Metal Modulation: An Easy-to-Implement Tactic for Tuning Lanthanide Phototheranostics.

Area of Science:

• Materials Science
• Nanotechnology
• Biomedical Engineering

Background:

• Phototheranostics integrate cancer diagnosis and therapy using photosensitizers (PS).
• Tuning PS photophysical properties is crucial for optimizing phototheranostic efficacy.
• Structural modification of organic frameworks is a key strategy for PS property tuning.

Purpose of the Study:

• To explore a metal selection approach for fine-tuning PS excited-state energy dissipation and phototheranostic functions.
• To develop a lanthanide-containing porphyrinoid complex for combined photoacoustic imaging and photothermal/photodynamic therapy.
• To create a biocompatible nanoparticle construct for enhanced therapeutic delivery and efficacy.

Main Methods:

• Synthesis and characterization of lanthanide (Gd, Yb, Er) carbazole-containing porphyrinoid complexes.
• Femto- and nanosecond time-resolved spectroscopic studies.
• Density functional theory (DFT) calculations.
• Encapsulation of the Yb complex into mesoporous silica nanoparticles (MSN).
• In vitro and in vivo studies using mouse models.

Main Results:

• Metal selection significantly influences excited-state energy dissipation pathways in PSs.
• The Yb complex demonstrated a balanced deactivation mechanism suitable for combined photoacoustic imaging and therapy.
• The YbL@MSN construct exhibited high photothermal conversion efficiency (45%) and singlet oxygen quantum yield (31%).
• YbL@MSN facilitated in vivo photoacoustic imaging and synergistic tumor reduction in mouse models.

Conclusions:

• Metal selection is a promising strategy for tailoring excited-state properties and functions of phototheranostic agents.
• The developed YbL@MSN nanoparticle offers a versatile platform for multimodal cancer theranostics.
• This approach holds potential for advancing the clinical application of phototheranostics.