Synthesis of Schiff Bases Based on Chitosan and Heterocyclic Moiety: Evaluation of Antimicrobial Activity.

Schiff bases of chitosan (CS) were prepared by reaction of four different heterocyclic compounds, namely, 1,3-dimethyl-2,4,6-trioxohexahydropyrimidine-5-carbaldehyde (M1), 3-acetyl-2H-chromen-2-one (M2), 5-chloro-3-methyl-1-phenyl-1H-pyrazole-4-carbaldehyde (M3), and 4-oxo-4H-chromene-3-carbaldehyde (M4), with CS using thermal and ultrasound approaches. CS Schiff base formation was confirmed by using FT-IR, XRD, and TGA. Characteristic data show that amino groups in chitosan reacted with the functional group in the heterocyclic compound to form the Schiff base. CS Schiff bases show thermal stability more than pure CS. The antimicrobial activity of Schiff bases was tested against +ve Gram bacteria and -ve Gram bacteria. The result shows that Schiff bases prepared by temperature and ultrasound methods possess high antimicrobial activity against +ve Gram bacteria and -ve Gram bacteria; in comparison, Schiff bases produced by the ultrasound method have higher antimicrobial activity. The Schiff base (CSM4U), prepared by the ultrasound method by reaction of CS with 4-oxo-4H-chromene-3-carbaldehyde, exhibited higher antimicrobial activity than Gentamicin as an antibacterial agent. The inhibition range caused by CSM4U was between 19 and 27 mm. Moreover, CSM4U also acted as an antifungal agent, causing an inhibition zone of 21 mm for both Candida albicans and Candida tropicalis, which was higher than that of Terbinafine.

State, synthesis, perspective applications, and challenges of Graphdiyne and its analogues: A review of recent research.

Carbon materials technology provides the possibility of synthesizing low-cost, outstanding performance replacements to noble-metal catalysts for long-term use. Graphdiyne (GDY) is a carbon allotrope with an extremely thin atomic thickness. It consists of carbon elements, that are hybridized with both sp. and sp2, resulting in a multilayered two-dimensional (2D) configuration. Several functional models suggest, that GDY contains spontaneously existing band structure with Dirac poles. This is due to the non-uniform interaction among carbon atoms, which results from various fusions and overlapping of the 2pz subshell. Unlike other carbon allotropes, GDY has Dirac cone arrangements, that in turn give it inimitable physiochemical characteristics. These properties include an adjustable intrinsic energy gap, high speeds charging transport modulation efficiency, and exceptional conductance. Many scientists are interested in such novel, linear, stacked materials, including GDY. As a result, organized synthesis of GDY has been pursued, making it one of the first synthesized GDY materials. There are several methods to manipulate the band structure of GDY, including applying stresses, introducing boron/nitrogen loading, utilizing nanowires, and hydrogenations. The flexibility of GDY can be effectively demonstrated through the formation of nano walls, nanostructures, nanotube patterns, nanorods, or structured striped clusters. GDY, being a carbon material, has a wide range of applications owing to its remarkable structural and electrical characteristics. According to subsequent research, the GDY can be utilized in numerous energy generation processes, such as electrochemical water splitting (ECWS), photoelectrochemical water splitting (PEC WS), nitrogen reduction reaction (NRR), overall water splitting (OWS), oxygen reduction reaction (ORR), energy storage materials, lithium-Ion batteries (LiBs) and solar cell applications. These studies suggested that the use of GDY holds significant potential for the development and implementation of efficient, multimodal, and intelligent catalysts with realistic applications. However, the limitation of GDY and GDY-based composites for forthcoming studies are similarly acknowledged. The objective of these studies is to deliver a comprehensive knowledge of GDY and inspire further advancement and utilization of these unique carbon materials.

Dynamics of natural product Lupenone as a potential fusion inhibitor against the spike complex of novel Semliki Forest Virus.

The Semliki Forest Virus (SFV) is an RNA virus with a positive-strand that belongs to the Togaviridae family's Alphavirus genus. An epidemic was observed among French troops stationed in the Central African Republic, most likely caused by the SFV virus. The two transmembrane proteins El and E2 and the peripheral protein E3 make up the viral spike protein. The virus binds to the host cell and is internalized via endocytosis; endosome acidification causes the E1/E2 heterodimer to dissociate and the E1 subunits to trimerize. Lupenone was evaluated against the E1 spike protein of SFV in this study based on state-of-the-art cheminformatics approaches, including molecular docking, molecular dynamics simulation, and binding free energy calculation. The molecular docking study envisaged major interactions of Lupenone with binding cavity residues involved non-bonded van der Waal's and Pi-alkyl interactions. Molecular dynamic simulation of a time scale 200 ns corroborated interaction pattern with molecular docking studies between Lupenone and E1 spike protein. Nevertheless, Lupenone intearcation with the E1 spike protein conforming into a stable complex substantiated by free energy landscape (FEL), PCA analysis. Free energy decomposition of the binding cavity resdiues of E1 spike protein also ensured the efficient non-bonded van der Waal's interaction contributing most energy to interact with the Lupenone. Therefore, Lupenone interacted strongly at the active site conforming into higher structural stability throughout the dynamic evolution of the complex. Thus, this study perhaps comprehend the efficiency of Lupenone as lead molecule against SFV E1 spike protein for future therapeutic purpose.

Toward allogenizing a xenograft: Xenogeneic cardiac scaffolds recellularized with human-induced pluripotent stem cells do not activate human naïve neutrophils.

The limited availability of human donor organs suitable for transplantation has resulted in ever-increasing patient waiting lists globally. Xenotransplantation is considered a potential option, but is yet to reach clinical practice. Although remarkable progress has been made in overcoming immunological rejection, issues with functionality are still to be resolved. Bioengineering approaches have been used to create cardiac tissues with optimized functions. The use of decellularized xenogeneic cardiac tissues seeded with donor-derived cardiac cells may prove to be a viable strategy as supporting structures of the native tissue such as vasculature can be utilized. Here we used sequential perfusion to decellularize adult rat hearts. The acellular scaffolds were reseeded with human endothelial cells, human fibroblasts, human mesenchymal stem cells, and cardiac cells derived from human-induced pluripotent stem cells. The ability of the resultant recellularized rat scaffolds to activate human naïve neutrophils in vitro was investigated to measure xenogeneic recognition. Our results demonstrate that in contrast to cadaveric xenogeneic hearts, acellular and recellularized xenogeneic scaffolds did not activate human naïve neutrophils and suggest that decellularization removes the xenogeneic antigens that lead to human naïve neutrophil activation thus allowing human cells to populate the now "allogenized" xenogeneic scaffolds.

Immunogenicity of Candidate MERS-CoV DNA Vaccines Based on the Spike Protein.

MERS-coronavirus is a novel zoonotic pathogen which spread rapidly to >25 countries since 2012. Its apparent endemicity and the wide spread of its reservoir host (dromedary camels) in the Arabian Peninsula highlight the ongoing public health threat of this virus. Therefore, development of effective prophylactic vaccine needs to be urgently explored given that there are no approved prophylactics or therapeutics for humans or animals to date. Different vaccine candidates have been investigated but serious safety concerns remain over protein or full-length spike (S) protein-based vaccines. Here, we investigated the immunogenicity of naked DNA vaccines expressing different fragments of MERS-CoV S protein in mice. We found that plasmids expressing full-length (pS) or S1-subunit (pS1) could induce significant levels of S1-specific antibodies (Abs) but with distinct IgG isotype patterns. Specifically, pS1 immunization elicited a balanced Th1/Th2 response and generally higher levels of all IgG isotypes compared to pS vaccination. Interestingly, only mice immunized with pS1 demonstrated significant S1-specific cellular immune response. Importantly, both constructs induced cross-neutralizing Abs against multiple strains of human and camel origins. These results indicate that vaccines expressing S1-subunit of the MERS-CoV S protein could represent a potential vaccine candidate without the possible safety concerns associated with full-length protein-based vaccines.