Near‐Infrared Hypocrellin Derivatives for Synergistic Photodynamic and Photothermal Therapy

Hypocrellin B (HB) derived from naturally produced hypocrellins has attracted considerable attention in photodynamic therapy (PDT) because of its excellent photosensitive properties. However, the weak absorption within a “phototherapy window” (600–900 nm) and poor water solubility of HB have limited its clinical application. In this study, two HB derivatives (i. e., HE and HF ) were designed and synthesized for the first time by introducing two different substituent groups into the HB structure. The obtained derivatives showed a broad absorption band covering the near‐infrared (NIR) region, NIR emission (peaked at 805 nm), and singlet oxygen quantum yields of 0.27/0.31. HE‐PEG‐NPs were also prepared using 2‐distearoyl‐sn‐glycero‐3‐phosphoethanolamine‐N‐[methoxy(polyethyleneglycol)‐2000] (DSPE‐mPEG2000) to achieve excellent dispersion in water and further explored their practical applications. HE‐PEG‐NPs not only retained their 1 O 2 ‐generating ability, but also exhibited a photothermal conversion efficiency of 25.9%. In vitro and in vivo therapeutic results revealed that the synergetic effect of HE‐PEG‐NPs on PDT and photothermal therapy (PTT) could achieve a good performance. Therefore, HE‐PEG‐NPs could be regarded as a promising phototheranostic agent.