Graphene-based materials have been explored for innovative technological applications in electronic devices, high-performance plastics, and biotechnology.
A discovery by researchers from CNPEM (Brazilian Center for Research in Energy and Materials) reveals that the interaction of nanomaterials with proteins and biomolecules from bacteria can alter the behavior and toxicity of nanomaterials, such as graphene oxide.
The study, conducted by Francine Côa during her doctoral research, under the guidance of CNPEM researcher Diego Martinez, investigated how biomolecules from the bacterium E. coli interact with graphene oxide and modify its toxicological effects on the model organism C. elegans (a nematode isolated from soils).
Graphene oxide is an advanced material that has been widely explored for technological and industrial applications; such as fast-charging batteries and heat sinks for smartphones, in the reinforcement of metal alloys, catalysts, special packaging and plastics for the automotive and aerospace industries, in the development of sensors and biosensors, and even in sporting goods, water purification, and new medicines. The growing and diverse range of applications of graphene oxide reinforces the importance of understanding its behavior and its biological and environmental effects in a proactive and responsible way.
The choice of E. coli is directly related to the experimental model under study: this bacterium is used as food for C. elegans. During digestion, bacterial cells are ruptured and release biomolecules that can interact with nanomaterials present in the body. The research investigated whether these biomolecules would be capable of forming a layer on graphene oxide, the so-called “ecocorona”, and, therefore, modifying its toxicity and biodistribution.
The results showed that this interaction can produce distinct effects. When coated with E. coli ecocorona, graphene oxide showed lower toxicity compared to when evaluated in isolation. However, when the coated (coronated) material was combined with metal ions (silver), the effect was the opposite, with increased toxicity and metal accumulation in organisms.
“E. coli is used as food by C. elegans, so we sought to understand if the biomolecules from the bacteria during digestion could interact with graphene oxide and modify its toxicity. We observed that the formation of ecocorona reduces the toxic effects of the isolated material, but in the presence of metal, the effect was the opposite, with a significant increase in toxicity and metal accumulation”, explains Francine Côa, who currently works in the area of product safety in the pharmaceutical industry.
For the researchers, these results reinforce the idea that evaluating the safety of a nanomaterial only in its “pure” form may not be sufficient to determine its impacts and risks. In biological and environmental systems, these nanomaterials come into contact with bacteria, proteins, salts, metals, and other substances that can significantly alter their behavior and effects. For researchers, understanding these “nanobio” interactions is fundamental to accelerating innovation and developing increasingly safe and sustainable products.
“Our results reinforce the importance of developing laboratory studies integrated with more realistic exposure scenarios. Nanomaterials do not remain unchanged after being released into the environment: they undergo transformations and interact with different chemical and biological components, and these interactions must be considered when evaluating their benefits and risks”, explains Diego Martinez, CNPEM researcher and the research advisor.
The results of the CNPEM research were published in September in the journal Nanoscale Advances. To understand the phenomenon, the researchers produced an ecocorona from biomolecules extracted from E. coli and observed how they modify the characteristics of graphene oxide. Physicochemical analyses revealed alterations in the topography, roughness, thickness, chemical composition, and stability of the material in suspension. Proteomic analysis identified over a thousand different proteins attached to the material’s surface, demonstrating that the formation of the ecocorona is highly complex and dynamic.
“Trojan Horse” effect
The most surprising discovery occurred when the researchers combined graphene oxide with silver ions. Analyses showed that the formation of the ecocorona significantly increased the capacity of graphene oxide to associate with silver. This result, combined with the
greater accumulation of the metal observed in the organisms, helps explain the “Trojan Horse” effect identified in the study.
The effects were observed in different parts of C. elegans. The combination caused intestinal, neuronal, and reproductive changes. It was also the treatment that caused the greatest destruction of the nematode’s reproductive cells, even at lower silver concentrations.
In addition to the observed effects, the study has implications for the safety assessment of nanomaterials itself. As E. coli is routinely used as food in assays with C. elegans, disregarding its interaction with the tested materials may influence the interpretation of the results. The findings reinforce the importance of considering these interactions in the design and interpretation of nanotoxicology studies, contributing to more robust assessments during the development of protocols, technical standards, and regulatory aspects.
This study was conducted by CNPEM in collaboration with the Center for Nuclear Energy in Agriculture at the University of São Paulo and the group of Environmental Nanoscience at the University of Birmingham in the United Kingdom, with financial support from CAPES, CNPq and FAPESP
About CNPEM
The Brazilian Center for Research in Energy and Materials (CNPEM) is home to a state-of-the-art, multi-user and multidisciplinary scientific environment and works on different fronts within the Brazilian National System for Science, Technology and Innovation. A social organization overseen by the Ministry of Science, Technology and Innovation (MCTI), with the involvement of the Ministry of Education and the Ministry of Health, CNPEM is driven by research that impacts the areas of health, energy, renewable materials, and sustainability. It is responsible for Sirius, the largest assembly of scientific equipment constructed in the country, and is currently constructing Project Orion, a laboratory complex for advanced pathogen research. Highly specialized science and engineering teams, sophisticated infrastructure open to the scientific community, strategic lines of investigation, innovative projects involving the productive sector, and training for researchers and students are the pillars of this institution that is unique in Brazil and able to serve as a bridge between knowledge and innovation. CNPEM’s research and development activities are carried out through its four National Laboratories: Synchrotron Light (LNLS), Biosciences (LNBio), Nanotechnology (LNNano), Biorenewables (LNBR), as well as its Technology Unit (DAT) and the Ilum School of Science — an undergraduate program in Science and Technology.
