Synthesis, spectroscopic characterization and singlet oxygen generation of 5,10,15,20-tetrakis(3,5-dimethoxyphenyl) porphyrin as a potential photosensitizer for photodynamic therapy

Singlet oxygen is a valuable reactive oxygen species known for its effective action on the elimination of cancers and age-related eye disease such as macular degeneration. In this study, 5,10,15,20-tetrakis (3,5-dimethoxyphenyl) porphyrin was synthesized and characterized using various spectroscopic methods. The λmax for the Soret and Q bands were 417 nm and 514, 547, 589 and 646 (nm) respectively. The estimated singlet oxygen yield (φΔ) for the porphyrin was higher than some literature reports, suggesting a stronger potential of the porphyrin for the photosensitizing photodynamic treatment of cancer and other related human disorders.

Genetic autonomy and low singlet oxygen yield support kleptoplast functionality in photosynthetic sea slugs

Elysia chlorotica is a kleptoplastic sea slug that preys on Vaucheria litorea, stealing its plastids which then continue to photosynthesize for months inside the animal cells. We investigated the native properties of V. litorea plastids to understand how they withstand the rigors of photosynthesis in isolation. Transcription of specific genes in laboratory-isolated V. litorea plastids was monitored up to seven days. The involvement of plastid-encoded FtsH, a key plastid maintenance protease, in recovery from photoinhibition in V. litorea was estimated in cycloheximide-treated cells. In vitro comparison of V. litorea and spinach thylakoids was applied to investigate ROS formation in V. litorea. Isolating V. litorea plastids triggered upregulation of ftsH and translation elongation factor EF-Tu (tufA). Upregulation of FtsH was also evident in cycloheximide-treated cells during recovery from photoinhibition. Charge recombination in PSII of V. litorea was found to be fine-tuned to produce only small quantities of singlet oxygen (1O2). Our results support the view that the genetic characteristics of the plastids themselves are crucial in creating a photosynthetic sea slug. The plastid’s autonomous repair machinery is likely enhanced by low 1O2 production and by upregulation of FtsH in the plastids.HighlightIsolated Vaucheria litorea plastids exhibit upregulation of tufA and ftsH, key plastid maintenance genes, and produce only little singlet oxygen. These factors likely contribute to plastid longevity in kleptoplastic slugs.

Oxygen yields as a constraint on feedback processes in galaxies

ABSTRACT We study the interplay between several properties determined from optical and a combination of optical/radio measurements, such as the effective oxygen yield (yeff), the star formation efficiency, gas metallicity, depletion time, gas fraction, and baryonic mass (Mbar), among others. We use spectroscopic data from the SDSS survey, and H i information from the ALFALFA survey to build a statistically significant sample of more than 5000 galaxies. Furthermore, we complement our analysis with data from the GASS and COLD GASS surveys, and with a sample of star-forming galaxies from the Virgo cluster. Additionally, we have compared our results with predictions from the EAGLE simulations, finding a very good agreement when using the high-resolution run. We explore in detail the Mbar–yeff relation, finding a bimodal trend that can be separated when the stellar age of galaxies is considered. On one hand, yeff increases with Mbar for young galaxies [log(tr) < 9.2 yr], while yeff shows an anticorrelation with Mbar for older galaxies [log(tr) > 9.4 yr]. While a correlation between Mbar and yeff has been observed and studied before, mainly for samples of dwarfs and irregular galaxies, their anticorrelated counterpart for massive galaxies has not been previously reported. The EAGLE simulations indicate that AGN feedback must have played an important role in their history by quenching their star formation rate, whereas low-mass galaxies would have been affected by a combination of outflows and infall of gas.

Systematic Evaluation of Light-Activatable Biohybrids for Anti-Glioma Photodynamic Therapy

Photosensitizing biomolecules (PSBM) represent a new generation of light-absorbing compounds with improved optical and physicochemical properties for biomedical applications. Despite numerous advances in lipid-, polymer-, and protein-based PSBMs, their effective use requires a fundamental understanding of how macromolecular structure influences the physicochemical and biological properties of the photosensitizer. Here, we prepared and characterized three well-defined PSBMs based on a clinically used photosensitizer, benzoporphyrin derivative (BPD). The PSBMs include 16:0 lysophosphocholine-BPD (16:0 Lyso PC-BPD), distearoyl-phosphoethanolamine-polyethylene-glycol-BPD (DSPE-PEG-BPD), and anti-EGFR cetuximab-BPD (Cet-BPD). In two glioma cell lines, DSPE-PEG-BPD exhibited the highest singlet oxygen yield but was the least phototoxic due to low cellular uptake. The 16:0 Lyso PC-BPD was most efficient in promoting cellular uptake but redirected BPD’s subcellular localization from mitochondria to lysosomes. At 24 h after incubation, proteolyzed Cet-BPD was localized to mitochondria and effectively disrupted the mitochondrial membrane potential upon light activation. Our results revealed the variable trafficking and end effects of PSBMs, providing valuable insights into methods of PSBM evaluation, as well as strategies to select PSBMs based on subcellular targets and cytotoxic mechanisms. We demonstrated that biologically informed combinations of PSBMs to target lysosomes and mitochondria, concurrently, may lead to enhanced therapeutic effects against gliomas.

Enhanced photocatalytic activity of BiVO4 coupled with iron-based complexes for water oxidation under visible light irradiation

Four iron complexes were used as pre-catalysts in BiVO4–NaIO3 photocatalytic water oxidation systems. The best-performing system afforded a rather high oxygen yield and apparent quantum efficiency yield of 99.1% and 44.3%, respectively.

Fine tuning of pyridinium-functionalized dibenzo[a,c]phenazine near-infrared AIE fluorescent biosensors for the detection of lipopolysaccharide, bacterial imaging and photodynamic antibacterial therapy

A series of NIR fluorescent probes of dibenzophenazine pyridine salt with different alkyl chain were developed for the detection of LPS. BD2C with ethyl chain exhibited a significant improvement of the singlet oxygen yield and antibacterial property.