Ln(III) Complexes Embedded in Biocompatible PLGA Nanoparticles as Potential Vis-to-NIR Optical Probes

Area of Science:

• Coordination Chemistry
• Materials Science
• Biomedical Optics

Background:

• Hydrophobic lanthanide (Ln(III)) complexes often require specialized environments for stability and application.
• Near-infrared (NIR) emitting probes are valuable for bioimaging due to reduced tissue autofluorescence and deeper penetration.
• Visible light sensitization offers a safer alternative to UV excitation for biological applications.

Purpose of the Study:

• To spectroscopically characterize two novel heteroleptic NIR emitting complexes, (R,R)-YbL1(tta) and (R,R)-NdL1(tta).
• To investigate the feasibility of embedding these complexes into poly lactic-co-glycolic acid (PLGA) nanoparticles for enhanced stability and biocompatibility.
• To evaluate their potential as optical probes for bioimaging applications, focusing on sensitization and cytotoxicity.

Main Methods:

• Synthesis and spectroscopic analysis (UV-Vis absorption, luminescence) of Yb(III) and Nd(III) complexes.
• Encapsulation of the complexes within poly lactic-co-glycolic acid (PLGA) nanoparticles.
• Cytotoxicity assays on two distinct cell lines to assess biocompatibility.

Main Results:

• The hydrophobic heteroleptic complexes, (R,R)-YbL1(tta) and (R,R)-NdL1(tta), exhibit NIR emission.
• Visible light sensitization of the complexes' emission was achieved due to their broad absorption spectra.
• Encapsulation in PLGA nanoparticles rendered the complexes water-dispersible and stable, with no significant observed cytotoxicity.

Conclusions:

• The developed Yb(III) and Nd(III) complexes can be effectively sensitized by visible light, offering a safer excitation method.
• PLGA nanoparticle encapsulation provides a viable strategy for stabilizing these hydrophobic complexes in aqueous environments.
• These nanoparticle-encapsulated complexes demonstrate potential as biocompatible optical probes for future bioimaging applications.