Facile one-step solvothermal synthesis of a luminescent europium metal-organic framework for rapid and selective sensing of uranyl ions

A simple, cost-effective, and portable uranium sensory material with adequate selectivity is increasingly urgent and would be of great importance in environmental monitoring of radionuclides. Herein, we report a novel luminescent europium metal-organic framework (Eu-MOF) with plenty of Lewis basic sites for binding uranyl ions (UO2 (2+)), the most common form of uranium in solution, through a facile one-step solvothermal synthetic route. The mesoporous structure consists of europium nodes and flexible nitrogen-containing ligands with a 29.2 x 20.5 (2) channel along the c-axis. Furthermore, the obtained material displays characteristic fluorescence of trivalent Eu3+ and could be applied as a turn-off sensory probe targeting UO2 (2+) in solution. Differential fluorescent quenching occurred upon a series of potential interfering ions compared to UO2 (2+) and the detection limit as low as 0.9 mu M was achieved with a rapid response

Novel Bioactive Peptides from <i>Meretrix meretrix</i> Protect <i>Caenorhabditis elegans</i> against Free Radical-Induced Oxidative Stress through the Stress Response Factor DAF-16/FOXO

The hard clam Meretrix meretrix, which has been traditionally used as medicine and seafood, was used in this study to isolate antioxidant peptides. First, a peptide-rich extract was tested for its protective effect against paraquat-induced oxidative stress using the nematode model Caenorhabditis elegans. Then, three novel antioxidant peptides; MmP4 (LSDRLEETGGASS), MmP11 (KEGCREPETEKGHR) and MmP19 (IVTNWDDMEK), were identified and were found to increase the resistance of nematodes against paraquat. Circular dichroism spectroscopy revealed that MmP4 was predominantly in beta-sheet conformation, while MmP11 and MmP19 were primarily in random coil conformation. Using transgenic nematode models, the peptides were shown to promote nuclear translocation of the DAF-16/FOXO transcription factor, a pivotal regulator of stress response and lifespan, and induce the expression of superoxide dismutase 3 (SOD-3), an antioxidant enzyme. Analysis of DAF-16 target genes by real-time PCR reveals that sod-3 was up-regulated by MmP4, MmP11 and MmP19 while ctl-1 and ctl-2 were also up-regulated by MmP4. Further examination of daf-16 using RNA interference suggests that the peptide-increased resistance of C. elegans to oxidative stress was DAF-16 dependent. Taken together, these data demonstrate the antioxidant activity of M. meretrix peptides, which are associated with activation of the stress response factor DAF-16 and regulation of the antioxidant enzyme genes

Physicochemical Characterization and Functional Analysis of the Polysaccharide from the Edible Microalga Nostoc sphaeroides

Nostoc colonies have been used as food and medicine for centuries, and their main supporting matrix is polysaccharides, which help Nostoc cells resist various environmental stresses including oxidative stress. Here we isolated a polysaccharide, nostoglycan, from cultured Nostoc sphaeroides colonies and determined its physicochemical properties, which revealed a characteristic infrared absorption spectrum typical of polysaccharides and an amorphous morphology with rough surfaces. We also show that nostoglycan has strong moisture absorption and retention capacities and a high relative viscosity. Using Caenorhabditis elegans models, we then demonstrate that nostoglycan is capable of improving overall survival rate of the animals under increased oxidative stress caused by paraquat. Nostoglycan also reduces reactive oxygen species level, inhibits protein carbonyl formation and lipid peroxidation, and increases activities of superoxide dismutase and catalase in paraquat-exposed nematodes. As oxidative stress may drive tumor progression, we further demonstrate that nostoglycan can suppress the proliferation of several types of tumor cells and induce apoptosis of human lung adenocarcinoma A549 cells via caspase-3 activation. Together, our results yield important information on the physicochemical characteristics and demonstrate the antioxidant and anti-proliferative functions of nostoglycan, and thus provide an insight into its potential in food and health industries