A lack of mechanistic understanding of nanomaterial interactions with plants and algae cell walls limits the advancement of nanotechnology-based tools for sustainable agriculture. We systematically investigated the influence of nanoparticle charge on the interactions with model cell wall surfaces built with cellulose or pectin and performed a comparative analysis with native cell walls of Arabidopsis plants and green algae (Choleochaete). The high affinity of positively charged carbon dots (CDs) (46.0 ± 3.3 mV, 4.3 ± 1.5 nm) to both model and native cell walls was dominated by the strong ionic bonding between the surface amine groups of CDs and the carboxyl groups of pectin. In contrast, these CDs formed weaker hydrogen bonding with the hydroxyl groups of cellulose model surfaces. The CDs of similar size with negative (−46.2 ± 1.1 mV, 6.6 ± 3.8 nm) or neutral (−8.6 ± 1.3 mV, 4.3 ± 1.9 nm) ζ-potentials exhibited negligible interactions with cell walls. Real-time monitoring of CD interactions with model pectin cell walls indicated higher absorption efficiency (3.4 ± 1.3 10−9) and acoustic mass density (313.3 ± 63.3 ng cm–2) for the positively charged CDs than negative and neutral counterparts (p < 0.001 and p < 0.01, respectively). The surface charge density of the positively charged CDs significantly enhanced these electrostatic interactions with cell walls, pointing to approaches to control nanoparticle binding to plant biosurfaces. Ca2+-induced cross-linking of pectin affected the initial absorption efficiency of the positively charged CD on cell wall surfaces (∼3.75 times lower) but not the accumulation of the nanoparticles on cell wall surfaces. This study developed model biosurfaces for elucidating fundamental interactions of nanomaterials with cell walls, a main barrier for nanomaterial translocation in plants and algae in the environment, and for the advancement of nanoenabled agriculture with a reduced environmental impact.
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This content will become publicly available on January 1, 2025
The effect of nanoparticle surface charge on freshwater algae growth, reproduction, and lipid production
Surface charge is a key characteristic of nanoparticles which has great potential to impact the interactions of nanoparticles and biological systems. Understanding the role charge plays in these interactions is key to determining the ecological risks of nanoparticle exposure and informing sustainable nanoparticle design. In this study, the model freshwater algae Raphidocelis subcapitata was exposed to carbon dots (CDs) functionalized with polymers to have positive, negative, or neutral surface charges to examine the impact of nanoparticle surface charge on nano-algae interactions. Traditional toxicological endpoints of survival and growth inhibition were measured. Additionally, morphological impacts on whole cells, individual organelles, and cellular components were quantified using high-content fluorescence microscopy, demonstrating one of the first uses of high-content imaging in microalgae. Results indicate that PEI functionalized, positively charged CDs are most toxic to green algae (EC50 42.306 μg/L), but that CDs with negative charge induce sublethal impacts on algae. PEI-CD toxicity is hypothesized to be related to electrostatic interactions between CDs and the algal cell wall, which lead to significant cell aggregation. Interestingly, morphological data suggests that exposure to both positively and negatively charged CDs leads to increased neutral lipid droplet formation, a possible indicator of nutrient stress. Further investigation of the mechanisms underlying impacts of nanoparticle surface charge on algae biology can lead to more sustainable nanoparticle design and environmental protections.
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- Award ID(s):
- 2001611
- NSF-PAR ID:
- 10485228
- Publisher / Repository:
- The Royal Society of Chemistry
- Date Published:
- Journal Name:
- Environmental Science: Nano
- ISSN:
- 2051-8153
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Background Agriculture faces significant global challenges including climate change and an increasing food demand due to a growing population. Addressing these challenges will require the adoption of transformative innovations into biotechnology practice, such as nanotechnology. Recently, nanomaterials have emerged as unmatched tools for their use as biosensors, or as biomolecule delivery vehicles. Despite their increasingly prolific use, plant-nanomaterial interactions remain poorly characterized, drawing into question the breadth of their utility and their broader environmental compatibility.
Results Herein, we characterize the response of
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Abstract Cellular uptake and expulsion mechanisms of engineered mesoporous silica nanoparticles (MSNPs) are important in their design for novel biomolecule isolation and delivery applications such as nanoharvesting, defined as using nanocarriers to transport and isolate valuable therapeutics (secondary metabolites) out of living plant organ cultures (e.g., hairy roots). Here, temperature‐dependent MSNP uptake and recovery processes in hairy roots are examined as a function of surface chemistry. MSNP uptake into hairy roots and time‐dependent expulsion are quantified using Ti content (present for biomolecule binding) and fluorescence spectroscopy of fluorescently tagged MSNPs, respectively. The results suggest that functionalization and surface charge (regulated by amine group attachment) play the biggest role in the effectiveness of uptake and recovery. Comparison of MSNP interactions with hairy roots at 4 and 23 °C shows that weakly charged MSNPs functionalized only with Ti are taken up and expelled by thermally activated mechanisms, while amine‐modified positively charged particles are taken up and expelled mainly by direct penetration of cell walls. Amine‐functionalized MSNPs move spontaneously in and out of plant cells by dynamic exchange with a residence time of 20 ± 5 min, suggesting promise as a biomolecule nanoharvesting platform for plant organ cultures.
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