Synthesis of a poly(ethylene glycol) galloyl sensitizer tip for an ’all‐in‐one' photodynamic device

Abstract

This paper describes the synthesis of a specialized silica tip for an optical fiber device capable of delivering all components necessary for photodynamic therapy. Oxygen, light and a cleavable tripolyethylene glycol (PEG)-galloyl pheophorbide sensitizer are simultaneously delivered by the silica tip, where the tip was synthesized in six steps. A comparison of synthetic steps to reach PEGylated sensitizers bound to fluorinated silica and a previously reported Teflon/polyvinyl alcohol (PVA) nanocomposite ( Ghosh, G. et al. J. Phys. Chem. B 2015, 119, 4155- 4164) was made. The hydrolytic stability of the attached PEGs and the extent to which the PEG groups enhance solubility will also be discussed. The new triPEG-galloyl sensitizer has the potential for use in intraoperative pointsource photodynamic therapy which aims for precision treatment of residual disease. Schematic of the synthesis of a photoactive silica surface. It is composed of fluorinated silica connected to a photo-releasable sensitizer with short-chain PEGs.

Synthesis, Photophysics and PDT Evaluation of Mono‐, Di‐, Tri‐ and Hexa‐PEG Chlorins for Pointsource Photodynamic Therapy

“…Two of the sensitizers (2 and 3) are new, and their synthesis is described here. The synthesis of the other four sensitizers (1,(4)(5)(6) has been reported previously (4,5). Our synthesis led to 1 in 40%, 2 in 51%, 3 in 52%, 4 in 50%, 5 in 48% and 6 in 33% overall yields.…”

“…Synthesis of triPEG galloyl pheophorbide acid (1). Compound 1 was synthesized from triPEG galloyl 7 and pyropheophorbide-a methylester in 2 steps as reported in literature (5). Briefly, pyropheophorbide-a methylester was reacted with 30% HBr/AcOH (1.0 mL) followed by reaction galloyl-triPEG 7 and K 2 CO 3 in anhydrous dichloromethane to form triPEG galloyl pheophorbide methylester.…”