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- Porphyrin (2)
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Organisationseinheit der BAM
The antimicrobial photodynamic approach has been demonstrated as an efficient and sustainable process for the eradication of microbial pathogens. In this work, silica-coated Magnetite nanoparticles (NPs) were used as carriers of glycosylated porphyrins and phthalocyanines. Their subsequent cationization
resulted in the production of stable antimicrobial photosensitizing materials, effective against E. coli. Suspensions of the photocatalysts in water present bimodal size distributions formed by big clusters and small NPs with hydrodynamic diameters between 8 and 38 nm. The presence of small NPs in the suspensions is related to an effective photodynamic inactivation (PDI) of E. coli cells. Glycosylation of the PS showed a positive effect on the PDI performance, which could be related to a higher accumulation of the photocatalyst over the bacterial cell membrane. In addition, these biocidal agents proved to be photostable and their photoactive performance decreased only between 23% and 28% upon 5 PDI cycles, mostly because of the loss of material between cycles, which makes them promising materials for water disinfection purposes.
The preparation of porphyrins and phthalocyanines covalently attached onto nanostructured magnetic supports consisting of magnetite nanoparticles coated with an amorphous silica shell is reported. The easy recovery of these heterogeneous photocatalysts, just by applying an external magnetic field, allows their reuse in multiple treatment cycles. The photocatalytic activity of the non-immobilized photosensitizers and the obtained hybrid materials was evaluated in the degradation of 17 beta-estradiol, as a model organic pollutant present in water, using batch and flow mode treatment systems, assisted by visible light radiation (4 mW cm(-2)). The flow mode system potentiated the photocatalytic capacity of these novel hybrid materials. In order to improve the process, further studies based on different photocatalyst concentration and pH conditions were performed. Reuse capacity of these materials was investigated upon three photocatalytic cycles.