Transition metals (TM) are essential microelements with various biological functions demanded in tissue regeneration applications. Little is known about therapeutic potential of TM within soft hydrogel biomaterials. The soluble TM, such as Zn, Cu, Mn and Co, were stably incorporated into gelatin network during cryogelation. TM content in the resultant cryogels varied from 0.1×10 3 to 11.8×10 3 ppm, depending on the initial TM type and concentration in reaction solution. Zn was uniformly complexed with the gelatin scaffold according to elemental imaging, increasing the swelling of polymer walls and the G'/G'' values and also decreasing the size of cryogel macro-pores Zn-doped cryogels supported migration of human skin fibroblasts (HSF); only upper Zn content of 11.8×10 3 ppm in the scaffold caused c.a. 50% inhibition of cell growth. Zn ions solubilized in culture medium were more active towards HSF (IC50 ≈ 0.3 mM). Treatment of splinted full-skin excisional wounds in rats with the Zn-doped and non-doped cryogels showed that Zn considerably promotes d passing inflammatory/proliferation phases of healing process, inducing more intense dermis formation and structuration. The results show the feasibility of development of cryogel based formulations with different TM and support high phase-specific ability of the Zn-gelatin cryogels to repair acute wounds.

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Trophic niche and diet comparisons among closely sympatric marine species are important to understand complex food webs, particularly in regions most affected by climate change. Using stable isotope analyses, all ontogenetic stages of three sympatric species of Arctic cephalopods (genus Rossia) were studied to assess inter- and intraspecific competition with niche and diet overlap and partitioning in West Greenland and the Barents Sea. Seven traits related to resource and habitat utilization were identified in Rossia: no trait was shared by all three species. High boreal R. megaptera and Arctic endemic R. moelleri shared three traits with each other, while both R. megaptera and R. moelleri shared only two unique traits each with widespread boreal-Arctic R. palpebrosa. Thus all traits formed fully uncrossing pattern with each species having unique strategy of resource and habitat utilization. Predicted climate changes in the Arctic would have an impact on competition among Rossia with one potential ‘winner’ (R. megaptera in the Barents Sea) but no potential ‘losers’.

Despite enormous interest toward graphene oxide (GO) from the research community, surprisingly, little is known about its solutions. In particular, the questions related to the structure of the GO/liquid interface have not been yet properly addressed. In this report, we use a simple but efficient experimental approach to investigate the distribution of the four metal cations Na+, Cs+, Ni2+, and Gd3+ at the GO/water interface. We demonstrate that the concentration of the cations decreases exponentially with the distance from the GO surface. Such distribution for colloid systems was theoretically predicted and commonly accepted for a century but, to the best of our knowledge, has been never proved experimentally. We further demonstrate that the shape of the counterion distribution profiles depends on the pH of solution and on the fine chemical structure of GO. In particular, organic sulfates and vinylogous acids that are ionizable at different pH levels are responsible for the difference in the shapes of the concentration profiles. Unlike classical colloid systems, the diffuse layer in the GO solutions is rather broad (30–55 nm), and the concentration gradient is registered even at distances of >55 nm from the GO surface, which is typically considered as the bulk solution. The latter observation is explained by the immobilized character of the GO flakes in the nematic phase, impeding the flow of liquid and the migration of hydrated metal cations. This helps to establish and maintain the long-range concentration gradient in the space between the two parallel neighboring GO flakes. Based on the new findings and on the previously reported data, we formulate some basic principles of GO solutions.

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