Highly Sensitive ‘on–off’ Pyrene Based AIEgen for Selective Sensing of Copper (II) Ions in Aqueous Media

A Fluorescent chemosensor based on pyrene scaffold, 5-diethylamino-2-(pyren-1-yliminomethyl)-phenol (PDS) is synthesized using condensation method. It displays novel aggregation-induced emission (AIE) phenomena in its aggregated/solid state. The AIE characteristic of PDS is studied in CH₃CN/H₂O mixtures at different volume percentage of water and morphology of the aggregated particles are investigated by DLS and optical fluorescence microscopic study. The probe is aggregated into ordered one-dimensional (1-D) rod like microcrystals and exhibit high efficiency of solid-state emission with green colour. By taking advantage of its interesting AIE feature, the aggregated hydrosol has been utilized as ‘off–on’ type fluorescence switching chemosensor with superb selectivity and sensitivity towards Cu²⁺ions and the limit of detection (LOD) was calculated as low as 6.3 µM. A high Stern–Volmer quenching constant was estimated to be 2.88?×?10⁵ M^?1. The proposed chemosensor with AIE feature reveals a prospective view for the on-site visual recognition of Cu²⁺ ions in fluorescent paper strips and the synthesized probe is also exploited to find out the concentration of Cu²⁺ions in real water samples.

     

Conformational Analysis of a 20‐Membered Cyclic Peptide Disulfide from Conus virgo with a WPW Segment: Evidence for an Aromatic–Proline Sandwich

A novel peptide containing a single disulfide bond, CIWPWC (Vi804), has been isolated and characterised from the venom of the marine cone snail, Conus virgo. A precursor polypeptide sequence derived from complementary DNA, corresponding to the M‐superfamily conotoxins, has been identified. The identity of the synthetic and natural peptide sequence has been established. A detailed analysis of the conformation in solution is reported for Vi804 and a synthetic analogue, CI^DWPWC (^DW3‐Vi804), in order to establish the structure of the novel WPW motif, which occurs in the context of a 20‐membered macrocyclic disulfide. Vi804 exists exclusively in the cis W3?P4 conformer in water and methanol, whereas ^DW3‐Vi804 occurs exclusively as the trans conformer. NMR spectra revealed a W3?P4 type VI β turn in Vi804 and a type II′ β turn in the analogue peptide, ^DW3‐Vi804. The extremely high‐field chemical shifts of the proline ring protons, together with specific nuclear Overhauser effects, are used to establish a conformation in which the proline ring is sandwiched between the flanking Trp residues, which emphasises a stabilising role for the aromatic–proline interactions, mediated predominantly by dispersion forces.     

Sampling and multilevel coarsening algorithms for fast matrix approximations

This paper addresses matrix approximation problems for matrices that are large, sparse, and/or representations of large graphs. To tackle these problems, we consider algorithms that are based primarily on coarsening techniques, possibly combined with random sampling. A multilevel coarsening technique is proposed, which utilizes a hypergraph associated with the data matrix and a graph coarsening strategy based on column matching. We consider a number of standard applications of this technique as well as a few new ones. Among standard applications, we first consider the problem of computing partial singular value decomposition, for which a combination of sampling and coarsening yields significantly improved singular value decomposition results relative to sampling alone. We also consider the column subset selection problem, a popular low‐rank approximation method used in data‐related applications, and show how multilevel coarsening can be adapted for this problem. Similarly, we consider the problem of graph sparsification and show how coarsening techniques can be employed to solve it. We also establish theoretical results that characterize the approximation error obtained and the quality of the dimension reduction achieved by a coarsening step, when a proper column matching strategy is employed. Numerical experiments illustrate the performances of the methods in a few applications.     

Assessment of Chemopreventive Potential of the Plant Extracts against Liver Cancer Using HepG2 Cell Line

The edible parts of the plants Camellia sinensis, Vitis vinifera and Withania somnifera were extensively used in ancient practices such as Ayurveda, owing to their potent biomedical significance. They are very rich in secondary metabolites such as polyphenols, which are very good antioxidants and exhibit anti-carcinogenic properties. This study aims to evaluate the anti-cancerous properties of these plant crude extracts on human liver cancer HepG2 cells. The leaves of Camellia sinensis, Withania somnifera and the seeds of Vitis vinifera were collected and methanolic extracts were prepared. Then, these extracts were subjected to DPPH, α- amylase assays to determine the antioxidant properties. A MTT assay was performed to investigate the viability of the extracts of HepG2 cells, and the mode of cell death was detected by Ao/EtBr staining and flow cytometry with PI Annexin- V FITC dual staining. Then, the protein expression of BAX and BCl2 was studied using fluorescent dye to determine the regulation of the BAX and BCl2 genes. We observed that all the three extracts showed the presence of bioactive compounds such as polyphenols or phytochemicals. The W. somnifera bioactive compounds were found to have the highest anti-proliferative activity on human liver cancer cells.     

Nanoconjugate Synthesis of Elaeocarpus ganitrus and the Assessment of Its Antimicrobial and Antiproliferative Properties

Cancer is one of the leading causes of death worldwide, accountable for a total of 10 million deaths in the year 2020, according to GLOBOCAN 2020. The advancements in the field of cancer research indicate the need for direction towards the development of new drug candidates that are instrumental in a tumour-specific action. The pool of natural compounds proves to be a promising avenue for the discovery of groundbreaking cancer therapeutics. Elaeocarpus ganitrus (Rudraksha) is known to possess antioxidant properties and after a thorough review of literature, it was speculated to possess significant biomedical potential. Green synthesis of nanoparticles is an environmentally friendly approach intended to eliminate toxic waste and reduce energy consumption. This approach was reported for the synthesis of silver nanoparticles from two different solvent extracts: aqueous and methanolic. These were characterized by biophysical and spectroscopic techniques, namely, UV-Visible Spectroscopy, FTIR, XRD, EDX, DLS, SEM, and GC-MS. The results showed that the nanoconjugates were spherical in geometry. Further, the assessment of antibacterial, antifungal, and antiproliferative activities was conducted which yielded results that were qualitatively positive at the nanoscale. The nanoconjugates were also evaluated for their anticancer properties using a standard MTT Assay. The interactions between the phytochemicals (ligands) and selected cancer receptors were also visualized in silico using the PyRx tool for molecular docking.     

Vibrational spectra of fluorohafnate glass

We report the first detailed measurements of fundamental vibrational spectra in fluorohafnate glass. The Raman spectrum is dominated by a single relatively broad peak in the vicinity of 570–590 cm^?1 attributed to Hf-F stretching modes, while the infrared spectrum displays two prominent broad peaks. The location of the high frequency peaks is shown to be consistent with the observed position of the infrared absorption edge.