Synthesis of Siliconized Photosensitizers for Use in 1O2-Generating Silicone Elastomers: An Electron Paramagnetic Resonance Study

Biomedical devices based on silicone are essential tools in modern healthcare but can be compromised by the development of device-acquired infections (DAIs). Unfortunately, the continued rise of antibiotic-resistant organisms makes current strategies to combat DAIs insufficient. Recently, the use of photoactive coatings that produce reactive oxygen species, specifically singlet oxygen (1O2), has attracted attention as a potential alternative to traditional strategies to prevent DAIs. However, the synthesis and characterization of silicone devices capable of 1O2 production are not trivial. Development is hindered by the incompatibility of photosensitizers with the silicone matrix and an incomplete understanding of how the method of incorporation impacts 1O2 production. Using the Piers–Rubinsztajn reaction, the photosensitizer 5,10,15,20-(tetra-3-methoxyphenyl)porphyrin (TPMP) was derivatized to be compatible with silicone matrices without the assistance of solvents and could be incorporated either covalently or physically within silicone elastomers. Electron paramagnetic resonance measurements indicated that 1O2 was more efficiently generated from elastomers containing a covalently cross-linked TPMP derivative than their physically dispersed counterparts, due to the minimization of aggregates.