Synthesis and characterization of photoactive porphyrin and poly(2-hydroxyethyl methacrylate) based materials with bactericidal properties

Abstract Poly(2-hydroxyethyl methacrylate)-based materials bearing porphyrinic units were prepared, characterized and their ability to inactivate Escherichia coli and Staphylococcus aureus bacteria was evaluated. Porphyrins containing methacrylate moieties were prepared by the sequential nucleophilic substitution of the para-fluorine atoms in 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin (P1) with 2-hydroxyethyl methacrylate (HEMA). Two distinct materials were obtained, namely PHEMA-Porph by in situ non-covalent incorporation of P1 (porphyrin with no methacrylic unit) during the free radical polymerization of HEMA, and PHEMA-co-Porph by the covalent coupling of P2 (porphyrin containing one methacrylic unit) with HEMA via free radical polymerization. Both PHEMA-co-Porph and PHEMA-Porph showed to be fluorescent and photostable under visible light and to have the capacity to generate singlet oxygen. The evaluation of the photodynamic inactivation (PDI) exhibited by the two photoactive materials towards the selected bacteria showed that, apart from the higher performance of PHEMA-co-Porph, both can be reused at least three times without significant loss of their efficacy towards E. coli. In this sense, these photoactive polymeric materials bearing porphyrinic units have potential as photosensitizers for photodynamic inactivation of both Gram-positive and Gram-negative bacteria.