Abstract
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. Here we demonstrate a new approach to nanoscale thermometry that uses coherent manipulation of the electronic spin associated with nitrogen-vacancy colour centres in diamond. Our technique makes it possible to detect temperature variations as small as 1.8 mK (a sensitivity of 9 mK Hz(-1/2)) in an ultrapure bulk diamond sample. Using nitrogen-vacancy centres in diamond nanocrystals (nanodiamonds), we directly measure the local thermal environment on length scales as short as 200 nanometres. Finally, by introducing both nanodiamonds and gold nanoparticles into a single human embryonic fibroblast, we demonstrate temperature-gradient control and mapping at the subcellular level, enabling unique potential applications in life sciences.
Highlights
We demonstrate a new approach to nanoscale thermometry that uses coherent manipulation of the electronic spin associated with nitrogen–vacancy colour centres in diamond
Our new approach to nanoscale thermometry uses the quantum mechanical spin associated with nitrogen– vacancy colour centres in diamond
The operational principle of nitrogen–vacancy-based thermometry relies on the accurate measurement of this transition frequency, which can be optically detected with high spatial resolution (Fig. 1)
Summary
LETTER RESEARCH (D) between the jms 5 0æ and jms 5 61æ states (ms, spin projection) has a temperature dependence (dD/dT 5 22p 3 77 kHz K21) due to thermally induced lattice strains[16,17,18]. By recording the temperature of six nanodiamonds at different distances from the laser-heated gold nanoparticle we find that the measured temperature profile (Fig. 3d, points) is in excellent agreement with the theoretical steady-state prediction (solid line) This allows us directly to estimate the temperature change at the location of the gold nanoparticle to be 72 6 6 K. We heat the cell with 12 mW of laser power and measure a temperature change of 0.5 6 0.2 K at the nanodiamond location; this corresponds to a change of approximately 10 K at the position of the gold nanoparticle At this point, the cell is still alive, as confirmed by the absence of ethidium homodimer-1 fluorescence inside the membrane (Fig. 4d). This proof-of-principle experiment indicates that y (μm) ΔT (K)
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