Unveiling Mechanism of Organic Photogenerator for Hydroxyl Radicals Generation by Molecular Modulation

Abstract

Photodynamic therapy (PDT) with organic photosensitizers generally goes through the oxygen‐dependent process, generating singlet oxygen and/or superoxide anion. However, the generation of reactive oxygen species is often suppressed as a result of hypoxia, one of the common features in tumors, therefore limiting the effectiveness of the tumor treatments. Consequently, it is urgent and significant to develop an oxygen‐independent hydroxyl radical photogenerator and unveil the mechanism. In this work, a hydroxyl radical (·OH) photogenerator originating from the electron transfer process is engineered. Detailed mechanism studies reveal that the optimized photosensitizer, WS2D, which contains a bithiophene unit, could both promote charge carrier generation and accelerate reaction efficiency, resulting in the efficient production of ·OH. In addition, WS2D nanoparticles are constructed to improve the polydispersity and stability in aqueous solution, which exhibit excellent biocompatibility and mitochondrial targeting. Bearing the above advantages, WS2D is employed in phototheranostics, which could release ·OH effectively and damage mitochondria precisely, achieving high PDT efficiency in vitro and in vivo. Overall, this work successfully provides valuable insights into the structural design of a hydroxyl radicals (·OH) photogenerator with great practical perspectives.

Integration of TADF Photosensitizer as “Electron Pump” and BSA as “Electron Reservoir” for Boosting Type I Photodynamic Therapy

“…To further clarify the sensitization mechanism, we tested the ROS components generated by the PS/BSA system with the following ROS quenching experiments. Specific ROS scavengers NaN 3 (for 1 O 2 ), vitamin C (for O 2 •– ), and isopropyl alcohol (for OH • ) were separately chosen to quench the single species of ROS. As shown in Figure h, the emission intensity of 2′,7′-dichlorodihydrofluorescein (DCFH) was obviously reduced when treated with vitamin C. It suggests that O 2 •– is the most ROS generated in the PS/BSA system.…”

“…•− ), 11 and isopropyl alcohol (for OH • ) 56 were separately chosen to quench the single species of ROS. As shown in Figure 1h, the emission intensity of 2′,7′-dichlorodihydrofluorescein (DCFH) was obviously reduced when treated with vitamin C. It suggests that O 2…”

Two-photon responsive porphyrinic metal-organic framework involving Fenton-like reaction for enhanced photodynamic and sonodynamic therapy

“…However, it is worth mentioning that these porphyrin derivatives can be employed as sonosensitizers to effectively compensate for the barrier of shallow penetration depth in PDT [19,20]. Notably, the above two cancer treatment methods are highly oxygen dependent, the severe hypoxic environment of tumor greatly limits the corresponding outcome [21][22][23][24]. To face this grand challenge, various solutions have been developed to fabricate new oxygenation nanomaterials [25][26][27].…”

Simultaneous one-step regulation of planarization and donor rotation to enhance multi-modal imaging guided therapy

“…[1][2][3][4] Therein, photodynamic therapy (PDT) induces apoptosis and death of cancer cells by using photosensitizers (PSs), light sources, and reactive oxygen species (ROS) including Type II or Type I. [5][6][7] In detail, the Type II ROS ( 1 O 2 ) is produced through energy transfer, which always depends on the amount of surrounding O 2 , limiting the application to the hypoxic tumor tissues. 8,9 Thus, some Type I PSs producing OH and O 2 À were developed with fewer oxygen-dependent features through adjusting the donor (D)-acceptor (A) to strengthen the electron transfer for treating hypoxic tumors.…”