Thursday, 1 August 2013

Researchers develop nanodiamond thermometer to take temperature of individual cells

Researchers develop nanodiamond
thermometer to take temperature
of individual cells
The image shows an artistic
representation of a novel technique
for nanoscale temperature control
inside of a living cell using
techniques from quantum optics. The
image depicts a rendering of a cell
containing nanodiamonds and gold
nanoparticles. A gold nanoparticle is
heated by an external laser beam
and nanodiamonds are used to probe
the local temperature. Credit: Georg
( —Researchers working at a
lab at Harvard University have
developed a technique that allows for
taking the temperature of individual
living cells. In their paper published
in the journal Nature , the team
describes their technique and just
how precise temperature
measurements taken with it can be.
The new thermometer developed by
the team follows work by other
researchers who have found that
single atom impurities in diamond
crystals (which typically are replaced
with a nitrogen atom and a vacancy
gap) can be ultrasensitive to changes
in temperature—such fluctuations
can be seen as a hindrance when
attempting to use such material to
hold quantum bits , but in the
biological world , they can be used to
very precisely measure temperature.
In their research the team at Harvard
injected a single nanodiamond (a
diamond just 100 nm in size) into a
human cell. Once in place a green
laser was shone onto the
nanodiamond. Because it altered the
spin state of an electron in the
impurity, the light that was emitted
was changed to red. The degree to
which it was changed was then used
to calculate the temperature of the
interior of the cell. Following that
experiment, the team injected two
nanodiamonds into a single cell, then
focused two separate green lasers
onto them, then measured the red
light that was emitted. This allowed
them to measure the temperature
difference between two locations in
the same cell. Next, the team
injected a nanodiamond and a gold
particle into the cell. Once in place a
green laser was shone onto the
nanodiamond while another laser
was shined onto the gold particle
causing it to heat up. That heat was
transferred to the rest of the cell and
was subsequently measured by the
Using this technique the researchers
report being able to measure
temperature fluctuations as small as
0.05 Kelvin—they expect to achieve
better results in the future as
temperature fluctuations as small as
0.0018 Kelvin have been recorded
using the device outside of a cell. A
thermometer with such precision
could conceivably be used for both
research purposes and in practical
applications such as helping to
distinguish (or kill) individual cancer
cells inside the body.
More information: Nanometre-scale
thermometry in a living cell, Nature
500, 54–58 (01 August 2013)
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 metabolism6
to the cell-selective treatment of
disease7, 8 and the study of heat
dissipation in integrated circuits1. 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.
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