🌡️ Nanothermometers capable of measuring temperature at the nanoscale

Scientists have just developed a new generation of luminescent nanothermometers capable of measuring temperature at the nanoscale. Based on MOFs (metal-organic frameworks), they can measure temperature values, from cryogenic to ambient, with unmatched precision and sensitivity.

Results, published in JACS, that could find applications in fields as varied as biology, medicine, nanotechnology, or materials science.

There is a strong demand for thermometers that can very precisely measure temperatures at the nanoscale and easily integrate into the samples to be measured. In biomedicine, they could for example allow temperature measurement inside cells or tissues, paving the way for more precise diagnostics or better control of hyperthermia therapies. In microelectronics, they could help detect hot spots in integrated circuits, thereby improving the reliability of electronic devices, to name just these two examples.

To perform these measurements, luminescent materials based on lanthanides, metal-organic frameworks (MOFs), capable of emitting light whose intensity or color varies depending on temperature, are highly promising as nanothermometers. Until now, these systems required high concentrations of luminescent lanthanides, leading to concentration quenching and limiting their sensitivity.

The new thermometers proposed by scientists from the Molecular Biophysics Center (CNRS) and Aristotle University of Thessaloniki in Greece, as part of an international collaboration, use MOFs, crystalline materials made of metal ions connected by organic ligands. These structures, known for their porosity and high modularity, were designed here to incorporate luminescent lanthanide ions in a controlled manner. Thanks to this innovative approach, scientists have succeeded in creating ratiometric nanothermometers with concentrations of luminescent elements up to 10 times lower than current systems, while preserving their optical properties.

These MOFs operate over a wide temperature range from cryogenic temperatures (between 10 and 110 kelvins) to room temperature (330 kelvins). They offer detection sensitivities comparable to the highest values reported in the literature.

Even better, while the majority of current nanothermometers are based on europium and terbium, these new systems for the first time use the luminescence of samarium or dysprosium. The use of these new elements expands the possibilities for fine-tuning the luminous properties of the materials, allowing for better adaptation of their response to specific needs.

Finally, the possibility of precisely controlling the doping rate of different lanthanides allows fine-tuning of the color of the luminescence emitted by these materials. This control could prove valuable for applications in nanoscale thermal imaging or for integrating these sensors into complex devices.

Editor: CCdM