Comparison of benzothiazole-based dyes for sensitive DNA detection

For efficient and quantitative DNA detection, fluorescence staining is the most often explored approach, which relies on non-covalent binding of dyes with double stranded DNA (dsDNA). Ethidium bromide (EB) is the most classic DNA stain, but suffers from its high carcinogenicity. A series of less toxic alternatives were developed, many of which contain the core structure of the benzothiazole ring. However, the relationship between the structure and the DNA detection performance was not illustrated. Herein, five benzothiazole dyes, namely thiazole orange, SYBR Green I, PicoGreen, SYBR Safe, and thioflavine-T, were compared for DNA detection through direct fluorescence and gel electrophoresis, with particular focus on the structure-performance relationship. It turned out that SYBR Green I is currently the best choice for DNA detection. The results in this work may be useful for future DNA-staining dye developments.     

Electrical Properties of Carboxyl Methylcellulose/Chitosan Dual-Blend Green Polymer Doped with Ammonium Bromide

This present work discusses dual-blend green polymer electrolyte (GPE)–based natural polymers, composed of carboxyl methylcellulose (CMC) and chitosan (CS), created by introducing various compositions of ammonium bromide (NH₄Br) as a dopant in the system. These GPEs were successfully prepared by the solution casting technique and characterized using electrical impedance spectroscopy (EIS). From EIS measurement, the highest room-temperature conductivity is 1.21 × 10^?5 Scm^?1 for the sample containing 20 wt.% of NH₄Br. Plot of the temperature dependence of the GPEs revealed that the system obeys the Arrhenius rule and was thermally assisted. Besides that, dielectric studies were also conducted and the data were analyzed using complex permittivity, ?^*, and complex electrical modulus, M*, to determine the sample with the highest conductivity value. Thus, this study confirmed non-Debye behavior in the sample.     

Opportunities and Challenges in the Use of TiO2 Nanoparticles Modified with Citric Acid to Synthesize Advanced Nanocomposites Based on Poly(amide-imide) Containing N,N′-(Pyromellitoyl)-bis-L-leucine Segments

In this study, the goal was the preparation, characterization, and surface morphology of poly(amide-imide)/TiO₂-citric acid nanocomposites (PAI/TiO₂-CA NCs). Owing to the high surface energy and tendency for agglomeration, the surface of TiO₂ nanoparticles was modified with citric acid. Then poly(amide-imide) was synthesized by direct polycondensation reaction of N,N′-(pyromellitoyl)-bis-L-leucine diacid with 4,4′-diaminodiphenylmethane by triphenyl phosphite and tetra-n-butylammonium bromide as a green medium. The attained polymer and modified TiO₂ nanoparticles were used to prepare PAI/TiO₂-CA NCs through ultrasonic irradiation. The resulting PAI/TiO₂-CA NC was characterized with FT-IR spectroscopy, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, and thermogravimetric analysis.     

Ultrasound-promoted,rapid, green,one-pot synthesis of 2′-aminobenzothiazolomethylnaphthols via a multi-component reaction,catalyzed by heteropolyacid in aqueous media

A one-pot, three-component condensation reaction of 2-aminobenzothiazole, 2-naphthol and appropriate aldehydes catalyzed by heteropolyacid (HPA) in an aqueous medium afforded the Mannich adduct 2′-aminobenzothiazolomethylnaphthols at 45 °C under ultrasound irradiation. This method provides several advantages such as simple work-up procedure, short reaction time and high yields.     

Efficient side-chain modification of dextran via base-catalyzed epoxide ring-opening and thiol-ene click chemistry in aqueous media

In this study, a novel approach by combining base-catalyzed epoxide ring-opening and thiol-ene click chemistry is presented for the side-chain modification of dextran. The vinyl-modified dextran is prepared by a basic epoxide ring opening reaction of allyl glycidyl ether in 0.1 mol/L NaOH, followed by thiol-addition click reaction of three model sulfhydryl compounds using water-soluble Irgacure 2959 as the photoinitiator, leading to side-chain functionalized dextran modified with carboxyl, bidentate dicarboxyl or amino groups. This is the first example of combining epoxide ring-opening and thiol- ene click chemistry for side-chain modification of dextran in aqueous media. Importantly, it may also be extended as a convenient and efficient method for the side-chain modification of other polysaccharides.     

可持续高分子-纤维素新材料研究进展

21世纪"绿色"化学已成为世界各国社会经济发展中的研究与开发战略方向.纤维素是自然界中储量最丰富的天然高分子,是重要的可再生资源以及未来的主要工业原料.然而由于纤维素存在着大量的分子内以及分子间氢键,其结构致密,难以溶解或熔融进一步加工.本文简要介绍了近几年来关于直接使用物理溶剂方法(非衍生化)对纤维素材料开发利用的新进展,主要包括以下4个方面:(1)纤维素在"绿色"溶剂-碱/尿素以及离子液体体系中的溶解和再生;(2)纳米纤维素的制备以及组装;(3)木材纳米技术的开发及利用;(4)细菌纤维素基材料等,旨在推进"绿色"技术实现纤维素资源的研究开发及利用.     

Sustainable preparation of gold nanoparticles via green chemistry approach for biogenic applications

Novel premises of ‘Green Nanotechnology’ have tremendous impacts towards industrial scale revolution. The furtive extracted from natural precursors have driven to the generation of biogenic resources for the fabrication of cutting-edge nanomaterials in simple and cost-effective process. This inspection is an intension of the coupling hypothesis of Nanotechnology via ‘Green-Chemistry’ avenue. So, as to diminish the negative effects of technological applications in the health of human beings and the environment, society is focused towards a greener future. Nanoscience assures a promising future by its improvement in green chemistry to develop the 'Greenary Nanoscience and Nanotechnology'. The improvement and execution of chemical assisted processes in order to reduce the usage of harmful substances, the ‘Green Chemistry’ approach is one and only remarkable authentication, which attributed to long range surface area and higher pore volume of gold-nanoparticles. As of now, the efficient biogenic mechanism dramatically reduces the utilization and hazardous reagents have been employed to low-price natural and waste products to yield value-added nanomaterials with extensive relevance, suggesting an economical and green solution to environmental issues. In depth investigation of this critical review illustrates, novel biogenic screening platform was also conducted against antimicrobial strains and degradation of gold-nanoparticles products well explored-from selection precursors evolved from natural extracts, as well as eventually disintegration into bio-degradable yet potentially recyclable byproducts.     

Visible light irradiation promoted catalyst-free and solvent-free synthesis of pyrano[2,3-d]pyrimidine scaffolds at room temperature

A catalyst-free and solvent-free synthetic route for convenient one-pot synthesizing pyrano[2,3-d] pyrimidine scaffolds through Knoevenagel-Michael cyclocondensation is reported using visible light irradiation as a green promoter at room temperature based on green chemistry principles. Completing the reactions takes thoroughly less time while obtaining the products in outstanding yields. This green method includes the application of non-hazardous reaction circumstances, direct work-up without column chromatographic separation, catalyst-free, solvent-free, cost effective, simple synthesis, one-pot procedure, and high atom-economy.     

Biosynthesized CuO nano-platelets: Physical properties & enhanced thermal conductivity nanofluidics

This contribution reports for the first time, room temperature biosynthesis of p-type CuO nanoparticles carried out using Callistemon viminalis’ flower extracts as a chelating agent in a process that is entirely green. Room temperature X-ray diffraction, attenuated IR total reflection spectroscopy, X-ray photoelectron and Raman spectroscopy investigations confirmed the formation of single phase Tenorite bcc monoclinic CuO nanocrystals post annealing in air, at 500 °C. Photoluminescence spectroscopy with UV emissions at 356 nm (3.47 eV) and broad visible emissions at 418 nm, 561 nm, and 664 nm, support the formation in air, at 200 °C, of CuO nanoparticles with high surface-to-volume ratios and defects. As a direct application, the biosynthesized CuO nanoplatelet-containing powder dispersed in de-ionized water showed an enhancement of the thermal conductivity from 6% to 34% and a significant stability of the PVP stabilized CuO-water nanofluid.     

Electrocatalytic activity of starch/Fe3O4/zeolite bionanocomposite for oxygen reduction reaction

The present work demonstrated an eco-friendly and facile method for the preparation of starch/Fe₃O₄/zeolite-bionanocomposite (BNC) at moderate temperature. Zeolite and starch were used as solid support and stabilizer, respectively. The analysis of UV–vis showed the appearance of surface plasmon resonance. From PXRD analysis, the incorporation of magnetite nanoparticles (NPs) in zeolite substrate results in reducing of intensities and broadening of the zeolite peaks of BNC. The TEM analysis showed the formation of highly distributed Fe₃O₄-NPs with an average diameter and standard deviation of 9.24 ± 3.57 nm. The FESEM and EDX analyses imply that Fe₃O₄-NPs were homogeneously formed on the surface of the zeolite substrate. VSM analysis illustrated the as prepared BNC possessed magnetic behaviour with a saturation magnetization and coercivity of 1.84 emu g⁻¹ and 17.76 G, respectively. The prepared BNC showed potential applicability in energy as low-cost electrode material. The BNC was used as a non-precious catalyst for oxygen reduction reaction (ORR) in the alkaline medium. The presence of starch and zeolite promoted long term stability up to 1000 cycles and avoid the dissolution and agglomeration of iron oxide. The ORR commences at the onset potential of 0 V follows by the two successive reduction peaks at −0.48 V and −1.00 V.