Gerardo Pulido-Reyes

An efficient method was developed to produce secondary nanoplastics and oligomers, mimicking environmental conditions. The produced materials caused physiological changes in the microalga C. reinhardtii at environmentally relevant concentrations.

Graphene-based conductive inks offer attractive possibilities in many printing technology applications. Often, these inks contain a mixture of compounds, such as solvents and stabilizers. For the safe(r) and sustainable use of such materials in products, potentially hazardous components must be identified and considered in the design stage. In this study, the hazards of few-layer graphene (FLG)-based ink formulations were tested in fish using in vitro (RTL-W1 cell line) and in vivo aquatic ecotoxicity tests (OECD TG 203). Five ink formulations were produced using different processing steps, containing varying amounts of solvents and stabilizers, with the end products formulated either in aqueous solutions or in powder form. The FLG ink formulations with the highest contents of the stabilizer sodium deoxycholate showed greater in vitro cytotoxic effects, but they did not provoke mortality in juvenile rainbow trout. However, exposure led to increased activities of the cytochrome P450 1a (Cyp1a) and Cyp3a enzymes in the liver, which play an essential role in the detoxification of xenobiotics, suggesting that any effects will be enhanced by the presence of the stabilizers. These results highlight the importance of an SSbD approach together with the use of appropriate testing tools and strategies. By incorporating additional processing steps to remove identified cytotoxic residual solvents and stabilizers, the hazard profile of the FLG inks improved, demonstrating that, by following the principles of the European Commission’s safe(r) and sustainable by design (SSbD) framework, one can contribute to the safe(r) and sustainable use of functional and advanced 2D materials in products.

The amount of plastics produced per year is in constant growth alongside their use in different sectors like the textile industry, agriculture or, more recently, in nanotechnology. Under certain environmental conditions, plastics break down into smaller pieces. Those plastics in the nanosize range are the most difficult to identify, quantify and remove and therefore probably prevail in aquatic ecosystems. Likewise, nanomaterial production has been increasing exponentially and therefore their potential release to the environment poses a threat. There is a lack of knowledge regarding the combined effects of co-occurring nanopolymers on biota. In this work, we have studied the individual toxicity of polystyrene nanoplastics (PS-NPs) as well as their combined effect with generation 7 PAMAM dendrimers (G7) on the filamentous cyanobacterium Anabaena sp. PCC7120, a relevant aquatic primary producer. Exposure to PS-NPs induced the overproduction of reactive oxygen species, lipid peroxidation, membrane disruptions, intracellular acidification and a decrease in photosynthetic activity. Internalization of the nanoplastics was also observed. Combined exposure to PS-NPs and G7 lowered PS-NP toxicity and precluded their internalization. This antagonistic interaction was due to the formation of heteroaggregates. Molecular biomarkers (differentially expressed proteins, DEPs) of the toxic effect of nanoplastics, G7 and their binary mixture were identified for the first time. These molecular biomarkers may be envisaged as a molecular signature of the toxic effect of the nanopolymers and could be predictors of cellular damage caused by exposure to nanopolymers.

The capping of the nanoparticles plays a vital role in their interaction with algal cells as the toxicological mechanism of polyvinylpyrrolidone-CeO₂NPs is different from uncoated CeO₂NPs.

Over the last five decades, plastics production has increased as a consequence of their use in strategic sectors causing damage on aquatic ecosystems.