Luminescent cell-penetrating pentadecanuclear lanthanide clusters.

Area of Science:

• Inorganic Chemistry
• Materials Science
• Biomedical Applications

Background:

• Lanthanide clusters are of interest for their unique magnetic and luminescent properties.
• Developing new ligands is crucial for stabilizing and functionalizing these clusters.
• Peptoids offer a versatile platform for designing functional ligands.

Purpose of the Study:

• To synthesize and characterize a novel pentadecanuclear lanthanide hydroxy cluster using peptoid ligands.
• To investigate the structural integrity of the cluster in solution.
• To evaluate the luminescent properties and in vitro biological activity of the synthesized clusters.

Main Methods:

• Single-crystal X-ray crystallography for solid-state structure determination.
• Electrospray Ionization Mass Spectrometry (ESI-MS) for solution studies.
• Confocal microscopy (TRLLM mode) for cellular uptake studies.
• In vitro cytotoxicity assays with HeLa tumor cells.

Main Results:

• A novel pentadecanuclear lanthanide hydroxy cluster [{Ln15(μ3-OH)20(PepCO2)10(DBM)10Cl}Cl4] was successfully prepared and characterized.
• The cluster core remained intact in solution as evidenced by ESI-MS.
• Europium-based cluster (1) exhibited intense red fluorescence (11% quantum yield), while the Terbium-based cluster (2) showed weaker emission.
• Clusters accumulated in the endosomal-lysosomal system of HeLa cells.
• Both clusters displayed moderate cytotoxicity against HeLa tumor cells.

Conclusions:

• The successful incorporation of peptoids as supporting ligands in lanthanide hydroxy clusters opens new avenues for functional materials.
• The luminescent properties and cellular uptake mechanisms suggest potential applications in bioimaging.
• The moderate cytotoxicity warrants further investigation for therapeutic applications.