Assessment of biopolymer stabilized silver nanoparticle for their ecotoxicity on Ceriodaphnia cornuta and antibiofilm activity

• Biopolymer stabilized (sodium alginate) silver nanoparticles (SA-AgNPs) was synthesized and physico-chemically characterized by UV–vis spectroscopy, XRD, FTIR, SEM, EDAX and TEM.
• SA-AgNPs effectively inhibited the biofilm growth of Listeria monocytogenes and Vibrio parahaemolyticus.
• Ecotoxicity assessment showed less toxic nature of SA-AgNPs on freshwater crustaceans Ceriodaphnia cornuta (LC50: 7.94 μg L−1).
• Ag+ accumulation by C. cornuta was increased when the concentration of SA-AgNPs was increased.

Sodium alginate (biopolymer) stabilized silver nanoparticles (SA-AgNPs) were synthesized and characterized by UV–vis spectroscopy, XRD, FTIR, SEM, EDAX and TEM. UV–vis spectra recorded the absorbance peak at 407 nm due to its surface plasmon resonance. XRD measurements indicated the crystalline nature of particle with various Bragg’s reflection peaks at (111), (200) (220), (311) and (222) planes. FTIR spectra showed the possible functional groups at 3443, 1616, 1384, 1092, 1209, 835 and 774 cm−1. SEM and TEM showed that the particles were spherical in shape and the size was in the range of 23 ± 2 nm. EDAX analysis showed that the weight percentage and elemental silver in the composition was 57.80. The ecotoxicity of SA-AgNPs was assessed on the freshwater crustacean, Ceriodaphnia cornuta. SA-AgNPs caused 100% mortality of C. cornuta at 40 μg L−1, whereas AgNO3 caused100% mortality of C. cornuta at 10 μg L−1. The accumulation of Ag+ by C. cornuta was increased at increasing concentration and reached 3.4 μg/g dry weight at 50 μg L−1. C. cornuta exposed to AgNO3 showed blackening of intestine at 5 and 10 μg L−1. On the otherhand, the visible uptake, ingestion and accumulation of SA-AgNPs in the intestine of C. cornuta were clearly visualized under CLSM after treated with 10, 20 40 and 50 μg L−1. The abnormal swimming, reduced heart rate and thoracic limb movement of C. cornuta were also observed after exposure to 50 μg L−1of SA-AgNPS. The synthesized SA-AgNPs were tested for its antibiofilm activity against Gram positive (Listeria monocytogenes) and Gram negative (Vibrio parahaemolyticus) bacteria. SA-AgNPs effectively inhibited the biofilm growth of L. monocytogenes and V. parahaemolyticus at 75 μg mL−1.

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