Kanazawa University NanoLSI Podcast: Heat and manipulate, one cell at a time

Kanazawa University NanoLSI Podcast: Heat and manipulate, one cell at a time

Transcript of this podcast

Hello and welcome to the NanoLSI podcast. Thank you for joining us today. In this episode we feature the latest research by Satoshi Arai and his co-researchers at the Kanazawa University NanoLSI. 

The research described in this podcast was published in the journal ACS Nano, in June 2022

Learn more about their research here: WPI Kanazawa Nano Life Science Institute

https://nanolsi.kanazawa-u.ac.jp/en/research/researchers/

Original article 

Ferdinandus, Madoka Suzuki, Cong Quang Vu, Yoshie Harada, Satya Ranjan Sarker, Shin’ichi Ishiwata, Tetsuya Kitaguchi, and Satoshi Arai.  Modulation of Local Cellular Activities using a Photothermal Dye-Based Subcellular-Sized Heat Spot, ACS Nano 16, 9004–9018 (2022).

DOI: 10.1021/acsnano.2c00285

URL: https://pubs.acs.org/doi/10.1021/acsnano.2c00285

Heat and manipulate, one cell at a time

Researchers at NanoLSI at Kanazawa University report in ACS Nano the development of a nanoparticle that acts as both a heater and a thermometer.  

Inserting the nanoparticle in living cells results in a heat spot that, by switching it on and off, enables the controlled modulation of local cellular activities.

Being able to heat nano-sized regions in biological tissues is key for several biomedical applications.  Indeed, many biological processes are temperature-sensitive, and the ability to locally modify temperature provides a way to manipulate cellular activity.  

A notable application is the destruction of cancer cells by heating them.  In addition to the need for an in-tissue local heating mechanism, it also important to be able to instantaneously measure the generated temperature.  

Satoshi Arai from NanoLSI at Kanazawa University and colleagues have now engineered a nanoparticle that is both a nanoheater and a nanothermometer at the same time.  They successfully showed that the insertion of a single, controllable heat spot in tissue can be very effective in modifying cellular function.

The nanoparticle, called “nanoHT” by the scientists — an abbreviation of “nanoheater-thermometer” — is essentially a polymer matrix embedding a dye molecule used for sensing temperature, and another dye molecule  for releasing heat.  

The latter happens through the conversion of light into thermal energy. That is, shining a near-infrared laser (with a wavelength of 808 nanometer) onto heat-releasing dye molecule results in fast heating, with a stronger increase in temperature for higher laser power.

Temperature sensing is based on the thermal fluorescence effect of the dye molecule used for sensing temperature.  When irradiated with light of one wavelength, the molecule emits light at another wavelength — fluorescence.  

The higher the temperature, the less intense the fluorescence becomes.  This inverse relationship can be used to measure temperature.  Arai and colleagues tested the performance of nanoHT as a thermometer, and established that it can determine temperatures with a resolution of 0.8 °C and less.

The researchers then performed experiments with human cells called HeLa cells.  They looked at the effect of heating through nanoHT, and found that at a temperature increment of about 11.4 °C, the heated HeLa cells died within a few seconds.  This finding suggests that nanoHT could be used to induce cell death in cancer cells.

Arai and colleagues also studied how nanoHT can be used to affect the behavior of muscles.  They introduced the nanoparticle into myotube, a type of fiber present in muscle tissue.  Up

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