Transformation Of Nanomaterials Research Articles

Investigation into the trophic transfer and acute toxicity of phosphorus-based nano-agromaterials in Caenorhabditis elegans

Biogenic phosphorus (P) based – nanomaterials (NMs) are currently being explored as nanofertilizers. In this study, the acute toxic effects and trophic transfer of multiple types of P-based NMs were examined on soil-dwelling nematode, Caenorhabditis elegans. The study involved four variants of nanohydroxyapatites (nHAPs) synthesized either via a biogenic or a chemical route and another NM, nanophosphorus (nP), biosynthesized from bulk rock phosphate (RP). The pristine NMs differed in their physicochemical properties with each possessing different shapes (biogenic nHAP: platelet-shaped, ˜35 nm; biogenic nP, ˜5–10 nm: dots; chemically synthesized nHAPs: spherical, ˜33 nm, rod, ˜80 nm and needle-shaped, ˜64 nm). The toxic effects of NMs' in C. elegans were assessed using survival, hatching and reproductive cycle as the key endpoints in comparison to bulk controls, calcium phosphate and RP. The interactions and potential uptake of fluorescent-tagged nHAP to E. coli OP50 and C. elegans were investigated using confocal microscopy. The transformation of NMs within the nematode gut was also explored using dynamic light scattering and electron microscopy. C. elegans exposed to all of the variants of nHAP and the nP had 88–100% survival and 82–100% hatch rates and insignificant effects on brood size as observed at the tested environmentally relevant concentrations ranging from 5 to 100 μg.mL−1. Confocal microscopy confirmed the interaction and binding of fluorescent-tagged nHAP with the surface of E. coli OP50 and their trophic transfer and internalization into C. elegans. Interestingly, there was only a small reduction in the hydrodynamic diameter of the nHAP after their uptake into C. elegans and the transformed NMs did not induce any additional toxicity as evident by healthy brood sizes after 72 h. This study provides key information about the environmental safety of agriculturally relevant P-based NMs on non-target species.

Recent advances in nanomaterials for water protection and monitoring.

The efficient handling of wastewater pollutants is a must, since they are continuously defiling limited fresh water resources, seriously affecting the terrestrial, aquatic, and aerial flora and fauna. Our vision is to undertake an exhaustive examination of current research trends with a focus on nanomaterials (NMs) to considerably improve the performance of classical wastewater treatment technologies, e.g. adsorption, catalysis, separation, and disinfection. Additionally, NM-based sensor technologies are considered, since they have been significantly used for monitoring water contaminants. We also suggest future directions to inform investigators of potentially disruptive NM technologies that have to be investigated in more detail. The fate and environmental transformations of NMs, which need to be addressed before large-scale implementation of NMs for water purification, are also highlighted.

Aquatic toxicity of manufactured nanomaterials: challenges and recommendations for future toxicity testing

Environmental context The increased use of nanomaterials in industrial and consumer products requires robust strategies to identify risks when they are released into the environment. Aquatic toxicologists are beginning to possess a clearer understanding of the chemical and physical properties of nanomaterials in solution, and which of the properties potentially affect the health of aquatic organisms. This review highlights the main challenges encountered in aquatic nanotoxicity testing, provides recommendations for overcoming these challenges, and discusses recent studies that have advanced our understanding of the toxicity of three important OECD nanomaterials, titanium dioxide, zinc oxide and silver nanomaterials. Abstract Aquatic nanotoxicologists and ecotoxicologists have begun to identify the unique properties of the nanomaterials (NMs) that potentially affect the health of wildlife. In this review the scientific aims are to discuss the main challenges nanotoxicologists currently face in aquatic toxicity testing, including the transformations of NMs in aquatic test media (dissolution, aggregation and small molecule interactions), and modes of NM interference (optical interference, adsorption to assay components and generation of reactive oxygen species) on common toxicity assays. Three of the major OECD (Organisation for Economic Co-operation and Development) priority materials, titanium dioxide (TiO2), zinc oxide (ZnO) and silver (Ag) NMs, studied recently by the Natural Sciences and Engineering Research Council of Canada (NSERC), National Research Council of Canada (NRC) and the Business Development Bank of Canada (BDC) Nanotechnology Initiative (NNBNI), a Canadian consortium, have been identified to cause both bulk effect, dissolution-based (i.e. free metal), or NM-specific toxicity in aquatic organisms. TiO2 NMs are most toxic to algae, with toxicity being NM size-dependent and principally associated with binding of the materials to the organism. Conversely, dissolution of Zn and Ag NMs and the subsequent release of their ionic metal counterparts appear to represent the primary mode of toxicity to aquatic organisms for these NMs. In recent years, our understanding of the toxicological properties of these specific OECD relevant materials has increased significantly. Specifically, researchers have begun to alter their experimental design to identify the different behaviour of these materials as colloids and, by introducing appropriate controls and NM characterisation, aquatic nanotoxicologists are now beginning to possess a clearer understanding of the chemical and physical properties of these materials in solution, and how these materials may interact with organisms. Arming nanotoxicologists with this understanding, combined with knowledge of the physics, chemistry and biology of these materials is essential for maintaining the accuracy of all future toxicological assessments.

Monitoring migration and transformation of nanomaterials in polymeric composites during accelerated aging

The incorporation of small amounts of nanoadditives in polymeric compounds can introduce new mechanical, physical, electrical, magnetic, thermal and/or optical properties. The properties of these advanced materials have enabled new applications in several industrial sectors (electronics, automotive, textile...). In particular, for the nanomaterials (NM) described in this work, multi-walled carbon nanotubes (MWCNT) and silicon dioxide nanoparticles (SiO2 NP), the following properties have been described: MWCNT act as nucleating agents in thermoplastics, and change viscosity, affecting dispersion, orientation, and therefore mechanical, thermal, and electrical properties; and SiO2 NP act as flame retardant and display improved electrical and mechanical properties.The work described here is focused on the evaluation of the migration and transformation of NM included in polymer nanocomposites (NC) during accelerated climatic ageing. To this aim, we generated polyamide 6 (PA6) NC with different degree of compatibility between the NM and the polymeric matrix. These NC were submitted to accelerated aging conditions to simulate outdoor conditions (simulation of the use phase of the polymeric NC). The NC contain as nanofillers MWCNT and SiO2 NP with different surface properties to influence the compatibility with the polymeric matrix. The generated NC were evaluated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) with Energy-dispersive X-ray spectroscopy (EDX), thermogravimetry (TGA) and differential scanning calorimetry (DSC) before and after the aging process, to monitor the compatibility of the NM with the matrix: dispersion within the matrix, migration during aging, and modification of the polymer properties.The dispersion of SiO2 NP in the NC depended on their compatibility with the matrix. However, independently of their compatibility with the matrix, SiO2 NP were aggregated at the end of the accelerated aging process. In addition, degradation of the matrix and migration of nanoparticles to the surface was observed as well in the different types of SiO2 NP aged NC. Oppositely, compatibilized MWCNT (MWCNTMB) decreased the degradation of the polymer. Nevertheless, the nanomaterial migrated likewise to the surface during the ageing process.In order to evaluate the possible changes in the structure of nanomaterials due to the aging process, NM were extracted from the polymer by calcination. The nanomaterials extracted were analyzed by TGA, Fourier transform infrared spectroscopy (FT-IR), BET and TEM and its properties compared with calcinated raw NM. SiO2 hydrophilic nanoparticles were not affected by the aging process. However, both types of MWCNT were affected by the aging of the NC.