title: Imaging the uptake of gold nanoshells in live cells using plasmon resonance enhanced four wave mixing microscopy.
abstract: Gold nanoshells (GNS) are novel metal nanoparticles exhibiting attractive optical properties which make them highly suitable for biophotonics applications. We present a novel investigation using plasmon-enhanced four wave mixing microscopy combined with coherent anti-Stokes Raman scattering (CARS) microscopy to visualize the distribution of 75 nm radius GNS within live cells. During a laser tolerance study we found that cells containing nanoshells could be exposed to < 2.5 mJ each with no photo-thermally induced necrosis detected, while cell death was linearly proportional to the power over this threshold. The majority of the GNS signal detected was from plasmon-enhanced four wave mixing (FWM) that we detected in the epi-direction with the incident lasers tuned to the silent region of the Raman spectrum. The cellular GNS distribution was visualized by combining the epi-detected signal with forwards-detected CARS at the CH2 resonance. The applicability of this technique to real-world nanoparticle dosing problems was demonstrated in a study of the effect of H2S on nanoshell uptake using two donor molecules, NaHS and GYY4137. As GYY4137 concentration was increased from 10 µM to 1 mM, the nanoshell pixel percentage as a function of cell volume (PPCV) increased from 2.15% to 3.77%. As NaHS concentration was increased over the same range, the nanoshell PPCV decreased from 12.67% to 11.47%. The most important factor affecting uptake in this study was found to be the rate of H2S release, with rapid-release from NaHS resulting in significantly greater uptake.
authors.affiliation: School of Physics, University of Exeter, Exeter, Devon, UK. n.l.garrett@exeter.ac.uk
authors.forename: Natalie
authors.initials: N
authors.lastname: Garrett
authors.forename: Matt
authors.initials: M
authors.lastname: Whiteman
authors.forename: Julian
authors.initials: J
authors.lastname: Moger
mesh_terms: D000818:Animals; D001693:Biological Transport, Active; D002460:Cell Line; D006046:Gold; D006862:Hydrogen Sulfide; D007091:Image Processing, Computer-Assisted; D051379:Mice; D008853:Microscopy / Q000379:methods*; D009025:Morpholines; D057145:Nanoshells; D055620:Optical Phenomena; D009946:Organothiophosphorus Compounds; D059010:Single-Cell Analysis / Q000379:methods*; D013059:Spectrum Analysis, Raman; D020349:Surface Plasmon Resonance / Q000379:methods*
chemical_list: C529376:GYY 4137; D009025:Morpholines; D009946:Organothiophosphorus Compounds; D006046:Gold; D006862:Hydrogen Sulfide