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Rare-earth-doped upconversion nano-phosphor shows new possibilities in the field of bioimaging because of its unique properties like higher penetration depth, low signal to noise ratio ( SNR), good photo stability, and zero auto fluorescence. The oxyfluoride glass system is the combination of both fluoride and oxide where fluoride host offers high optical transparency due to low phonon energy and oxide network offers high physical stability. Thus, in the present work, an attempt has been made to synthesize 1 mol% Er3+ doped SiO2-CaF2 glass ceramic nano-particles through sol-gel route. The synthesized glass ceramic particles were heat treated at 4 different temperatures starting from 600°C to 900°C.The X-ray diffraction ( XRD) analysis and Transmission electron microscopy ( TEM) analysis confirmed the formation of CaF2 nano-crystals in the matrix which is 20-30 nm in size. The vibrational spectroscopic analysis of the glass ceramics sample has been investigated by Fourier transform infrared ( FTIR) spectroscopy. The UV-Visible- NIR spectroscopy analysis was carried out to analyze the absorption intensity in the near infrared region. Upon 980 nm excitation, the sample shows red emission corresponds to 4F9/2→4I15/2 energy level transition. The prepared nano-particles showed excellent biocompatibility when tasted on MG-63 osteoblast cells. [ABSTRACT FROM AUTHOR]

Prokaryotic deacetylases are classified into nicotinamide adenine dinucleotide (NAD + )-dependent sirtuins and Zn 2+ -dependent deacetylases. NAD + is a coenzyme for redox reactions, thus serving as an essential component for energy metabolism. The NAD + -dependent deacetylase domain is quite conserved and well characterized across bacterial species like CobB in Escherichia coli and Salmonella , Rv1151c in Mycobacterium , and SirtN in Bacillus subtilis . E. coli CobB is the only bacterial deacetylase with a known crystal structure (PDB ID: 1S5P), which has 91% sequence similarity with Salmonella CobB (SeCobB). Salmonella encodes two CobB isoforms, SeCobB S and SeCobB L , with a difference of 37 amino acids in its N-terminal domain (NTD). The hydrophobic nature of NTD leads to the stable oligomerization of SeCobB L . The homology modeling-based predicted structure of SeCobB showed the presence of a zinc-binding motif of unknown function. Tryptophan fluorescence quenching induced by ZnCl 2 showed that Zn 2+ has a weak interaction with SeCobB S but higher binding affinity toward SeCobB L , which clearly demonstrated the crucial role of NTD in Zn 2+ binding. In the presence of Zn 2+ , both isoforms had significantly reduced thermal stability, and a greater effect was observed on SeCobB L . Dynamic light scattering (DLS) studies reflected a ninefold increase in the scattering intensity of SeCobB L upon ZnCl 2 addition in contrast to an ∼onefold change in the case of SeCobB S , indicating that the Zn 2+ interaction leads to the formation of large particles of SeCobB L . An in vitro lysine deacetylase assay showed that SeCobB deacetylated mammalian histones, which can be inhibited in the presence of 0.25-1.00 mM ZnCl 2 . Taken together, our data conclusively showed that Zn 2+ strongly binds to SeCobB L through the NTD that drastically alters its stability, oligomeric status, and enzymatic activity in vitro ., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Beura, Pritam, Dhal, Jana, Dash, Mohanty, Panda and Modak.)