POLARIZATION-MODULATED LOCK-IN IMAGING OF NON-SPHERICAL GOLD NANOPARTICLE DYNAMICS IN LIVE AND APOPTOTIC CELLS

The geometrical shape of gold nanoparticles plays an essential rule in their biomarker functionality. Direct optical microscopy observations on the dynamics of nanoparticles with different geometries can produce valuable information on their environment and its interaction with the particles themselves. This information is useful for cell research and therapy applications. However, most conventional bio-imaging methods cannot resolve the orientations of non-spherical particles because of the required nanoparticle size. The optical signal of the gold nanoparticles is also strongly limited in many real-life environments, which are noisy and require diluted concentrations.

Here we address these limitations by using the special light characteristics that are caused from the nanoparticles geometrical shape. Using lock-in amplification methods, modulated by the polarization dependency of anisotropic gold nano rods, we report that our method achieved enhancement of the rods imaging inside live cell and cells in various states of apoptosis. Our method resolved the intracellular nanoparticle orientations, and allowed better differentiation between adjacent agents.