The algal toxicity of silver engineered nanoparticles and detoxification by exopolymeric substances.
In this study, we report that silver ions (Ag(+)) from the oxidative dissolution of silver engineered nanoparticles (Ag-ENs) determined the EN toxicity to the marine diatom Thalassiosira weissflogii. Most of the Ag-ENs formed non-toxic aggregates (>0.22 microm) in seawater. When the free Ag(+) concentration ([Ag(+)](F)) was greatly reduced by diafiltration or thiol complexation, no toxicity was observed, even though the Ag-ENs were better dispersed in the presence of thiols with up to 1.08 x 10(-5) M Ag-ENs found in the <0.22 microm fraction, which are orders of magnitude higher than predicted for the natural aquatic environment. The secretion of polysaccharide-rich algal exopolymeric substances (EPS) significantly increased at increasing [Ag(+)](F). Both dissolved and particulate polysaccharide concentrations were higher for nutrient-limited cells, coinciding with their higher Ag(+) tolerance, suggesting that EPS may be involved in Ag(+) detoxification.
Miao
Ai-Jun
AJ
Dept. of Marine Science, Texas A&M University at Galveston, Galveston, TX 77551, USA. aijunm@tamug.edu
Schwehr
Kathy A
KA
Xu
Chen
C
Zhang
Sai-Jin
SJ
Luo
Zhiping
Z
Quigg
Antonietta
A
Santschi
Peter H
PH
D017377:Diatoms / Q000187:drug effects* / Q000378:metabolism; D053758:Nanoparticles / Q000737:chemistry / Q000633:toxicity*; D011134:Polysaccharides / Q000378:metabolism*; D012623:Seawater / Q000032:analysis; D012834:Silver / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity*; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity*
D011134:Polysaccharides; D014874:Water Pollutants, Chemical; D012834:Silver