Dispersion stabilization of silver nanoparticles in synthetic lung fluid studied under in situ conditions

Abstract

The dispersion stabilization of silver nanoparticles (AgNPs) in synthetic lung fluid was studied to interrogate the effects on colloidal stability due to the principal constituents of the fluid. The colloidal stability of 20 nm citrate-AgNPs dispersed in the presence of each constituent of the synthetic lung fluid (individually, the complete fluid, and without additives) was observed during titration of increasing sodium chloride concentration. A variety of complementary in situ measurement techniques were utilized, including dynamic light scattering, ultraviolet-visible absorption spectroscopy, atomic force microscopy, and small-angle X-ray scattering, which provided a collective set of information that enabled far better understanding of the dispersion behavior in the fluid than any one technique alone. It was observed that AgNPs continued to adsorb bovine serum albumin (BSA) protein from the synthetic lung fluid solution as the sodium chloride concentration increased, until a maximum BSA coating was achieved prior to reaching the physiological sodium chloride concentration of 154 mmol L⁻¹. BSA was determined to be the constituent of the synthetic lung fluid that is required to provide colloidal stability at high salt loadings, though the phospholipid constituent exerts a subtle effect. Additionally, as AgNPs are a distinctly different class of nanoparticles apart from the carbon nanotubes and titanium dioxide nanoparticles initially reported to be dispersible using this fluid, this work also demonstrates the broad applicability of synthetic lung fluid in providing stable dispersions for engineered nanoparticles for use in biological assays.

Keywords::

• AgNPs
• synthetic alveolar lavage fluid
• nanoparticle dispersion protocol
• nanoEHS
• SAXS flow cell

Acknowledgments

Use of the Advanced Photon Source at Argonne National Laboratory was supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. ChemMatCARS Sector 15 is principally supported by the National Science Foundation/Department of Energy under grant number CHE-0535644. Dr Jan Ilavsky, X-ray Science Division, and Dr Yu-Sheng Chen, ChemMatCARS, both of the Advanced Photon Source, are acknowledged for assistance with measurements and SAXS data reduction. The authors thank Dr John E. Bonevich, NIST Metallurgy Division, for providing the TEM image.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper. *Certain trade names and company products are mentioned in the text or identified in illustrations in order to specify adequately the experimental procedure and equipment used. In no case does such identification imply recommendation or endorsement by National Institute of Standards and Technology, nor does it imply that the products are necessarily the best available for the purpose.