Mitochondria-Targeting Boron Dipyrromethene Based Photosensitizers for Enhanced Photodynamic Therapy: Synthesis,...

Increasing Investigations show that photosensitizers (PSs) which target mitochondria are useful for enhancing photodynamic therapy (PDT) efficacy. Herein, we carefully designed and synthesized four triphenylphosphonium (TPP)-modified boron dipyrromethene (BDP)-based PSs through Cu(I)-assisted "3+2" cycloaddition reaction. All of them exhibit intense red light absorption with maxima between 659 and 663 nm, considerable fluorescence emission with quantum yields of 0.16-0.23, high singlet oxygen generation efficiency ranging from 0.22 to 0.34, excellent mitochondria-targeting ability, and good biocompatibility. Upon illumination, they induce significant cancer cell death through a mitochondria-related apoptosis pathway. The IC₅₀ values of these BDP dyes against MCF-7 cells were determined to be as low as 0.046-0.113 μM under rather low dosage of light irradiation (1.5 J ⋅ cm^-2 ).