That’s hot: molecular thermometer determines temperature within cells
A novel molecular thermometer based on solvatochromic dyes can determine temperature fluctuations within cells.
Measuring your temperature is as simple as sticking a thermometer in your mouth, but for cells, it’s not that easy. Now, researchers from the Institute of Science Tokyo (Japan) have developed a molecular thermometer with novel solvatochromic dyes that change color in response to environmental temperature changes. This technique offers unparalleled spatial resolution and a non-invasive approach, setting it apart from traditional methods.
Temperature plays a vital role in biological processes at the cellular level, influencing everything from enzymatic reactions to metabolic activity. However, accurately measuring temperature within living cells remains challenging, with traditional techniques lacking the spatial resolution required to detect subtle temperature variations within cells.
To overcome this, the team developed a molecular thermometer using novel fluorescent dyes that change their fluorescence properties in response to environmental polarity shifts. As temperature increases, there is a slight decrease in the polarity of the environment, causing the dyes to emit light at different wavelengths and intensities. By measuring the ratios of fluorescence intensities at two specific wavelengths, the researchers could accurately determine temperature changes.
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The newly developed dyes demonstrated exceptional ‘solvatochromic’ properties – when a molecule changes color as the solvent polarity changes – with shifts in the wavelengths emitted from the dyes exceeding 200 nm between different solvents. The researchers could perform temperature measurements with a relative sensitivity of up to 3.0%/°C and a resolution of less than 0.1 °C.
The researchers tested their molecular thermometer by introducing one of the dyes into living human cell cultures. Using ratiometric confocal microscopy, they confirmed that the dye responds to temperature changes within cellular environments, particularly in cellular droplets, where local temperature variations may play crucial roles in biological processes.
“This molecular thermometer based on a solvatochromic fluorescent dye is expected to greatly expand the scope of fluorescence thermometry and contribute to uncovering unknown biological phenomena due to its superior spatial resolution, non-invasiveness, and ease of molecular design,” explained corresponding author Gen-ichi Konishi.
By providing unprecedented insights into temperature fluctuations within cells, these novel dyes may help scientists uncover temperature-dependent biological processes. Next, the researchers plan to develop a library of solvatochromic fluorescence thermometers to cover a diverse range of environments.
