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

Abstract

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 407nm 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 774cm−1. SEM and TEM showed that the particles were spherical in shape and the size was in the range of 23±2nm. 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 40μgL−1, whereas AgNO3 caused100% mortality of C. cornuta at 10μgL−1. The accumulation of Ag+ by C. cornuta was increased at increasing concentration and reached 3.4μg/g dry weight at 50μgL−1.C. cornuta exposed to AgNO3 showed blackening of intestine at 5 and 10μgL−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 50μgL−1. The abnormal swimming, reduced heart rate and thoracic limb movement of C. cornuta were also observed after exposure to 50μgL−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 75μgmL−1.