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1. Advances and challenges in the ecological risk assessment of engineered nanomaterials in aquatic ecosystems: A review

   https://doi.org/10.1016/j.scitotenv.2025.180739  

   Keller, Arturo A; Slaveykova, Vera I (November 2025, Science of The Total Environment)

   Generating appropriate ecological risk assessments to support the rapid growth of nanotechnology requires a comprehensive understanding of the potential effects of engineered nanomaterials (ENMs), both toxic and beneficial, and accurate predictions of their environmental concentrations. While significant data exists for widely used nanomaterials, there remains a critical knowledge gap regarding the environmental and biological impacts of emerging ENMs, including graphene oxide, nanodiamonds, carbon nanotubes, and less common metal and metal oxides. This review aims to synthesize current knowledge on the ecological risks of emerging ENMs in aquatic environments. The concentrations are likely to be below common toxicological endpoints. In addition, for some of them there is the potential for hormesis: a beneficial dose that promotes growth of the organisms. Novel approaches, such as the “omics,” can elucidate these effects. The review identifies key knowledge gaps, such as the necessity for better information on the effects of nanomaterial mixtures and the potential effects of organisms on the fate of ENMs, as well as for better models for estimating biomagnification. While the integration of artificial intelligence will serve to close these knowledge gaps, more standardized toxicity testing protocols are required to expand the number of studies that can be used to train machine learning models. 

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

   https://doi.org/10.3390/bios12121082  

   McCourt, Kelli M.; Cochran, Jarad; Abdelbasir, Sabah M.; Carraway, Elizabeth R.; Tzeng, Tzuen-Rong J.; Tsyusko, Olga V.; Vanegas, Diana C. (December 2022, 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. 

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3. Chronic exposure to complex metal oxide nanoparticles elicits rapid resistance in Shewanella oneidensis MR-1

   https://doi.org/10.1039/C9SC01942A  

   Mitchell, Stephanie L.; Hudson-Smith, Natalie V.; Cahill, Meghan S.; Reynolds, Benjamin N.; Frand, Seth D.; Green, Curtis M.; Wang, Chenyu; Hang, Mimi N.; Hernandez, Rodrigo Tapia; Hamers, Robert J.; et al (January 2019, Chemical Science)

   Engineered nanoparticles are incorporated into numerous emerging technologies because of their unique physical and chemical properties. Many of these properties facilitate novel interactions, including both intentional and accidental effects on biological systems. Silver-containing particles are widely used as antimicrobial agents and recent evidence indicates that bacteria rapidly become resistant to these nanoparticles. Much less studied is the chronic exposure of bacteria to particles that were not designed to interact with microorganisms. For example, previous work has demonstrated that the lithium intercalated battery cathode nanosheet, nickel manganese cobalt oxide (NMC), is cytotoxic and causes a significant delay in growth of Shewanella oneidensis MR-1 upon acute exposure. Here, we report that S. oneidensis MR-1 rapidly adapts to chronic NMC exposure and is subsequently able to survive in much higher concentrations of these particles, providing the first evidence of permanent bacterial resistance following exposure to nanoparticles that were not intended as antibacterial agents. We also found that when NMC-adapted bacteria were subjected to only the metal ions released from this material, their specific growth rates were higher than when exposed to the nanoparticle. As such, we provide here the first demonstration of bacterial resistance to complex metal oxide nanoparticles with an adaptation mechanism that cannot be fully explained by multi-metal adaptation. Importantly, this adaptation persists even after the organism has been grown in pristine media for multiple generations, indicating that S. oneidensis MR-1 has developed permanent resistance to NMC. 

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4. Cobalt and nickel ion synergy promotes gene amplification and stable metal resistance in Shewanella oneidensis

   https://doi.org/10.1128/aem.01844-25  

   Gavin, Alessandra G; Mitchell, Stephanie L; Carlson, Erin E (July 2026, Applied and Environmental Microbiology)

   Bose, Arpita (Ed.)

   ABSTRACT Microbial species are integral in environmental homeostasis and have thus developed diverse strategies to adapt, survive, and proliferate under exogenous stress. The growing demand for nanoscale battery materials has led to increasing environmental concentrations of nanomaterials and their constituent metal ions. Previous work has shown that the Gram-negative bacteriumShewanella oneidensisis able to rapidly evolve resistance to one such nanomaterial, lithiated nickel manganese cobalt oxide (NMC). Yet, the specific stimuli that trigger resistance evolution and the ensuing genomic changes were previously unknown. Here, we demonstrate that the combination of cobalt and nickel ions released from NMC trigger a gene amplification event that enables stable nanomaterial and metal resistance, likely caused by amplification of a cation efflux pump. Amplification copy number is highly dynamic over the period of study, yet amplification events persist over prolonged recovery in the absence of metal stress. Growth rate comparisons reveal no physiological cost associated with a high copy number. The stability of this genomic mutation combined with the lack of observable fitness cost distinguishes this genomic perturbation from previously reported gene amplification events. Finally, the observed amplification event was unique to the combination of cobalt and nickel, which implies that the intracellular targets of these metal ions have a specific interaction that yield resistance. Ultimately, we report a dynamic and specific gene amplification event that allowsS. oneidensisto survive metal stress. This work not only illuminates the broader ecological consequences associated with introducing nanomaterials and metals into the environment but also provides insight into the larger scope of bacterial resistance mechanisms. IMPORTANCEStudying mechanisms of microbial resistance evolution is critical for understanding the role of bacteria in the environment and developing new strategies to combat antimicrobial resistance to modern therapeutics. Technological innovation has often led to the introduction of novel environmental stressors that impart pressure on microbes to evolve resistance. This may ultimately lead to novel resistance genes or gene cassettes in the environmental gene pool, which could further promote antimicrobial resistance in pathogenic organisms. In this study, we highlight the importance of considering gene amplification as a mechanism of bacterial resistance to environmental toxins. We demonstrate that amplification events can exist within a population in the absence of selection pressure and without a clear fitness cost. Identifying specific stimuli that trigger these events will help us understand factors that accelerate bacterial resistance evolution and have the potential to disrupt ecosystem balance. 

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5. Cannabis sativa CBD Extract Exhibits Synergy with Broad-Spectrum Antibiotics against Salmonella enterica subsp. Enterica serovar typhimurium

   https://doi.org/10.3390/microorganisms10122360  

   Gildea, Logan; Ayariga, Joseph Atia; Xu, Junhuan; Villafane, Robert; Robertson, Boakai K.; Samuel-Foo, Michelle; Ajayi, Olufemi S. (December 2022, Microorganisms)

   New generation antibiotics are needed to combat the development of resistance to antimicrobials. One of the most promising new classes of antibiotics is cannabidiol (CBD). It is a non-toxic and low-resistance chemical that can be used to treat bacterial infections. The antibacterial activity of Cannabis sativa L. byproducts, specifically CBD, has been of growing interest in the field of novel therapeutics. As research continues to define and characterize the antibacterial activity that CBD possesses against a wide variety of bacterial species, it is important to examine potential interactions between CBD and common therapeutics such as broad-spectrum antibiotics. In this study it is demonstrated that CBD-antibiotic (combination of CBD and antibiotic) co-therapy can effectively fight Salmonella typhimurium (S. typhimurium) via membrane integrity disruption. This research serves to examine the potential synergy between CBD and three broad-spectrum antibiotics (ampicillin, kanamycin, and polymyxin B) for potential CBD-antibiotic co-therapy. In this study, it is revealed that S. typhimurium growth is inhibited at very low dosages of CBD-antibiotic. This interesting finding demonstrates that CBD and CBD-antibiotic co-therapies are viable novel alternatives to combating S. typhimurium. 

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