A Phthalocyanine-Based Glutathione-Activated Photosensitizer with a Ferrocenyl Boron Dipyrromethene Dark Quencher for Photodynamic Therapy

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Original languageEnglish
Pages (from-to)1004-1013
Journal / PublicationChemPhotoChem
Issue number10
Online published22 May 2019
Publication statusPublished - Oct 2019


An efficient near‐infrared‐absorbing dark quencher based on ferrocenyl boron dipyrromethene (BODIPY) has been developed and used to construct a fluorescence resonance energy transfer (FRET)‐based activatable photosensitizer. This smart photosensitizer contains a zinc(II) phthalocyanine as the photosensitizing unit which is conjugated to this dark quencher through a glutathione‐cleavable disulfide linker. The photoactivities of the phthalocyanine unit are largely quenched through FRET to the BODIPY unit followed by photoinduced electron transfer from the attached ferrocenyl moiety. Upon exposure to glutathione in phosphate buffered saline and inside HT29 human colorectal adenocarcinoma cells, the fluorescence emission and singlet oxygen generation efficiency of the photosensitizer are significantly enhanced due to cleavage of the disulfide bond and detachment of the dark quencher from the photosensitizing unit. The activation in fluorescence emission has also been demonstrated in tumor‐bearing nude mice. The glutathione‐responsive behavior has been verified by comparison with the negative results of a non‐cleavable analogue. The results suggest that ferrocenyl BODIPYs could serve as tailorable dark quenchers and the disulfide‐linked phthalocyanine–quencher conjugate acts as an efficient glutathione‐activated photosensitizer for photodynamic therapy.photosensitizer for photodynamic therapy.

Research Area(s)

  • boron dipyrromethene, dark quenchers, glutathione, photodynamic therapy, phthalocyanines, FLUORESCENT-PROBES, FRET, CONJUGATE, DESIGN, SERIES, DYES

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