Proton Tunneling Allows a Proton-Coupled Electron Transfer Process in the Cancer Cell

Tong Zhang, Arindam Ghosh, Lisa Behringer-Pließ, Lata Chouhan, Ana V. Cunha, Remco W.A. Havenith, Eugenia Butkevich, Lei Zhang, Olalla Vázquez, Elke Debroye, Jörg Enderlein*, Shoubhik Das*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Proton-coupled electron transfer (PCET) is a fundamental redox process and has clear advantages in selectively activating challenging C-H bonds in many biological processes. Intrigued by this activation process, we aimed to develop a facile PCET process in cancer cells by modulating proton tunneling. This approach should lead to the design of an alternative photodynamic therapy (PDT) that depletes the mitochondrial electron transport chain (ETC), the key redox regulator in cancer cells under hypoxia. To observe this depletion process in the cancer cell, we monitored the oxidative-stress-induced depolarization of mitochondrial inner membrane potential (MMP) using fluorescence lifetime imaging microscopy (FLIM). Typically, increasing metabolic stress of cancer cells is reflected in a nontrivial change in the fluorophore’s fluorescence lifetime. After 30 min of irradiation, we observed a shift in the mean lifetime value and a drastic drop in overall fluorescence signal. In addition, our PCET strategy resulted in drastic reorganization of mitochondrial morphology from tubular to vesicle-like and causing an overall depletion of intact mitochondria in the hypodermis of C. elegans. These observations confirmed that PCET promoted ROS-induced oxidative stress. Finally, we gained a clear understanding of the proton tunneling effect in the PCET process through photoluminescence experiments and DFT calculations.

Original languageEnglish
Pages (from-to)4856-4865
Number of pages10
JournalJACS Au
Volume4
Issue number12
DOIs
Publication statusPublished - 10-Dec-2024

Keywords

  • proton tunneling
  • proton-coupled electron transfer
  • photodynamic therapy
  • metal free
  • fluorenone derivatives

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