Gold nanoparticles (AuNPs) are increasingly being used in biomedical applications such as imaging or photothermal cancer therapy due to the unique optical properties of their surface plasmon resonances. To maximize efficacy of these applications, it is necessary to use an optimal wavelength of light to excite AuNPs, but intracellular aggregation can alter their plasmon resonances. It is unclear how functionalization of AuNPs with poly(ethylene) glycol (PEG), a material commonly used in biomedical applications and known to decrease cellular uptake, impacts these intracellular changes in AuNP optical properties. In this study, we measure changes in the optical spectra of 100nm PEGylated AuNPs internalized by Sk-Br-3 breast adenocarcinoma cells and compare them to spectra of bare AuNPs. We quantify how these changes occur over time and increasing AuNP exposure doses using UV-Vis spectroscopy and darkfield hyperspectral imaging. Our results show that even for PEGylated AuNPs, there are significant increases in scattering wavelengths over time associated specifically with cellular interactions as opposed to changes related to serum incubation alone. For example, after 24 hours of cellular incubation, average scattering spectra increased by as much as 32.8�12.4 nm. Under the same conditions, this increase was much greater for AuNPs without PEG (up to 78.6�23.5nm increase). Overall, we conclude that while optical changes resulting from intracellular AuNP interactions are smaller for PEGylated AuNPs than bare AuNPs, increases in optical spectra over time and concentration are still significant for the surface functionalized AuNPs. Our findings highlight important design considerations for applications involving plasmonic AuNPs in biomedical environments.

Quantifying the impact of surface functionalization on optical spectra of cell-internalized gold nanoparticles

248th National Meeting (2014)

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