Single-Nanoparticle Luminescence Nanothermometers with Enhanced Sensitivity in Physiological Temperature Range.

Area of Science:

• Materials Science
• Nanotechnology
• Optical Physics

Background:

• Upconverting nanoparticles (UCNPs) offer unique optical properties for sensing applications.
• Luminescence nanothermometers (LNTs) require precise control over optical properties for accurate temperature readings.
• Lanthanide-based UCNPs are promising for thermometry due to their distinct emission spectra.

Purpose of the Study:

• To synthesize and characterize core-shell UCNPs for enhanced luminescence nanothermometer performance.
• To investigate the effect of a NaYF4 shell on luminescence energy loss and temperature sensitivity.
• To optimize LNT sensitivity in the physiological temperature range using surfactants.

Main Methods:

• Synthesis of core (NaYF4:Yb3+,Er3+) and core-shell (NaYF4:Yb3+,Er3+@NaYF4) upconverting nanoparticles (UCNPs).
• Characterization of UCNPs' optical properties and luminescence intensity ratio (IG2/IG1) as a function of temperature.
• Addition of IGEPAL CO-520 surfactant and deionized water to study their impact on LNT sensitivity.

Main Results:

• The NaYF4 shell significantly reduced luminescence energy loss, leading to a steeper temperature vs. luminescence intensity ratio curve.
• Addition of IGEPAL CO-520 surfactant and water further improved LNT sensitivity, particularly between 35-40 °C.
• Surfactant-particle interactions were identified as key to reducing luminescent energy loss and enhancing sensitivity.

Conclusions:

• Core-shell UCNPs with a NaYF4 shell demonstrate superior performance as luminescence nanothermometers.
• Surfactant modification offers a viable strategy to boost LNT sensitivity in physiological temperature ranges.
• The developed lanthanide-based LNTs are suitable for in vitro applications and potential use in microelectronics and environmental monitoring.