NGC 4102: High Resolution Infrared Observations of a Nuclear Starburst Ring

The composite galaxy NGC 4102 hosts a LINER nucleus and a starburst. We mapped NGC 4102 in the 12.8 micron line of [NeII], using the echelon spectrometer TEXES on the NASA IRTF, to obtain a data cube with 1.5" spatial and 25 km/s spectral, resolution. Combining near-infrared, radio, and the [NeII] data shows that the extinction to the starburst is substantial, more than 2 magnitudes at K band, and that the neon abundance is less than half solar. We find that the star formation in the nuclear region is confined to a rotating ring or disk of 4.3" (~300 pc) diameter, inside the Inner Lindblad Resonance. This region is an intense concentration of mass, with a dynamical mass of ~3 x 10^9 solar masses, and of star formation. The young stars in the ring produce the [NeII] flux reported by Spitzer for the entire galaxy. The mysterious blue component of line emission detected in the near-infrared is also seen in [NeII]; it is not a normal AGN outflow.Comment: submitted to Ap

Bioactivity of biosilica obtained from North Atlantic deep-sea sponges

Demosponges are a well-known source of a plethora of bioactive compounds. In particular, they are able to form a skeleton by direct deposition of silica in a process catalysed by silicatein. Herein, we isolated biosilicas from five different Atlantic deep-sea sponges Geodia atlantica (GA), Geodia barretti (GB), Stelletta normani (SN), Axinella infundibuliformis (AI) and Phakellia ventilabrum (PV) to explore the bioactivity and osteogenic capacity of its silica-based materials. We chemically characterized the isolated biosilicas and evaluated them for their bioactivity to deposit Ca and P on their surface (by immersion in simulated body fluid, SBF). GB-, SN-, AI- and PV-based biosilicas did not generate a stable calcium phosphate (CaP) layer over time in the presence of SBF, however, the GA-derived one was able to form a CaP surface layer (at a Ca/P ratio of ~1.7, similar to the one observed for hydroxyapatite), that was stable during the 28 days of testing. In addition, no cytotoxicity towards L929 and SaOs2 cells was observed for the GA-based biosilica up to a concentration of 10 mg/mL. Overall, the GA-based biosilica presents the characteristics to be used in the development of biomaterials for bone tissue engineering (BTE).This research has been performed with funding from the European Union’s Horizon 2020 research and innovation programme under Grant Agreements No. 679849 (SponGES) and No. 668983 (FORECAST). Funding from the European Regional Development Fund, through Atlantic Area Program, under the scope of BlueHuman project (EAPA_151/2016) is also acknowledged. JRX research was also supported by National Funds through FCT, the Portuguese Foundation for Science and Technology within the scope of UIDB/04423/2020, UIDP/04423/2020, and CEECIND/00577/2018

Fucoidan-coated silica nanoparticles promote the differentiation of human mesenchymal stem cells into the osteogenic lineage

Silica nanoparticles (SiNPs) are widely used in biomedical applications, such as cancer therapy/diagnosis or tissue engineering and regenerative medicine. Herein, we synthesized SiNPs and modified them with sulfonic acid groups (by organosilylation followed by oxidation) or a sulfated polysaccharide (i.e., fucoidan, a seaweed biopolymer, by using electrostatic surface immobilization) due to the known capacity of the sulfonic/sulfate moieties to stabilize proteins and promote stem cell differentiation toward the osteogenic lineage. The developed pristine and functionalized nanoparticles were characterized by dynamic light scattering (DLS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS), showing the monodisperse size distribution (between 360 and 450 nm) and the success of the coating/functionalization with fucoidan or sulfonic groups. The developed SiNPs (at a concentration of 50 μg/mL) were assessed through their contact with SaOs2 cells evidencing their cytocompatibility. Furthermore, the osteogenic differentiation of bmMSCs was evaluated by the quantification of ALP activity, as well as the expression profile of osteogenic-related genes, such as Runx2, ALP, and OP. We found that the coating of the SiNPs with fucoidan induced the osteogenic differentiation of bmMSCs, being an effective mediator of bone regeneration.FCT -Fundação para a Ciência e a Tecnologia(679849

Bioactivity of Biosilica Obtained From North Atlantic Deep-Sea Sponges

Demosponges are a well-known source of a plethora of bioactive compounds. In particular, they are able to form a skeleton by direct deposition of silica in a process catalyzed by silicatein. Herein, we isolated biosilicas from five different Atlantic deep-sea sponges Geodia atlantica (GA), Geodia barretti (GB), Stelletta normani (SN), Axinella infundibuliformis (AI), and Phakellia ventilabrum (PV) to explore the bioactivity and osteogenic capacity of its silica-based materials. We chemically characterized the isolated biosilicas and evaluated them for their bioactivity to deposit Ca and P on their surface (by immersion in simulated body fluid, SBF). GB-, SN-, AI-, and PV-based biosilicas did not generate a stable calcium phosphate (CaP) layer over time in the presence of SBF, however, the GA-derived one was able to form a CaP surface layer (at a Ca/P ratio of ∼1.7, similar to the one observed for hydroxyapatite), that was stable during the 28 days of testing. In addition, no cytotoxicity toward L929 and SaOs2 cells was observed for the GA-based biosilica up to a concentration of 10 mg/mL. Overall, the GA-based biosilica presents the characteristics to be used in the development of biomaterials for bone tissue engineering (BTE)