Receptor-mediated delivery of photoprotective agents by low-density lipoprotein.

Low density lipoprotein (LDL) has been used to deliver toxic molecules to cells by receptor-mediated endocytosis. In these studies, the cholesteryl ester core of LDL was replaced with a lipophilic, toxic molecule. We now report that photoprotective azo dyes can be stably incorporated into LDL, and that this reconstituted LDL protects cells from the photosensitizing action of pyrene methanol (PM) in a receptor-dependent process. The photoprotective action of the azo dye is due to its ability to scavenge singlet oxygen that is produced by the photosensitive agent in response to UV light.