Effects of Engineered Nanoparticles on the Assembly of Exopolymeric Substances from Phytoplankton

Abstract

The unique properties of engineered nanoparticles (ENs) that make their industrial applications so attractive simultaneously raise questions regarding their environmental safety. ENs exhibit behaviors different from bulk materials with identical chemical compositions. Though the nanotoxicity of ENs has been studied intensively, their unintended environmental impacts remain largely unknown. Herein we report experimental results of EN interactions with exopolymeric substances (EPS) from three marine phytoplankton species: Amphora sp., Ankistrodesmus angustus and Phaeodactylum tricornutum. EPS are polysaccharide-rich anionic colloid polymers released by various microorganisms that can assemble into microgels, possibly by means of hydrophobic and ionic mechanisms. Polystyrene nanoparticles (23 nm) were used in our study as model ENs. The effects of ENs on EPS assembly were monitored with dynamic laser scattering (DLS). We found that ENs can induce significant acceleration in Amphora sp. EPS assembly; after 72 hours EN-EPS aggregation reached equilibrium, forming microscopic gels of ∼4–6 µm in size. In contrast, ENs only cause moderate assembly kinetic acceleration for A. angustus and P. tricornutum EPS samples. Our results indicate that the effects of ENs on EPS assembly kinetics mainly depend on the hydrophobic interactions of ENs with EPS polymers. The cycling mechanism of EPS is complex. Nonetheless, the change of EPS assembly kinetics induced by ENs can be considered as one potential disturbance to the marine carbon cycle.

Double walled carbon nanotubes promote the overproduction of extracellular protein-like polymers in Nitzschia palea: An adhesive response for an adaptive issue

“…In contrast, the concentration of carbohydrates from the TWEEN extract was significantly higher only at the highest concentration of DWCNTs. As already observed with polystyrene nanoparticles [60], our results suggest a strong hydrophobic interaction between DWCNTs and EPS, which is mainly driven by PLPs. These results corroborate the HPLC results, which showed increases in two PLPs ($174 kDa, $10 kDa) that could be strongly implicated in the observed hydrophobic interaction between EPS and DWCNTs.…”

“…TWEEN 20 was used as a chemical substitute for hydrophobic bonds [59], freeing the EPS linked by hydrophobic interactions to DWCNTs. Considering the high solubility of polysaccharides, the hydrophobicity of EPS is mostly inherent to proteins [49,60]. In this study, carbohydrates and PLPs from the TWEEN extract were strongly correlated ($0.95) with the concentration of DWCNTs.…”

Size-Dependent Toxicity of Silver Nanoparticles to Bacteria, Yeast, Algae, Crustaceans and Mammalian Cells In Vitro

“…In the scientific literature both, uptake of NPs by microbial cells [36] [37] [24] as well as increased dissolution of NPs in the vicinity of microbial cells have been suggested [38] [39] [40]. In case of three marine phytoplankton species exposure to polystyrene NPs increased the production of exopolymers [41] which indicates that NPs may significantly interfere with cellular physiology. However as the interaction of NPs with living cells and vice versa is a dynamic process, determination of the exact sequence of cellular events triggered by NP exposure remains to be elucidated.…”

Ecotoxicological effects of carbon nanotubes and cellulose nanofibers in Chlorella vulgaris

“…Figure 6F shows gum-like cellulose surrounding the microalgae. Previous studies have shown that the interaction between NPs and phytoplankton produced EPS [19,44]. The increased production of EPS was found to be a general response to the presence of pollutants [45].…”