Engineering cellulose acetate fabrics loaded with photosensitizer and graphene oxide endowed with bactericidal activity

Composite materials based on cellulose acetate matrices and porphyrinic photosensitizer (PS) dyes were prepared, characterized and tested as devices with antibacterial activity. Scope of the work is to use light to enable phototoxic bactericidal activity mediated by the production of reactive oxygen species, triggering oxidative damage to pathogens. The materials were fabricated as porous membranes by phase inversion process. Photosensitizers were loaded into the cellulose acetate fabrics as pre-loading, dissolving the dye into the polymer solution before membrane preparation. Different PS loading amounts were explored. We further prepared the fabrics also in the presence of a surfactant or graphene oxide (GO), the latter added to impart mechanical robustness to the final material. We will present the results of the morphological study of the prepared fabrics investigated by scanning electron microscopy and atomic force microscopy. We will further discuss the detailed photophysical characterization of the PS on the fabrics with and without GO performed for the composite materials by means of bulk and spatially resolved techniques. In particular absorption and time-resolved fluorescence data were collected evidencing high PS concentrations caused fluorescence lifetime shortening. Similar effects were observed in the presence of the surfactant. Confocal time-resolved fluorescence lifetime imaging (Figure 1) of the PSloaded fabrics confirmed aggregation phenomena at the basis of the short lifetimes. The most promising fabrics obtained loading the PS in different amounts were used to study the bactericidal effect of the fabrics on S. Aureus bacterial population illuminated with red light.