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: An optical fiber has been developed with a maneuverable miniprobe tip that sparges O2 gas and photodetaches pheophorbide (sensitizer) molecules. Singlet oxygen is produced at the probe tip surface which reacts with an alkene spacer group releasing sensitizer upon fragmentation of a dioxetane intermediate. Optimal sensitizer photorelease occurred when the probe tip was loaded with 60 nmol sensitizer, where crowding of the pheophorbide molecules and self-quenching were kept to a minimum. The fiber optic tip delivered pheophorbide molecules and singlet oxygen to discrete locations. The 60 nmol sensitizer was delivered into petrolatum; however, sensitizer release was less efficient in toluene-d8 (3.6 nmol) where most had remained adsorbed on the probe tip, even after the covalent alkene spacer bond had been broken. The results open the door to a new area of fiber optic-guided sensitizer delivery for the potential photodynamic therapy of hypoxic structures requiring cytotoxic control.


"Reprinted (adapted) with permission from Matibur Zamadar; Goutam Ghosh; Adaickapillai Mahendran; Mihaela Minnis; Bonnie Kruft; Ashwini Ghogare; David Aebisher; Alexander Greer “Photosensitizer Drug Delivery via an Optical Fiber” J. Am. Chem. Soc. 2011, 133, 7882-7891. Copyright (2011) American Chemical Society."



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