potential for these chemicals to affect the ecosystem function, to exert cytotoxic and pro-inflammatory effects in vitro as well as to induce early alterations in different target organs in in vivo models. However, our revision pointed out the need for future studies aimed to clarify the role of the NP physico-chemical properties in determining their toxicological behavior, as well as the importance to carry out investigations focused on environmental and biological monitoring to verify and validate experimental biomarkers of exposure and early effect in real exposure contexts. Overall, this may be helpful to support the definition of suitable strategies for the assessment, communication and management of Pd-NP occupational risks to protect the health and safety of workers.