Mapping Intracellular Temperature Using Green Fluorescent Protein

Jon S. Donner†, Sebastian A. Thompson†, Mark P. Kreuzer†, Guillaume Baffou‡, and Romain Quidant*†§

^† ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, 08860 Castelldefels (Barcelona), Spain

^‡ Institut Fresnel, Aix-Marseille Université, CNRS, Domaine Universitaire Saint Jérôme, 13197 Marseille Cedex 20, France

^§ ICREA − Institució Catalana de Recerca i Estudis Avançats, 08010 Barcelona, Spain

Nano Lett., 2012, 12 (4), pp 2107–2111

DOI: 10.1021/nl300389y

Publication Date (Web): March 6, 2012

*E-mail: romain.quidant@icfo.es.

Abstract

Heat is of fundamental importance in many cellular processes such as cell metabolism, cell division and gene expression.(1-3) Accurate and noninvasive monitoring of temperature changes in individual cells could thus help clarify intricate cellular processes and develop new applications in biology and medicine. Here we report the use of green fluorescent proteins (GFP) as thermal nanoprobes suited for intracellular temperature mapping. Temperature probing is achieved by monitoring the fluorescence polarization anisotropy of GFP. The method is tested on GFP-transfected HeLa and U-87 MG cancer cell lines where we monitored the heat delivery by photothermal heating of gold nanorods surrounding the cells. A spatial resolution of 300 nm and a temperature accuracy of about 0.4 °C are achieved. Benefiting from its full compatibility with widely used GFP-transfected cells, this approach provides a noninvasive tool for fundamental and applied research in areas ranging from molecular biology to therapeutic and diagnostic studies.