Homogeneous Luminescence Detection Based on Lanthanide Coordination Compound.

Area of Science:

• Coordination Chemistry
• Luminescence Spectroscopy
• Biomedical Sensing

Background:

• Lanthanide coordination compounds (LnCC) are effective luminophores for detection but typically require heterogeneous systems due to water's luminescence quenching effect.
• Heterogeneous systems limit sensor stability, sensitivity, selectivity, and complicate mechanistic studies.

Purpose of the Study:

• To develop homogeneous luminescence detection techniques using LnCC.
• To investigate the chemical mechanisms underlying homogeneous LnCC-based sensing.
• To create a water-soluble, highly luminescent LnCC for sensitive and selective biomedical detection.

Main Methods:

• Synthesis of a water-soluble europium dipicolinic acid (Eu-DPA) coordination compound using multifaceted sonication.
• Characterization of Eu-DPA's luminescence properties (quantum efficiency, lifetime).
• Application of Eu-DPA for detecting 5-hydroxyindoleacetic acid (5-HIAA) in aqueous solutions, plasma, and urine using luminescence spectroscopy.
• Mechanistic investigation using Transient Absorption Spectroscopy (TAS) and Time-Resolved Luminescence Spectroscopy (TRES).

Main Results:

• The synthesized Eu-DPA exhibited excellent water solubility (140.3 mg/g) and luminescence (92.49% quantum efficiency, >2 ms lifetime).
• The homogeneous sensor demonstrated high sensitivity, selectivity, and stability in detecting 5-HIAA across different biological matrices.
• Spectroscopic analyses confirmed hydrogen bonding and electrostatic interactions between Eu-DPA and 5-HIAA, influencing energy transfer and luminescence.

Conclusions:

• Homogeneous LnCC sensors can overcome water-induced luminescence quenching, offering advantages over traditional heterogeneous systems.
• Eu-DPA serves as a practical and effective homogeneous luminescent detector for the carcinoid marker 5-HIAA.
• This research provides a foundation for developing advanced, water-compatible luminescence-based biomedical sensors.