Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5209822 | Reactive and Functional Polymers | 2015 | 6 Pages |
Recently, we described a series of novel porphyrin-impregnated hydrogels capable of producing microbicidal singlet oxygen (1O2) on photoactivation. Indirect assessment of the efficacy of 1O2 production from such hydrogels has been previously described using microbiological techniques, but here we report a novel, direct method of quantification. Anthracene-9,10-dipropionic acid (ADPA) is known to irreversibly form an endoperoxide on reaction with 1O2, causing photobleaching of its absorbance band at approximately 378Â nm. Here, the reaction of this probe is exploited in a novel way to provide a simple, inexpensive, and convenient measurement of 1O2 generation from the surface of porphyrin-incorporated photosensitising hydrogels, with the ability to account for effects due to hydrogel porosity. Ingress of the probe into the materials was observed, with rates of up to 3.83Â ÃÂ 103Â sâ1. This varied by up to 200-fold with material composition and surface modification. Rates of 1O2 generation in these porphyrin-incorporated hydrogels, after compensating for ADPA ingress, ranged from 1.86Â ÃÂ 103 to 5.86Â ÃÂ 103Â sâ1. This work demonstrates a simple and straightforward method for direct 1O2 quantification from porous materials, with general utility.