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Evaluating cell surface extraction methods for improved assessment of silver nanoparticle bioaccumulation
Arin Kantarciyan1, Inés Segovia-Campos1, Vera I Slaveykova1
1University of Geneva, Faculty of Sciences, Department F.-A. Forel for Environmental and Aquatic Sciences, Environmental Biogeochemistry and Ecotoxicology, Bvd Carl-Vogt 66, 1211 Geneva, Switzerland.
Aquatic Toxicology (Amsterdam, Netherlands)
|April 9, 2025
Summary
Developing new methods to measure silver in phytoplankton is crucial. This study optimized ligand-based extraction for silver ions and silver nanoparticles, improving bioaccumulation assessments.
Area of Science:
- Environmental Science
- Environmental Chemistry
- Ecotoxicology
Background:
- Accurate quantification of bioaccumulated silver (Ag) in phytoplankton is vital for understanding its environmental fate and ecological impact.
- Existing methods for differentiating surface-bound and internalized Ag, especially from silver nanoparticles (AgNPs), are limited.
- Phytoplankton species like Chlamydomonas reinhardtii and Cyclotella meneghiniana are key primary producers and important models for aquatic ecotoxicity studies.
Purpose of the Study:
- To develop and optimize effective methods for extracting adsorbed and internalized silver from phytoplankton exposed to silver ions (Ag+) or AgNPs.
- To evaluate the efficacy of various biologically relevant ligands and oxidants in Ag extraction.
- To assess the impact of extraction agents on AgNP stability and microalgal cell integrity.
Main Methods:
- Tested ligands (l-histidine, l-glutamine, l-cysteine, d-penicillamine) for Ag+ desorption from Ag+-exposed phytoplankton.
- Optimized ligand concentration and contact time for efficient Ag+ extraction.
- Developed a sequential extraction protocol for AgNPs involving cell resuspension and oxidative dissolution using hydrogen peroxide (H2O2).
- Investigated the effects of extraction agents on AgNP stability and microalgal membrane integrity.
Main Results:
- D-penicillamine and l-cysteine showed high efficiency in desorbing Ag+ from Ag+-treated cells, with optimal conditions at 1 mmol L⁻¹ ligand and 5 min contact time.
- Two sequential resuspensions in Ag-free medium effectively removed loosely bound AgNPs.
- A combination of H2O2 (0.5 mmol L⁻¹) and l-cysteine or d-penicillamine (1 mmol L⁻¹) effectively removed Ag from AgNP-exposed phytoplankton cell walls.
- Extraction agents generally did not harm unexposed cells, but H2O2 caused minor membrane damage in diatoms exposed to AgNPs.
- AgNP dissolution was observed with l-histidine, d-penicillamine, and H2O2.
Conclusions:
- Optimized ligand-based extraction methods improve the assessment of Ag adsorption and internalization in phytoplankton.
- A sequential extraction protocol combining physical removal and oxidative dissolution is effective for AgNPs.
- Species-specific extraction methodologies are necessary for accurate Ag bioaccumulation studies in phytoplankton.
- The findings provide crucial insights for developing standardized protocols in ecotoxicological assessments of silver nanoparticles.
