Abstract
When plasmonic nanoparticles (NPs) are internalized by cells and agglomerate within intracellular vesicles, their optical spectra can shift and broaden as a result of plasmonic coupling of NPs in close proximity to one another. For such optical changes to be accounted for in the design of plasmonic NPs for light-based biomedical applications, quantitative design relationships between designable factors and spectral shifts need to be established. Here we begin building such a framework by investigating how functionalization of gold NPs (AuNPs) with biocompatible poly(ethylene) glycol (PEG), and the serum conditions in which the NPs are introduced to cells impact the optical changes exhibited by NPs in a cellular context. Utilizing darkfield hyperspectral imaging, we find that PEGylation decreases the spectral shifting and spectral broadening experienced by 100 nm AuNPs following uptake by Sk-Br-3 cells, but up to a 33 ± 12 nm shift in the spectral peak wavelength can still occur. The serum protein-containing biological medium also modulates the spectral changes experienced by cell-exposed NPs through the formation of a protein corona on the surface of NPs that mediates NP interactions with cells: PEGylated AuNPs exposed to cells in serum-free conditions experience greater spectral shifts than in serum-containing environments. Moreover, increased concentrations of serum (10, 25, or 50 %) result in the formation of smaller intracellular NP clusters and correspondingly reduced spectral shifts after 5 and 10 h NP-cell exposure. However, after 24 h, NP cluster size and spectral shifts are comparable and become independent of serum concentration. By elucidating the impact of PEGylation and serum concentration on the spectral changes experienced by plasmonic NPs in cells, this study provides a foundation for the optical engineering of plasmonic NPs for use in biomedical environments.
| Original language | English (US) |
|---|---|
| Article number | 303 |
| Journal | Nanoscale Research Letters |
| Volume | 11 |
| Issue number | 1 |
| DOIs | |
| State | Published - Dec 1 2016 |
Funding
This work was supported in part by the Robert A. Welch Foundation (C-1598). A. Chen gratefully acknowledges support from the National Science Foundation Graduate Research Fellowship Program (0940902) and from the Keck Center of the Gulf Coast Consortia through the Nanobiology Interdisciplinary Graduate Training Program (NIH Grant T32EB009379). M. Jackson acknowledges the Rice Undergraduate Scholars Program. A. Lin acknowledges support from the Medical Scientist Training Program at Baylor College of Medicine, the Edward and Josephine Hudson Scholarship, and the Ruth L. Kirschstein National Research Service Awards for Individual Predoctoral MD/PhD Fellows (5F30CA165686) by NIH and NCI. We thank K. Dunner, Jr., of The University of Texas M.D. Anderson Cancer Center High Resolution Electron Microscopy Facility (Institutional Core Grant #CA16672) and D. Townley of Baylor College of Medicine’s Integrated Microscopy Core for TEM sample processing and imaging services, and thank S. Link and V. Mack for their thoughtful discussions.
Keywords
- Cells
- Gold nanoparticles
- Hyperspectral imaging
- Nano-bio interactions
- Nanomedicine
- Plasmonics
- Poly(ethylene glycol)
- Protein corona
- Serum
- Spectral shifting
ASJC Scopus subject areas
- Condensed Matter Physics
- General Materials Science