Photo-induced transformations of polyvinylpyrrolidone coatings on gold nanoparticles and effects on colloidal stability
Stacey M. Louie, Justin Gorham, Jiaojie Tan, Vincent A. Hackley
Polymeric coatings are commonly applied to impart functionality and colloidal stability to engineered nanoparticles. In natural environments, transformations of the coating can modify the particle transport behavior, but the mechanisms and outcomes of these transformations have not yet been thoroughly evaluated. This study investigates the photo-transformations of polyvinylpyrrolidone (PVP) coatings on gold nanoparticles (AuNPs) under ultraviolet (UV) irradiation and the impact on the AuNP colloidal stability. Multiple orthogonal characterization methods were applied, including dynamic light scattering (DLS), attenuated total reflectance - Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and electrospray - differential mobility analysis (ES-DMA). Rapid oxidation of the PVP coating occurred upon UV exposure. The transformed PVP largely persisted on the AuNP surface, albeit in a collapsed polymer layer around the AuNP surface. This transformation resulted in drastically diminished colloidal stability of the AuNPs, consistent with loss of steric stabilization. While the residual coating modified the interaction of the AuNPs with calcium counterions, it did not prevent subsequent stabilization by humic acid. This study clearly shows that UV exposure can result in significant transformations of polymeric coatings on engineered NPs that correlate with changes to their colloidal stability. More broadly, we demonstrate a characterization tool set to comprehensively identify the physicochemical transformations of polymeric surface coatings on nanoparticles.
Royal Society of Chemistry Journal Environmental Science: Nano
, Gorham, J.
, Tan, J.
and Hackley, V.
Photo-induced transformations of polyvinylpyrrolidone coatings on gold nanoparticles and effects on colloidal stability, Royal Society of Chemistry Journal Environmental Science: Nano, [online], https://doi.org/10.1039/c7en00411g, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=922687
(Accessed March 5, 2024)