Silica Gel–Supported P-, Ge-, and Sb-Porphyrins for Visible Light Inactivation of Bacteria

This chapter describes the photocatalysis action of (dihydroxo)tetraphenyl¬porphyrinato complexes of high valent P (V), Ge (IV), and Sb (V) (P(tpp), Ge(tpp), and Sb(tpp)). These chromophores were fixed onto silica gel (SiO2) through Coulombic forces and hydrogen bonding between axial hydroxo ligands and silanol groups to produce M(tpp)/SiO2 (M = P, Ge, and Sb) composites. M(tpp)/SiO2 were applied to the photo-inactivation of Escherichia coli and Legionella pneumophila. Moreover, M(tpp)/SiO2 was subjected to practical experiments for the photoinactivation of L. pneumophila naturally occurring in a cooling tower and a public fountain. It is noteworthy that 80 g of Sb(tpp)/SiO2 catalyst, containing 40 mg of Sb(tpp) maintained a concentration of Legionella species below 100 CFU/100 mL for 120 days in 13 m3 of water in a fountain under sunlight exposure. The photoinactivation proceeded through the liberation of M(tpp) from SiO2, adsorption of M(tpp) inside bacteria, and generation of reactive oxygen species, such as singlet oxygen, under visible light irradiation, thus resulting in bacteria apoptosis. Based on these results, we developed water-soluble porphyrins by modification of P and Sb porphyrin axial ligands to alkyloxo, alkylethylenedioxy, and alkylpyridinium groups. These water-soluble porphyrins were applied to the photodynamic inactivation of E. coli and Saccharomyces cerevisiae

Photodynamic Inactivation of <em>Escherichia coli</em> with Cationic Porphyrin Sensitizers

The activity of singlet-oxygen sensitizers for photodynamic inactivation (PDI) of microorganisms and photodynamic therapy of tumor cells has been evaluated using Escherichia coli, Saccharomyces cerevisiae, and human cancer cell lines. In this chapter, drug resistance of E. coli was examined based on the PDI activity of a variety of RPy-P-porphyrin sensitizers with different number of ionic valence and different hydrophobic characters. The PDI activities toward E. coli were evaluated using the minimum effective concentrations ([P]) of the porphyrin sensitizers. It was found that the [P] value for E. coli was larger than that for S. cerevisiae. E. coli has drug-resistance toward hydrophobic and mono-cationic porphyrins. However, E. coli has weak drug-resistance toward the porphyrins with both polycationic character and hydrophobicity. Since the outer membrane mainly consists of lipopolysaccharides and phospholipids that are negatively charged, cationic porphyrins are able to adsorb to the outer leaflet. Then the cationic porphyrins with hydrophobic character can interact with not only the outer leaflet but also inner leaflet of the outer membrane and the plasma membrane. Thus, porphyrins may be incorporated inside E. coli cells via the self-promoted uptake pathway. Moreover, polycationic porphyrins can interact with DNA and proteins by strong binding affinities

Neutrino-driven massive stellar explosions in 3D fostered by magnetic fields via turbulent α\alpha-effect

We investigate the influence of magnetic field amplification on the core-collapse supernovae in highly magnetized progenitors through three-dimensional simulations. By considering rotating models, we observe a strong correlation between the exponential growth of the magnetic field in the gain region and the initiation of shock revival, with a faster onset compared to the non-rotating model. We highlight that the mean magnetic field experiences exponential amplification as a result of $\alpha$-effect in the dynamo process, which works efficiently with the increasing kinetic helicity of the turbulence within the gain region. Our findings indicate that the significant amplification of the mean magnetic fields leads to the development of locally intense turbulent magnetic fields, particularly in the vicinity of the poles, thereby promoting the revival of the shock by neutrino heating.Comment: 6 pages, 4 figures, submitted to MNRAS Letter