B032-0005
NOM Corona of Silver Nanoparticles: Sulfidation-Induced Changes in Molecular Composition

Wednesday, 9 December 2020
Poster
Salimar Cordero, University of Massachusetts Amherst, Civil and Environmental Engineering, Amherst, MA, United States, Martha L Chacon Patino, National High Magnetic Field Laboratory, Tallahassee, United States, Richard Vachet, University of Massachusetts Amherst, Chemistry, Amherst, United States, William C Hockaday, Baylor University, Waco, TX, United States and Boris Lau, University of Massachusetts Amherst, Civil & Env. Engineering, Amherst, United States
Abstract:
Biomolecular coronas are recognized as important mediators in the physiological activity of nanoparticles (NPs). However, in the context of environmental nanoscience, the characteristics of natural organic matter (NOM) corona remain underexplored. We examined two types of commercially available 50 nm silver nanoparticles (AgNPs). The first was functionalized with polyethylene glycol (PEG) and the second with polyvinyl pyrrolidone (PVP). We partially sulfidized each type of AgNP in the presence of an NOM standard as a model for NPs “transformed” under reducing aquatic conditions. We hypothesized that the composition and molecular weight distribution of NOM corona are dependent on 1) sulfidation conditions and 2) polymer functionalized on the surface of AgNPs.

We applied electrospray ionization Fourier-transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR-MS) to characterize the molecular composition of the NOM corona of AgNPs. Our preliminary results indicated that sulfidation shifted both the composition and molecular weight distribution of NOM corona. These shifts are ligand-dependent. After sulfidizing PEG-AgNPs, the NOM corona possessed 1) a higher relative abundance of two compound classes (i.e., CHON and CHOS) and 2) compounds with higher molecular weight. When a lipid-free NOM (LF-NOM) fraction was used (instead of bulk/whole NOM), sulfidized PVP-AgNPs (but not PEG-AgNPs) possessed a corona with more assigned sulfur/oxygen/nitrogen-containing molecules. Regardless of the polymeric ligand composition, LF-NOM corona consisted of species with higher molecular weight. More experiments are currently underway to examine the relative importance of different sulfidation conditions.

Overall, our results provide greater knowledge of NOM corona characteristics that could ultimately influence their environmental partitioning and toxicity. This study also contributes directly to the development of a mechanistic understanding of the molecular processes that control the reactivity and transport of NPs/NOM.

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