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Research
Thermochromic Detection of Ultrasound-Induced Nanoparticle Heating in Tissue-Mimicking Solid Gel
Nelson Gee-Con Chen
National Chiao Tung University
Corresponding Author
ORCiD: https://orcid.org/0000-0002-9843-2922
License:
This work is licensed under a CC BY 4.0 License. Read Full License
Background
Microbubble has been extensively used for ultrasound imaging and many other applications such as ultrasound cleaning. Few studies have been reported on ultrasound interactions with small nanoparticles (< 250 nm). Due to the broad use of nanoparticles in many different fields, it is critically important to clarify whether nanoparticles can have strong interaction with ultrasound. In addition, Nanoparticle assisted ultrasound therapy has recently been found to have selective killing of cancer cells compared to normal cells. Nevertheless, the mechanism is not known. The major possible mechanisms for killing cells are cavitation and heating. In this work, a simple thermochromic method is developed to clearly indicate that the interaction of nanoparticle with ultrasound can lead to temperature rise that can lead to selective killing of cancer cells.
Results
Direct three-dimensional detection of ultrasonically induced heating in a nanoparticle bearing tissue-mimicking gel would provide a means to estimate their effectiveness as thermally-based sonosensitizers. Such a gel was produced through the addition of an irreversible thermochromic liquid to a well-known agarose gel during fabrication. Polystyrene nanoparticles were embedded within gels during production. The placement of gels within a temperature-controlled bath set to a temperature below the transition temperature allows for the visual detection of slight temperature increases. The modified gel material was shown to undergo color change upon heating to 54 °C from blue to white. The appearance of white color on the gel is a clear indication of nanoparticle to enhance the ultrasound energy to increase the temperature of gel. Nanoparticle presence within a solid causing increased heating upon ultrasound exposure, as detected through thermochromicity, is reported for the first time.
Conclusion
Even small nanoparticles can have significant interaction with ultrasound to lead to temperature rise in the medium. Therefore, the selective killing of cancer cells more than normal cell should be primarily from heating instead of cavitation since cancer cells in general cannot survive in higher temperature than normal cells. Cavitation should lead to the killing of both cancer and normal cells due to the release of a large amount of energy in the process. Direct three-dimensional detection of ultrasonically induced heating in a nanoparticle bearing tissue-mimicking gel becomes feasible.
Keywords
nanoparticle, temperature sensor, ultrasound heating
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This is a preprint. It has not completed peer review.
Research
Thermochromic Detection of Ultrasound-Induced Nanoparticle Heating in Tissue-Mimicking Solid Gel
Nelson Gee-Con Chen
National Chiao Tung University
Corresponding Author
ORCiD: https://orcid.org/0000-0002-9843-2922
Badges
Prescreen
This manuscript passed our Prescreen assessment
Complete author information
Appropriate declaration statements
Potential risks to human health
Prescreen
History
CURRENT STATUS: Posted
Version 1
Posted 19 May, 2020
No community comments so far
Metrics
Comments: 0
PDF Downloads: ...
HTML Views: ...
Subject Areas
Nanoscience
License:
This work is licensed under a CC BY 4.0 License. Read Full License
Background
Microbubble has been extensively used for ultrasound imaging and many other applications such as ultrasound cleaning. Few studies have been reported on ultrasound interactions with small nanoparticles (< 250 nm). Due to the broad use of nanoparticles in many different fields, it is critically important to clarify whether nanoparticles can have strong interaction with ultrasound. In addition, Nanoparticle assisted ultrasound therapy has recently been found to have selective killing of cancer cells compared to normal cells. Nevertheless, the mechanism is not known. The major possible mechanisms for killing cells are cavitation and heating. In this work, a simple thermochromic method is developed to clearly indicate that the interaction of nanoparticle with ultrasound can lead to temperature rise that can lead to selective killing of cancer cells.
Results
Direct three-dimensional detection of ultrasonically induced heating in a nanoparticle bearing tissue-mimicking gel would provide a means to estimate their effectiveness as thermally-based sonosensitizers. Such a gel was produced through the addition of an irreversible thermochromic liquid to a well-known agarose gel during fabrication. Polystyrene nanoparticles were embedded within gels during production. The placement of gels within a temperature-controlled bath set to a temperature below the transition temperature allows for the visual detection of slight temperature increases. The modified gel material was shown to undergo color change upon heating to 54 °C from blue to white. The appearance of white color on the gel is a clear indication of nanoparticle to enhance the ultrasound energy to increase the temperature of gel. Nanoparticle presence within a solid causing increased heating upon ultrasound exposure, as detected through thermochromicity, is reported for the first time.
Conclusion
Even small nanoparticles can have significant interaction with ultrasound to lead to temperature rise in the medium. Therefore, the selective killing of cancer cells more than normal cell should be primarily from heating instead of cavitation since cancer cells in general cannot survive in higher temperature than normal cells. Cavitation should lead to the killing of both cancer and normal cells due to the release of a large amount of energy in the process. Direct three-dimensional detection of ultrasonically induced heating in a nanoparticle bearing tissue-mimicking gel becomes feasible.
Figure 1
Figure 2
Figure 3
Figure 4