Silver nanoparticle behaviour in lake water depends on their surface coating

Area of Science:

• Environmental Science
• Nanotechnology
• Analytical Chemistry

Background:

• Silver nanoparticles (AgNPs) are increasingly used, raising concerns about their environmental fate.
• Understanding AgNP stability in aquatic systems is crucial for environmental risk assessment.
• Dissolved organic matter (DOM) is a key factor influencing nanoparticle behavior in natural waters.

Purpose of the Study:

• To investigate the stability of silver nanoparticles (AgNPs) with different coatings (citrate, polyvinyl pyrrolidone, lipoic acid) and sizes (20, 50nm) in lake water.
• To determine the influence of DOM type (pedogenic, aquagenic) and concentration on AgNP transformation.
• To elucidate the role of surface coating and exposure time on AgNP behavior in a complex aquatic matrix.

Main Methods:

• Asymmetric flow field-flow fractionation (AsFlFFF) for separation and characterization.
• Surface plasmon resonance (SPR) for monitoring aggregation.
• Single particle inductively coupled plasma mass spectrometry (SP-ICP-MS) for elemental analysis and particle quantification.

Main Results:

• AgNP stability is a complex interplay of surface coating, DOM presence, and exposure time.
• Polyvinyl pyrrolidone (PVP) coatings provided greater AgNP stability compared to citrate (CIT) and lipoic acid (LIP) coatings.
• Aquagenic DOM (extracellular polymeric substances, EPS) stabilized AgNPs more effectively than pedogenic DOM (Suwannee River Humic Acids, SRHA).

Conclusions:

• Surface coating is the primary determinant of AgNP behavior in lake water.
• DOM composition significantly impacts AgNP stability, with aquagenic sources showing higher stabilization potential.
• Accurate environmental risk assessment requires considering both AgNP properties and the specific characteristics of DOM in aquatic ecosystems.