A carnitine-based BODIPY photosensitizer

Area of Science:

• Biochemistry
• Organic Chemistry
• Cancer Research

Background:

• Organelle-selective photodynamic therapy (PDT) offers enhanced precision in cancer treatment.
• Targeting specific organelles like mitochondria can improve therapeutic outcomes.
• Previous work established mitochondria-targeting probes utilizing carnitine transport.

Purpose of the Study:

• To design and characterize a novel carnitine-based BODIPY photosensitizer (probe 1) for organelle-selective PDT.
• To evaluate probe 1's dual functionality as a fluorescent probe and a photosensitizer.
• To assess probe 1's phototoxicity and targeting capabilities in cancer cells.

Main Methods:

• Synthesis of a novel carnitine-based BODIPY photosensitizer (probe 1).
• Incorporation of bromine atoms to enhance intersystem crossing and singlet oxygen generation.
• Theoretical calculations to understand structure-property relationships.
• Cellular uptake, co-localization studies (mitochondria and lysosomes), and phototoxicity assays under normoxia and hypoxia.

Main Results:

• Probe 1 exhibits mitochondrial selectivity, with dual co-localization in lysosomes.
• Bromine incorporation enhances singlet oxygen quantum yield (∼80%) and phototoxicity.
• High phototoxicity observed with low IC50 values (52 nm normoxia, 117 nm hypoxia) upon green light irradiation.
• Probe 1 is non-cytotoxic in the dark.

Conclusions:

• Probe 1 is a potent, dual-targeting photosensitizer with retained fluorescence.
• Its carnitine-based design facilitates mitochondrial uptake.
• Dual organelle targeting may enhance photodynamic efficacy, particularly in hypoxic tumor microenvironments.