Imaging of plasmonic heating in a living organism.

Controlling and monitoring temperature at the single cell level has become pivotal in biology and medicine. Indeed, temperature influences many intracellular processes and is also involved as an activator in novel therapies. Aiming to assist such developments, several approaches have recently been proposed to probe cell temperature in vitro. None of them have so far been extended to a living organism. Here we present the first in vivo intracellular temperature imaging. Our technique relies on measuring the fluorescence polarization anisotropy of green fluorescent protein (GFP) on a set of GFP expressing neurons in Caenorhabditis elegans (C. elegans). We demonstrate fast and noninvasive monitoring of subdegree temperature changes on a single neuron induced by local photoheating of gold nanoparticles. This simple and biocompatible technique is envisioned to benefit several fields including hyperthermia treatment, selective drug delivery, thermal regulation of gene expression and neuron laser ablation.