Emodin‐Based Nanoarchitectonics with Giant Two‐Photon Absorption for Enhanced Photodynamic Therapy

Abstract Two‐photon‐excited photodynamic therapy (TPE‐PDT) has significant advantages over conventional photodynamic therapy (PDT). However, obtaining easily accessible TPE photosensitizers (PSs) with high efficiency remains a challenge. Herein, we demonstrate that emodin (Emo), a natural anthraquinone (NA) derivative, is a promising TPE PS with a large two‐photon absorption cross‐section (TPAC: 380.9 GM) and high singlet oxygen ( 1 O 2 ) quantum yield (31.9 %). When co‐assembled with human serum albumin (HSA), the formed Emo/HSA nanoparticles (E/H NPs) possess a giant TPAC (4.02×10 7 GM) and desirable 1 O 2 generation capability, thus showing outstanding TPE‐PDT properties against cancer cells. In vivo experiments reveal that E/H NPs exhibit improved retention time in tumors and can ablate tumors at an ultra‐low dosage (0.2 mg/kg) under an 800 nm femtosecond pulsed laser irradiation. This work is beneficial for the use of natural extracts NAs for high‐efficiency TPE‐PDT.