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

Photodynamic therapy and photodynamic antimicrobial chemotherapy are widely used, but despite this, the relationships between fluence, wavelength of irradiation and singlet oxygen (¹ O₂ ) production are poorly understood. To establish the relationships between these factors in medically relevant materials, the effect of fluence on ¹ O₂ production from a tetrakis(4-N-methylpyridyl)porphyrin (TMPyP)-incorporated 2-hydroxyethyl methacrylate: methyl methacrylate: methacrylic acid (HEMA: MMA:MAA) copolymer, a total energy of 50.48 J/cm² , was applied at varying illumination power, and times. ¹ O₂ production was characterized using anthracene-9,10-dipropionic acid, disodium salt (ADPA) using a recently described method. Using two light sources, a white LED array and a white halogen source, the LED array was found to produce less ¹ O₂ than the halogen source when the same power (over 500 - 600 nm) and time conditions were applied. Importantly, it showed that the longest wavelength Q band (590 nm) is primarily responsible for ¹ O₂ generation, and that a linear relationship exists between increasing power and time and the production of singlet oxygen. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 320-326, 2017.