Polymeric Nanoparticles with Embedded Eu(III) Complexes as Molecular Probes for Temperature Sensing.

Area of Science:

• Coordination Chemistry
• Materials Science
• Biophotonics

Background:

• Accurate intracellular temperature monitoring is crucial for understanding biological processes.
• Existing temperature probes often suffer from photobleaching, low sensitivity, or cytotoxicity.
• Europium(III) complexes offer potential for luminescent sensing due to their unique photophysical properties.

Purpose of the Study:

• To synthesize and characterize novel luminescent Europium(III) complexes for temperature sensing applications.
• To embed these complexes into biocompatible nanoparticles to enhance stability and performance in biological media.
• To evaluate the suitability of these nanoparticle-based probes for intracellular temperature measurements.

Main Methods:

• Synthesis and characterization of three novel Europium(III) complexes (Eu1-Eu3) using CHN analysis, mass spectrometry, and 1H NMR.
• Encapsulation of Eu(III) complexes into biocompatible latex nanoparticles (NPs_Eu1-Eu3).
• Photophysical characterization including emission spectra, quantum yield, excited-state lifetimes, and temperature sensitivity.
• In vitro studies involving cytotoxicity, cellular uptake, and localization in CHO-K1 cells.
• Development of a luminescence lifetime-based temperature calibration curve in various aqueous solutions and biological media.
• Application of the probe for temperature estimation in living cells using time-resolved luminescence imaging (PLIM).

Main Results:

• The synthesized Eu(III) complexes exhibited strong luminescence with high quantum yields and long excited-state lifetimes.
• Embedding the complexes into nanoparticles (NPs_Eu1-Eu3) prevented emission quenching and maintained their photophysical properties.
• The nanoparticle probes demonstrated excellent temperature sensitivity and stability in physiological conditions and biological samples.
• Successful intracellular temperature mapping was achieved in CHO-K1 cells, including monitoring temperature changes during chemical stress.

Conclusions:

• Novel luminescent Eu(III) complexes encapsulated in nanoparticles serve as effective and stable probes for biological temperature sensing.
• The developed probes exhibit good biocompatibility, cellular internalization, and accurate temperature estimation capabilities in living cells.
• This platform holds promise for advancing non-invasive, real-time temperature monitoring in biological systems.