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Nanometer-scale Thermometry in a Living Cell
Sensitive probing of temperature variations on nanometre scales is an outstanding challenge in many areas of modern science and technology. In particular, a thermometer capable of subdegree temperature resolution over a large range of temperatures as well as integration within a living system could provide a powerful new tool in many areas of biological, physical and chemical research. Possibilities range from the temperature-induced control of gene expression and tumour metabolism to the cell-selective treatment of disease and the study of heat dissipation in integrated circuits. By combining local light-induced heat sources with sensitive nanoscale thermometry, it may also be possible to engineer biological processes at the subcellular level. We demonstrated an approach to nanoscale thermometry that used coherent manipulation of the electronic spin associated with nitrogen–vacancy colour centres in diamond. Our technique made it possible to detect temperature variations as small as 1.8mK(a sensitivity of 9mKHz-1/2) in an ultrapure bulk diamond sample. Through use of nitrogen–vacancy centres in diamond nanocrystals (nanodiamonds), we directly measured the local thermal environment on length scales as short as 200 nanometres. Finally, through the introduction of both nanodiamonds and gold nanoparticles into a single human embryonic fibroblast, we demonstrated temperature-gradient control and mapping at the subcellular level, which enabled unique potential applications in life sciences.