Cobalt(II)-coordination polymers containing glutarates and bipyridyl ligands and their antifungal potential.

Three new CoII-coordination polymers (Co-CPs) containing glutarates and bipyridyl ligands, formulated as [Co2(Glu)2(µ-bpa)2]·(H2O)4 (1), [Co4(Glu)4(µ-bpp)2] (2), and [Co2(Glu)2(µ-bpe)2]·(H2O)0.5 (3), were prepared, and their structures were determined by X-ray crystallography. Glutarates bridge CoII ions to form 2D sheets, and the sheets are connected either by bpa or by bpp ligands to form 3D networks 1 and 2, respectively. Both frameworks 1 and 2 are two-fold interpenetrated, and there is no significant void volume in either network. Four glutarates bridge two CoII ions to form chains, and these chains are connected by bpe ligands to form the 2D sheet 3. The antifungal properties of these new Co-CPs were tested against two model fungal pathogens, Candida albicans and Aspergillus niger. Under the maximum concentration of Co-CPs, 2.0 mg mL-1, the inhibition rates of Co-CPs against A. niger were much lower (44-62%) than those (90-99.98%) observed in C. albicans. The results indicate that 1-3 can inactivate C. albicans cells more efficiently than A. niger spores in the same treatment time, and the greater inactivation of C. albicans can be explained by dramatic changes in the morphology of C. albicans cells. We also found that Co-CPs could generate the reactive species NO and H2O2, and these species might play a role in inactivating fungal cells. Additionally, degradation tests confirmed that the leaching of CoII ions from Co-CPs was not significant. The small amount of leached CoII ions and the robust Co-CPs themselves as well as the reactive species generated by Co-CPs can actively participate in fungal inactivation.

Aspergillus oryzae spore germination is enhanced by non-thermal atmospheric pressure plasma.

Poor and unstable culture growth following isolation presents a technical barrier to the efficient application of beneficial microorganisms in the food industry. Non-thermal atmospheric pressure plasma is an effective tool that could overcome this barrier. The objective of this study was to investigate the potential of plasma to enhance spore germination, the initial step in fungal colonization, using Aspergillus oryzae, a beneficial filamentous fungus used in the fermentation industry. Treating fungal spores in background solutions of phosphate buffered saline (PBS) and potato dextrose broth (PDB) with micro dielectric barrier discharge plasma using nitrogen gas for 2 and 5 min, respectively, significantly increased the germination percentage. Spore swelling, the first step in germination, was accelerated following plasma treatment, indicating that plasma may be involved in loosening the spore surface. Plasma treatment depolarized spore membranes, elevated intracellular Ca2+ levels, and activated mpkA, a MAP kinase, and the transcription of several germination-associated genes. Our results suggest that plasma enhances fungal spore germination by stimulating spore swelling, depolarizing the cell membrane, and activating calcium and MAPK signaling.

Cold atmospheric plasma (CAP), a novel physicochemical source, induces neural differentiation through cross-talk between the specific RONS cascade and Trk/Ras/ERK signaling pathway.

Plasma, formed by ionization of gas molecules or atoms, is the most abundant form of matter and consists of highly reactive physicochemical species. In the physics and chemistry fields, plasma has been extensively studied; however, the exact action mechanisms of plasma on biological systems, including cells and humans, are not well known. Recent evidence suggests that cold atmospheric plasma (CAP), which refers to plasma used in the biomedical field, may regulate diverse cellular processes, including neural differentiation. However, the mechanism by which these physicochemical signals, elicited by reactive oxygen and nitrogen species (RONS), are transmitted to biological system remains elusive. In this study, we elucidated the physicochemical and biological (PCB) connection between the CAP cascade and Trk/Ras/ERK signaling pathway, which resulted in neural differentiation. Excited atomic oxygen in the plasma phase led to the formation of RONS in the PCB network, which then interacted with reactive atoms in the extracellular liquid phase to form nitric oxide (NO). Production of large amounts of superoxide radical (O2-) in the mitochondria of cells exposed to CAP demonstrated that extracellular NO induced the reversible inhibition of mitochondrial complex IV. We also demonstrated that cytosolic hydrogen peroxide, formed by O2- dismutation, act as an intracellular messenger to specifically activate the Trk/Ras/ERK signaling pathway. This study is the first to elucidate the mechanism linking physicochemical signals from the CAP cascade to the intracellular neural differentiation signaling pathway, providing physical, chemical and biological insights into the development of therapeutic techniques to treat neurological diseases.