Toxicity of Silver–Chitosan Nanocomposites to Aquatic Species †
1
Laboratory of Environmental Toxicology, National Institute of Chemical Physics and Biophysics, 12618 Tallinn, Estonia
2
School of Science, Tallinn Technical University, 19086 Tallinn, Estonia
*
Author to whom correspondence should be addressed.
†
Presented at the International Conference EcoBalt 2023 “Chemicals & Environment”, Tallinn, Estonia, 9–11 October 2023.
Proceedings 2023, 92(1), 17; https://doi.org/10.3390/proceedings2023092017
Published: 21 November 2023
(This article belongs to the Proceedings of International Conference EcoBalt 2023 "Chemicals & Environment")
According to the World Health Organization, antimicrobial resistance (AMR) is one of the top ten global public health threats, justifying the need for new effective antimicrobials for biomedical applications. For the successful commercialization of any new material, data on its environmental safety are obligatory. Silver (Ag) compounds are widely used in wound dressings as well as disinfectants in healthcare due to their antibacterial activity and assumingly low risk of developing AMR.
In this study, the potential environmental hazard of silver–chitosan nanocomposites (nAgCSs) was evaluated. nAgCSs were synthesized by the reduction of the AgNO3 with trisodium citrate and stabilized by coating with low molecular-weight chitosan (50–190 kDa). The amount of chitosan (CS) in the nanocomposites varied, resulting in three different types of nanocomposites with the weight ratio of Ag to CS 1:0.3 (nAgCS-0.3), 1:1 (nAgCS-1) and 1:3 (nAgCS-3). The toxicities of different Ag-CS nanocomposites and citrate-coated Ag nanoparticles were tested on the naturally luminescent bacterium Vibrio fischeri and microcrustaceans Daphnia magna and Thamnocephalus platyurus.
The primary size of nAgCSs was ~50 nm. In deionized water, the average hydrodynamic sizes were in the nanoscale (≤100 nm) and the surface charges were positive (16–26 mV). The toxicity of the studied Ag nanomaterials was evaluated using the bacterial kinetic bioluminescence inhibition and viability test [1,2] and acute immobilization/mortality tests with crustaceans [3,4]. The nAgCSs were about 10–500 fold more toxic to microcrustaceans D. magna (48-h EC50 = 0.044–0.077 mg Ag/L) and T. platyurus (24-h EC50 = 0.19–0.261 mg Ag/L) than to bacterium V. fischeri (30-min EC50=3–26 mg Ag/L). Taking into the account the data obtained with this multi-trophic test battery the synthesized silver-chitosan nanocomposites could be classified as “extremely toxic” [L(E)C50 ≤ 0.1 mg/L] [5]. Interestingly, the nanocomposites with the highest chitosan content (nAgCS-3) were the most toxic to bacteria V. fischeri but the least toxic to the crustaceans. The data obtained show that the chitosan–silver nanocomposites may pose a hazard to aquatic organisms and must be handled accordingly.
Author Contributions
Conceptualization, K.K. and A.K.; methodology, formal analysis, investigation and writing, K.K., A.K., M.S., J.L. and I.B. All authors have read and agreed to the published version of the manuscript.
Funding
This research was funded by the Estonian Research Council grant PRG 749.
Institutional Review Board Statement
Not applicable.
Informed Consent Statement
Not applicable.
Data Availability Statement
Not applicable.
Acknowledgments
This research was conducted using the NAMUR+ core facility supported by the Estonian Research Council (TT13).
Conflicts of Interest
The authors declare no conflict of interest.
References
- ISO 21338:2010; Water Quality—Kinetic Determination of the Inhibitory Effects of Sediment, Other Solids and Coloured Samples on the Light Emission of Vibrio fischeri (Kinetic Luminescent Bacteria Test). International Organization for Standardization (ISO): Geneva, Switzerland, 2010.
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- ISO 14380:2011; Water Quality—Determination of the Acute Toxicity to Thamnocephalus platyurus (Crustacea, Anostraca). International Organization for Standardization (ISO): Geneva, Switzerland, 2011.
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MDPI and ACS Style
Sihtmäe, M.; Laanoja, J.; Blinova, I.; Kahru, A.; Kasemets, K. Toxicity of Silver–Chitosan Nanocomposites to Aquatic Species. Proceedings 2023, 92, 17. https://doi.org/10.3390/proceedings2023092017
AMA Style
Sihtmäe M, Laanoja J, Blinova I, Kahru A, Kasemets K. Toxicity of Silver–Chitosan Nanocomposites to Aquatic Species. Proceedings. 2023; 92(1):17. https://doi.org/10.3390/proceedings2023092017
Chicago/Turabian StyleSihtmäe, Mariliis, Jüri Laanoja, Irina Blinova, Anne Kahru, and Kaja Kasemets. 2023. "Toxicity of Silver–Chitosan Nanocomposites to Aquatic Species" Proceedings 92, no. 1: 17. https://doi.org/10.3390/proceedings2023092017
