Solvent composition regulates the Se: Sb ratio in antimony selenide nanowires deposited from thiol–amine solvent mixtures

Antimony selenide (Sb2Se3), a V2VI3 semiconductor with an intriguing crystal structure, has demonstrated improved power conversion and solar-to-hydrogen efficiencies in recent years. Depositing antimony selenide nanowires (NWs) from a solution...

Temperature Dependent Emission Properties of ReI Tricarbonyl Complexes with Dipyrido-Quinoxaline and Phenazine Ligands

In this work, the emission properties of fac-[Re(CO)3(NN)(py)]+, NN = 1,10-phenanthroline (phen), dipyrido[3,2-f:2’,3’-h]quinoxaline (dpq) and dipyrido[3,2-a:2’3’-c]phenazine (dppz); py = pyridine were investigated in different temperatures, ranging from 80 to 300 K, and in different solvent mixtures and in polymethyl methacrylate. The changes observed in the emission quantum yields were rationalized based on a two-level excited state model, in which the nonemissive upper state is thermally populated and decays faster than the lowest lying emissive state. fac‑[Re(CO)3(dpq)(py)]+ is a metal-to-ligand charge transfer (MLCT) emitter as the complex with phen but exhibits smaller emission quantum yields, being more sensitive to the solvent. This behavior was rationalized by quantum-mechanical calculations including the spin-orbit coupling matrix elements, revealing that intersystem crossing from the lowest singlet excited state in fac- [Re(CO)3(dpq)(py)]+ likely occurs to triplet states lying at higher energies. Similar behavior were observed for fac-[Re(CO)3(dppz)(py)]+, although the later exhibits intraligand emission that are strongly quenched in fluid solutions by low-lying MLCT states. The fundamental studies carried out here provide new insights on the excited state dynamics of ReI complexes with dipyridoquinoxaline and phenazine ligands and can contribute for further advances on their application as luminescent probes.

Effects of Different Extracting Solvents on Non-Phenolic Phytochemical Profiles of Selected Nigerian Spices and Spice-treated Foods

The aim of this research was to investigate the impact of extraction solvents on the non-phenolic phytochemical profiles of selected spices (Ocimum viride, Monodora myristica, Monodora tenuifolia and Tetrapleura tetraptera) and spice-treated foods in southern part of Nigeria. The spice samples were processed into powder for antioxidant screening. The spice extracts were obtained from the samples using 5 extracting solvents [distilled water, 95 % methanol, acetone / hexane (1:1 v/v), n-hexane / methanol / acetone (2:1:1, v/v/v) and acetone / water / acetic acid (70:29.5:0.5, v/v/v)]. Water extracts were obtained from beef, pork and fluted pumpkin leaves. The alkaloid, saponin, oxalate and phytate components of the spice extracts and the spice-treated foods were evaluated using standard methods. The laboratory analyses were performed at analytical laboratory, National Centre for Energy Research and Development, University of Nigeria, Nsukka during the 3rd quarter of 2020. The percentage yield of the extracts were low (0.32 - 0.96 %) and varied widely among extracting solvents, spices and spice-treated foods. M. myristica and T. tetrpleura had the highest yield, 0.96, in methanol extracts. Phytochemical contents differed significantly (p < 0.05) among spices, extracts of the same spice and among spice-treated foods. Spices had high contents of oxalate (2.0 – 7.0 mg/100 g), alkaloid (0.8 – 5.76 mg/100 g) and phytate (2.14 – 3.88 mg/100 g) but relatively low content of saponin (0.03 – 0.736 mg/100g). Methanol alone or in combination with other solvents extracted higher amounts of phytochemicals (0.96 %) than other solvent mixtures from the spices. Phytochemical contents of spice-treated foods were in the order: vegetable > rice > pork > beef.

Purification of Chitin from Pupal Exuviae of the Black Soldier Fly

Purpose Chitin purification from remains (pupal exuviae after metamorphosis to adult flies) of Hermetia illucens farming was optimized performing demineralization, deproteinization and bleaching under different conditions. The optimal parameters to obtain high-purity chitin were determined. Methods Dried and ground pupal exuviae, whose composition was initially determined, were demineralized using six different acids. Proteins were removed with a NaOH treatment in which temperature, molarity and duration were varied in a randomized experiment. Bleaching was carried out testing ten different chemicals, including NaOCl, H2O2, solvent mixtures and enzymes. The efficiency of each step was determined to assess the optimal conditions for each of them. The resulting chitin was subjected to spectroscopic characterization. Results The highest demineralization efficiency (90%) was achieved using 0.5 M formic acid for 2 h at 40 °C, confirming the validity of organic acids as a more sustainable alternative to inorganic acids. The treatment with 1.25 M NaOH at 90 °C for 4 h showed the highest deproteinization efficiency, removing 96% of the proteins. Temperature and NaOH concentration were the significant parameters for deproteinization efficiency. The most efficient bleaching treatment was with 6% NaOCl at 60 °C for 1 h (67% efficiency). H2O2 could also be a valid alternative to avoid environmental risk related to chlorine-containing compounds. At the end of the purification process 17% of the original biomass was retained with a chitin content of 85%, corresponding to a chitin yield of 14% related to the initial biomass. Solid-state nuclear magnetic resonance showed that the purified chitin had a degree of acetylation of 96% and X-ray powder diffraction gave a crystallinity index of 74%. Conclusion This investigation shows an optimized method for extraction of high-purity chitin from H. illucens pupal exuviae, supporting the validity of insect-farming remains as source of this versatile biopolymer. Graphical Abstract

Glibenclamide-Loaded Polyvinylpyrrolidone (PVP) Nanoparticles and Glibenclamide-Loaded Soluplus® Nanomicelles Intended for Parenteral Administration: Effect of Solvents Mixtures on the Electrosprayed Nanoparticles and In vitro Characterization

Background and Objective: Glibenclamide (GB) is showing promising results in central nervous system (CNS) injuries treatment where intravenous administration of GB could overcome the oral limitations and assure maximum bioavailability. Dry powder of GB nanoparticles reconstituted for parenteral administration was prepared through electrospraying. Methods: The drug was incorporated with two polymers, polyvinylpyrrolidone (PVP) and Soluplus® (SP), at ratios 1:4 and 1:2 (GB/polymer). Different solvent mixtures were used to formulate the particles. Physicochemical characteristics were investigated. Results: The size of the GB-PVP nanoparticle ranged between (409-775) nm with a spherical, disk, fractured and, agglomerated morphology, while those of the GB-SP nanomicelles were of (447-785) nm with mostly irregular morphology, in consequence to the used solvents mixtures. The high encapsulation efficiency ≥ 98% reflects the well dispersed drug molecules within the polymer matrix, further confirmed by X-ray diffraction and infrared spectroscopy. GB-SP colloidal dispersions showed neutral zeta potentials with a cloud point of 36 ˚C, indicating prolonged circulation time and stability after parenteral administration. GB/SP nanomicelles at ratio 1:4 showed a sustained drug release reaching ≥ 94% in 36 hours. Conclusion: The GB-SP nanomicelles with extended drug release and regarding physicochemical properties represent a remarkable drug delivery system for parenteral administration.