Quantification of singlet oxygen generation from photodynamic hydrogels

Abstract

Recently, we described a series of novel porphyrin-impregnated hydrogels capable of producing microbicidal singlet oxygen ( 1 O2) on photoactivation. Indirect assessment of the efficacy of 1 O2 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 1 O2, causing photobleaching of its absorbance band at approximately 378 nm. Here, the reaction of this probe is exploited in a novel way to provide a simple, inexpensive, and convenient measurement of . This work demonstrates a simple and straightforward method for direct 1 O2 quantification from porous materials, with general utility.

Effect of Toxic Metal Ions on Photosensitized Singlet Oxygen Generation for Photodegradation of Polyaromatic Hydrocarbon Derivatives and Inactivation of Escherichia coli

“…Upon illumination of the ADPA and TMPyP solution with visible light, a decrease in the absorbance of ADPA absorptions was observed with a red shift (~ 20 nm) of Soret band of TMPyP, indicating some type of electrostatic interaction between negative charge carboxylate functional groups of ADPA and positive charge pyridinium ion of TMPyP increasing the delocalization of π electrons. Similar Soret band shift of TMPyP was observed in presence of TMPyP and reported in the literature . The mechanism of photodegradation of ADPA with singlet oxygen is shown in Scheme .…”

“…Similar Soret band shift of TMPyP was observed in presence of TMPyP and reported in the literature . The mechanism of photodegradation of ADPA with singlet oxygen is shown in Scheme . Singlet oxygen generated from the photosensitization reaction of TMPyP and dissolved oxygen reacted rapidly and irreversibly with ADPA to form an endoperoxide product .…”

Optimization of singlet oxygen production from photosensitizer‐incorporated, medically relevant hydrogels

“…The rate of ADPA uptake into the porous copolymer, where observed, was characterized from the slope of these plots by subtracting the rate of reduction in absorbance of ADPA in the dark from the rate of reduction in absorbance of ADPA in the light. 14…”

“…It is known that this is due to absorption of ADPA into the hydrogel. 14 The rate of production of 1 O 2 was obtained from plots of ADPA absorbance values at 378 nm, in the form of ln (A/A 0 ) against time, where A is absorbance at time t and A 0 is absorbance at time 0. Uptake of ADPA in the copolymer, where observed, was accounted for by subtraction of the rate of reduction in absorbance in the dark from the rate of reduction of absorbance in the light, giving a true rate of production of 1 O 2 .…”

Procesos de oxidación avanzada en el ciclo integral del agua

“…Otra matriz neutra empleada para encapsular fotosensibilizadores ha sido el poli(metacrilato de hidroxietilo) o phemA dado que se trata de un polímero de gran compatibilidad con agua (Craig, 2015). Los hidrogeles de phemA descritos son capaces de unirse a la porfirina de modo no covalente y producir eficientemente oxígeno singlete y oxidar el sustrato AdpA, si bien todavía no se han empleado en una aplicación ambiental.…”