19-Jan-2021 - Osaka University

Nanodiamonds feel the heat

Nanodiamond sensor can act as both heat sources and thermometers, and may lead to a new set of heat-based treatments for killing bacteria or cancer cells

A team of scientists from Osaka University, The University of Queensland, and the National University of Singapore's Faculty of Engineering used tiny nanodiamonds coated with a heat-releasing polymer to probe the thermal properties of cells. When irradiated with light from a laser, the sensors acted both as heaters and thermometers, allowing the thermal conductivity of the interior of a cell to be calculated. This work may lead to a new set of heat-based treatments for killing bacteria or cancer cells.

Even though the cell is the fundamental unit of all living organisms, some physical properties have remained difficult to study in vivo. For example, a cell's thermal conductivity, as well as the rate that heat can flow through an object if one side is hot while the other side is cold, remained mysterious. This gap in our knowledge is important for applications such as developing thermal therapies that target cancer cells, and for answering fundamental questions about cell operation.

Now, the team has developed a technique that can determine the thermal conductivity inside living cells with a spatial resolution of about 200 nm. They created tiny diamonds coated with a polymer, polydopamine, that emit both fluorescent light as well as heat when illuminated by a laser. Experiments showed that such particles are non-toxic and can be used in living cells. When inside a liquid or a cell, the heat raises the temperature of the nanodiamond. In media with high thermal conductivities, the nanodiamond did not get very hot because heat escaped quickly, but in an environment of low thermal conductivity, the nanodiamonds became hotter. Crucially, the properties of the emitted light depend on the temperature, so the research team could calculate the rate of heat flow from the sensor to the surroundings.

Having good spatial resolution allowed measurements in different locations inside the cells. "We found that the rate of heat diffusion in cells, as measured by the hybrid nanosensors, was several times slower than in pure water, a fascinating result which still waits for a comprehensive theoretical explanation and was dependent on the location," senior author Taras Plakhotnik says.

"In addition to improving heat-based treatments for cancer, we think potential applications for this work will result in a better understanding of metabolic disorders, such as obesity," senior author Madoka Suzuki says. This tool may also be used for basic cell research, for example, to monitor biochemical reactions in real time.

Facts, background information, dossiers
  • thermal conductivity
  • cancer
  • nanosensors
More about Osaka University
  • News

    Sorting out viruses with machine learning

    The ongoing global pandemic has created an urgent need for rapid tests that can diagnose the presence of the SARS-CoV-2 virus, the pathogen that causes COVID-19, and distinguish it from other respiratory viruses. Now, researchers from Japan have demonstrated a new system for single-virion i ... more

    Good vibrations: Using piezoelectricity to ensure hydrogen sensor sensitivity

    A team at Osaka University has invented a new process for creating high-precision sensing devices that respond to the presence of hydrogen gas. By carefully controlling the deposition of metallic nanoparticles on a silicon surface, the researchers were able to create a sensor that can detec ... more

    Rolling the dice on perovskite interfaces

    Perovskites are a type of mineral and class of materials, and have been attracting a great deal of attention for their potential applications to technologies such as those used in solar cells. These unique materials have well-ordered structures and show many interesting properties that coul ... more

More about University of Queensland
  • News

    Stem cell identity unmasked by single cell sequencing technology

    Scientists from The University of Queensland's Diamantina Institute have revealed the difference between a stem cell and other blood vessel cells using gene-sequencing technology. Leading skin cancer and stem cell researcher Professor Kiarash Khosrotehrani said the findings provided evidenc ... more

    Next-gen steel under the microscope

    Next-generation steel and metal alloys are a step closer to reality, thanks to an international research project involving a University of Queensland scientist. The work could overcome the problem of hydrogen alloy embrittlement that has led to catastrophic failures in major engineering and ... more

    Tunable plastic thermometers

    Researchers at the Universities of Queensland and New South Wales in Australia have discovered that the ability of a plastic to conduct electricity can be tuned by exposure to an ion beam. Usually plastics conduct electricity so poorly that they are used as the insulation around electrical ... more

More about National University of Singapore
  • News

    New insights into promising semiconductor material

    Researchers from the National University of Singapore (NUS) have established new findings on the properties of two-dimensional molybdenum disulfide (MoS2), a widely studied semiconductor of the future. In two separate studies led by Professor Andrew Wee and Assistant Professor Andrivo Rusyd ... more

    How the liver unclogs itself

    A multi-disciplinary team of researchers from the Mechanobiology Institute, Singapore (MBI) at the National University of Singapore (NUS), the Institute of Bioengineering and Nanotechnology (IBN) of A*STAR, and BioSyM, Singapore-MIT Alliance for Research and Technology have described the me ... more

    Illuminating the contacts

    The development of super resolution microscopy has revolutionised how scientists view and understand the inner workings of the cell. Just as advances in satellite camera technology gave rise to highly detailed maps of the world, so too has super-resolution microscopy allowed researchers to ... more