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1. Nanoscale Interactions: Evaluating the Ecotoxicity of Engineered Nanoparticles on the Dynamics of Commercially Important Microalgal Strains

   Louime, Clifford J.; Diaz-Vazquez, Liz M.; Perez, Abner; Torres-Díaz, Marielys; Rojas-Perez, Arnulfo; Vázquez-López, Juan C.; Davilla Aguer, Catalina; Malca Reyes, Carlos A. (April 2020, International journal of science and engineering investigations)

   Society has long been exposed to naturally-occurring nanoparticles. Due to their ubiquitous nature, biological systems have adapted and built protection against their potential effects. However, for the past decades, there have been onslaughts of newly engineered nanoparticles being released in the environment with no known effects on ecosystems. Although these materials offer distinct advantages in manufacturing processes, such as odor-free fabric or controlled drug delivery, their fate in nature has yet to be thoroughly investigated. As the size of an already-large NPs market is expected to grow, due to advances in synthetic biology, it is vital that we increase our understanding of their impacts on human, food and natural ecosystems. Recent studies have shown that NPs affect phytoplankton biomass and diversity in the ocean, solely by regulating micronutrients bioavailability. These types of changes could ultimately impact several biogeochemical cycles, as phytoplankton are responsible for almost half of the primary production on earth. Consequently, this study was designed to evaluate the impact of various concentrations (0µM, 20µM, 40µM, 80µM and 100µM) of several manufactured nanoparticles (gold, carbon and iron) on the dynamics of four economically important microalgae strains. Responses, such as chlorophyll content, protein, lipid content, lipid profile, biomass and cell morphology were monitored over a period of two weeks. No significant acute toxicity was exhibited within the first 24 hours of exposure. However, after 4 days, a remarkably high mortality rate was detected with increasing NPs concentrations of Fe60, C80 and Au60. Iron suspensions were found to be more toxic to the microalgae strains tested than those of Gold and Carbon under comparable regimes. Further investigations with other, either positively or negatively charged nanoparticles, should provide a deeper understanding on the impacts on these engineered materials in our ecosystems. 

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2. Mechanism of nanomaterial-induced lipid droplet formation in Raphidocelis subcapitata is mediated by charge properties

   https://doi.org/10.3389/fpls.2025.1681466  

   McKeel, Emma; Kim, Hye-In; Jeon, Su-Ji; McKinnon, Britta; Giraldo, Juan Pablo; Klaper, Rebecca (October 2025, Frontiers in Plant Science)

   Increasing the production of renewable energy will be critical to achieving global sustainability goals in the coming decades. Biofuels derived from microalgae have great potential to contribute to this production. However, cultivating algae with sufficient neutral lipid content, while maintaining high growth rates, is a continual challenge in making algal-derived biofuels a reality. Previous work has shown that exposure to polymer-functionalized carbon dots can increase the lipid content of the microalgaeRaphidocelis subcapitata. This study investigates this finding, aiming to determine the mechanisms underlying this effect and if altering nanoparticle surface charge mediates the mechanism of action of the carbon dots used. Carbon dots with both negative and positive surface charges were added to microalgal cultures, and the impacts of this exposure were analyzed using high-content imaging, growth measurements, and chlorophyll content measurements. Results indicate that positively charged carbon dots induce a nano-specific increase in lipid content but also cause decreases in growth. Additionally, the mechanism of action of each nanoparticle was examined by conducting a morphological comparison to treatments with known mechanisms of action. This analysis showed that negatively charged carbon dots cause similar impacts toR. subcapitataas nitrogen deprivation. Nitrogen deprivation is known to increase lipid content in microalgae. The findings of this study suggest that carbon dots may have surface charge dependent effects on the lipid metabolism ofR. subcapitata. Future work should consider the use of carbon dots with varied surface charge densities for enhancing algae biofuel production in bioreactors. 

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3. Modeling performance of rhamnolipid-coated engineered magnetite nanoparticles for U( vi ) sorption and separation

   https://doi.org/10.1039/d0en00416b  

   Sharma, Neha; Ghosh, Anushree; Fortner, John D.; Giammar, Daniel E. (July 2020, Environmental Science: Nano)

   Based on tunable properties, engineered nanoparticles (NPs) hold significant promise for water treatment technologies. Motivated by concerns regarding toxicity and non-biodegradability of some nanoparticles, we explored engineered magnetite (Fe 3 O 4 ) nanoparticles with a biocompatible coating. These were prepared with a coating of rhamnolipid, a biosurfactant primarily obtained from Pseudomonas aeruginosa . By optimizing synthesis and phase transfer conditions, particles were observed to be monodispersed and stable in water under environmentally relevant pH and ionic strength values. These materials were evaluated for U( vi ) removal from water at varying dissolved inorganic carbon and pH conditions. The rhamnolipid-coated iron oxide nanoparticles (IONPs) showed high sorption capacities at pH 6 and pH 8 in both carbonate-free systems and systems in equilibrium with atmospheric CO 2 . Equilibrium sorption behavior was interpreted using surface complexation modeling (SCM). Two models (diffuse double layer and non-electrostatic) were evaluated for their ability to account for U( vi ) binding to the carboxyl groups of the rhamnolipid coating as a function of the pH, total U( vi ) loading, and dissolved inorganic carbon concentration. The diffuse double layer model provided the best simulation of the adsorption data and was sensitive to U( vi ) loadings as it accounted for the change in the surface charge associated with U( vi ) adsorption. 

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4. Critical Review on Nanomaterials for Enhancing Bioconversion and Bioremediation of Agricultural Wastes and Wastewater

   https://doi.org/10.3390/en15155387  

   Salehi, Bahare; Wang, Lijun (August 2022, Energies)

   Anaerobic digestion (AD), microalgae cultivation, and microbial fuel cells (MFCs) are the major biological processes to convert organic solid wastes and wastewater in the agricultural industry into biofuels, biopower, various biochemical and fertilizer products, and meanwhile, recycle water. Various nanomaterials including nano zero valent irons (nZVIs), metal oxide nanoparticles (NPs), carbon-based and multicompound nanomaterials have been studied to improve the economics and environmental sustainability of those biological processes by increasing their conversion efficiency and the quality of products, and minimizing the negative impacts of hazardous materials in the wastes. This review article presented the structures, functionalities and applications of various nanomaterials that have been studied to improve the performance of AD, microalgae cultivation, and MFCs for recycling and valorizing agricultural solid wastes and wastewater. The review also discussed the methods that have been studied to improve the performance of those nanomaterials for their applications in those biological processes. 

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5. A fiddler crab reduces plant growth in its expanded range

   https://doi.org/10.1002/ecy.4203  

   Martínez‐Soto, Kayla S.; Johnson, David S. (December 2023, Ecology)

   Abstract Species across the planet are shifting or expanding their ranges because of climate change. These are climate migrants. Although climate migrants are well documented, their impacts on recipient ecosystems are not. Climate migrants that are also ecosystem engineers (species that modify or create habitats) will likely have profound effects on ecosystems. The Atlantic marsh fiddler crab,Minuca pugnax, is a burrowing crab that recently expanded its range into the northeastern United States. In its historical range,M. pugnaxenhances the aboveground growth of the cordgrassSpartina alterniflora, a plant critical to marsh persistence. In a control‐impact study, however, we found thatSpartinaaboveground biomass was 40% lower whenM. pugnaxwas present. Thus, the positive effect ofM. pugnaxonSpartinaaboveground biomass flipped to a negative one in its expanded range.Spartinabelowground biomass was also 30% lower on average when crabs were present, a finding consistent with what is seen in the historical range. These impacts onSpartinaare likely due to burrowing byM. pugnax.Benthic microalgae was, on average, 45% lower when crabs were present. Fiddler crabs eat benthic microalgae, and these results suggest that fiddler crabs can control algal biomass via grazing. Because fiddler crabs reduced the biomass of foundational primary producers in its expanded range, our results imply thatM. pugnaxcan influence other saltmarsh functions such as carbon storage and accretion as they expand north. Most strikingly, our results suggest that as species expand or shift their range with climate change, not only can they have profound impacts in their new ranges but those impacts can be the inverse of what is seen in their historical ranges. 

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