Lipid Droplet Targeting Type I Photosensitizer for Ferroptosis via Lipid Peroxidation Accumulation.

As an iron-dependent lipid peroxidation (LPO) mediated cell death pathway, ferroptosis offers promises for anti-tumor treatment. Photodynamic therapy (PDT) is an ideal way to generate reactive oxygen species (ROS) for LPO. However, the conventional PDT normally functions on subcellular organelles, such as endoplasmic reticulum (ER), mitochondria (Mito), and lysosome (Lyso), causing rapid cell death before triggering ferroptosis. Herein, we report the first lipid droplet (Ld)-targeting type I photosensitizer (PS) with enhanced superoxide anion (O 2 -· ) production, termed MNBS. The newly designed PS selectively localizes at Ld in cells, and causes cellular LPO accumulation by generating sufficient O 2 -· upon irradiation, and subsequently induces ferroptosis mediated chronical PDT, achieving high-efficient anti-tumor PDT in hypoxia and normoxia. Theoretical calculations and comprehensive characterizations indicate that the Ld targeting property and enhanced O 2 -· generation of MNBS originate from the elevated H-aggregation tendency owing to dispersed molecular electrostatic distribution. Further in vivo studies using MNBS-encapsulated liposomes demonstrated the excellent anti-cancer efficacy as well as anti-metastatic activity. This study offers a paradigm of H-aggregation reinforced type I PS to achieve ferroptosis-mediated PDT. This article is protected by copyright. All rights reserved.