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Fluorescent Thermometers Based on Carbon Quantum Dots with Various Detection Modes for Intracellular Temperature
Yuki S Kato1, Yukiho Shimazaki2,3, Shunsuke Chuma3
1Department of Biological Sciences, School of Science, The University of Osaka, Machikaneyamacho Toyonaka, Osaka 560-0043, Japan.
Nano Letters
|March 26, 2025
Summary
We developed carbon quantum dots (CQDs) for precise nanoscale temperature sensing in live cells. These CQDs offer versatile detection modes, including fluorescence lifetime, enabling accurate cellular thermometry.
Area of Science:
- Materials Science
- Nanotechnology
- Biomedical Engineering
Background:
- Accurate nanoscale temperature measurement is crucial for understanding cellular processes.
- Existing thermometry methods face limitations in sensitivity, invasiveness, and applicability within live cells.
- Carbon quantum dots (CQDs) offer unique optical properties for potential biosensing applications.
Purpose of the Study:
- To synthesize and characterize versatile carbon quantum dots (CQDs) for nanoscale thermometry.
- To investigate the use of CQDs as fluorescent nanothermometers with multiple detection modes.
- To demonstrate the application of CQDs for precise, minimally invasive temperature measurements in live cells.
Main Methods:
- Hydrothermal synthesis of CQDs using anthraquinone derivatives and l-cysteine.
- Modification of CQD precursors to enable fluorescence intensity, ratiometric, and fluorescence lifetime-based thermometry.
- In vitro and in vivo evaluation of CQD cytotoxicity, cellular uptake, and temperature sensing capabilities.
- Measurement of temperature changes during biochemical reactions and cellular events.
Main Results:
- Synthesized CQDs exhibited versatile detection modes for fluorescence-based thermometry.
- Fluorescence lifetime-based CQDs showed robust performance across varying pH and ionic strength.
- CQDs demonstrated low cytotoxicity and high cellular uptake, enabling wash-free imaging.
- Precise single-cell temperature measurements were achieved using fluorescence lifetime, cross-verified by fluorescence intensity.
- Temperature changes associated with mitochondrial depolarization were successfully quantified.
Conclusions:
- CQDs are versatile and effective tools for nanoscale thermometry in live cells.
- Fluorescence lifetime-based thermometry with CQDs offers robust and precise temperature measurements.
- CQDs provide a minimally invasive approach for studying cellular thermal dynamics.
- These findings highlight the potential of CQDs in advancing cellular imaging and diagnostics.
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