Constructing lipid droplet-targeting photosensitizers based on coumarins with NIR emission.

[Display omitted] • Two lipid-droplets (LDs) targeting photosensitizers (C-S-2 and C-S-3) were designed and synthesized. • C-S-2 and C-S-3 presented NIR emission and singlet oxygen generation capability under laser irradiation. • C-S-3 processed better photostability, superior LDs targeting capability and stronger photodynamic effect than C-S-2. The development of photosensitizers (PSs) with subcellular targeting capability has raised interest for photodynamic therapy (PDT) research. In this work, two coumarin-based photosensitizers (C-S-2 and C-S-3) were designed and synthesized via expanding their π-conjugation, introducing strong electron-donor and acceptor groups, and adopting sulfur substitution strategy. These sulfured-coumarins exhibited near-infrared emission (greater than 650 nm), lipid droplet-targeting ability and obvious photocytotoxicity under laser irradiation. In particular, C-S-3 exhibited better photostability, superior lipid droplet-targeting capability, and stronger photodynamic effect on cancer cells than C-S-2. [ABSTRACT FROM AUTHOR]