Esterification of Cellulose with Long Fatty Acid Chain through Mechanochemical Method

Mechanochemical reaction, a green synthetic esterification route was utilized to prepare long-chain cellulose esters from microcrystalline cellulose. The influence of reaction conditions such as reaction temperature and time were elucidated. Only low dosage of oleic acid, 1-butyl-3-metylimidazolium acetate, and p-toluenesulfonyl chloride were required. The success of modification reaction was confirmed by Fourier transforms infrared spectroscopy as a new absorbance peak at 1731 cm−1 was observed, which indicated the formation of carbonyl group (C=O). Solid-state nuclear magnetic resonance was also performed to determine the structural property and degree of substitution (DS) of the cellulose oleate. Based on the results, increasing reaction temperature and reaction time promoted the esterification reaction and DS. DS values of cellulose oleates slightly decreased after 12 h reaction time. Besides, X-ray diffraction analysis showed the broadening of the diffraction peaks and thermal stability decreased after esterification. Hence, the findings suggested that grafting of oleic acid’s aliphatic chain onto the cellulose backbone lowered the crystallinity and thermal stability.

Structural, optical, and potential broad-spectrum antibacterial properties of CuO-Ag nanoparticles biosynthesized using the extract of Diospyros discolor Willd

The development of new material properties for antimicrobial agents to address the problem of antibiotic resistance is currently being explored. Silver and copper exhibit oligodynamic properties, which inhibit the growth of microorganisms. These properties are stronger at the nanoscale than the macroscale, especially for bimetallic nanoparticles (NPs). In this study, we synthesized bimetallic CuO and Ag NPs using Diospyros discolor Willd. (Velvet apple) leaf extract with three different ratios of Cu and Ag precursors: 1:0.01, 1:0.1, and 1:1 (v/v). In addition, the optical properties of these NPs were characterised using UV-Vis spectrophotometer, which showed the typical absorbance peak in the range of 300–400 nm. The size and shape of the CuO and Ag nanoparticles were analysed using a scanning electron microscope (SEM) and transmission electron microscope (TEM) images. The SEM and TEM images showed leaf-shaped CuO nanoplates and spherical AgNPs. Furthermore, the crystalline properties were analysed using x-ray diffraction (XRD). This study produced CuO-Ag nanoclusters with a particular morphology, size, and composition. The antibacterial assay showed potential broad-spectrum activity for Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis) as well as Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa).

Synthesis, Spectroscopic, and Photophysical Studies of Phosphorescent Bis(2-(2,4-difluorophenyl)pyridine)Iridium(III) Complex Containing Derivative of 1H-1,2,4-Triazole Anchillary Ligand

A cationic complex of iridium(III), [Ir(2,4-F2ppy)2(F2bpyta)]PF6 utilizing 1,2,4-triazolepyridyl as an anchillary ligand modified with a 2,6-difluorobenzyl substituent was synthesized and characterized. The aromatic signals of pyridyltriazole and phenylpyridine proton were detected in the 1H-NMR spectrum between 10.00 and 7.00 ppm. Only one singlet peak was detected at 8.46 ppm H(8) shifted to the upfield, demonstrating that C5 was coordinated to the central iridium metal. The bands exhibited in the range of 1555–1431 cm–1 in the IR spectrum because of the C=C and C=N aromatic rings stretching pyridine, phenyl, and triazole vibrations. The UV-Vis absorption spectrum showed a slight and broad absorbance peak at lower energy at a lmax = 371 nm (e = 6129 M−1 cm−1) in the visible range due to 1MLCT and 3MLCT transitions. Blue emission was observed in the steady-state emission spectral of [Ir(2,4-F2ppy)2(F2bpyta)]PF6 and the other two previously synthesized iridium(III) complexes in CH2Cl2 solutions (air-equilibrated) at room temperature. The spectrum of luminescence for the [Ir(2,4-F2ppy)2(F2bpyta)]PF6 (lem = 461 nm) is blue-shifted when compared to the [Ir(2,4-F2ppy)2(hpyta)]PF6 (lem = 469 nm), but red-shifted when related to the [Ir(2,4-F2ppy)2(mbpyta)]PF6 (lem = 454 nm).

Simple method to determine the concentration and incorporation ratio of ruthenium-labeled antibodies

Aim: Ruthenium-labeled antibodies are commonly used detection reagents in bioanalysis assays and must be characterized to ensure quality. The aim of this work was to develop a method to determine the concentration and incorporation ratio (the degree of labeling [DOL]) of ruthenium-labeled antibodies by UV/VIS spectroscopy. Materials & methods: Free SULFO-TAG compound was scanned using UV/VIS and showed an absorbance peak at 292 nm. In contrast, antibodies demonstrate UV absorbance at 280 nm. After experimentally determining the extinction coefficients at 280 and 292 nm of free ruthenium and antibody, we generated a formula based on the Beer–Lambert law that calculates both concentration and DOL of these ruthenium-labeled antibodies. Conclusion: The concentration and DOL values determined by our method were comparable to those determined from bicinchoninic acid and LC/MS for the same reagents. This method creates a faster and more accessible reagent characterization process that uses far less reagent than the more traditional alternatives.

Influence of the volume of ascorbic acid in the synthesis of copper nanoparticles mediated by chemical pathway and its stability over time

In the present investigation, the effect of ascorbic acid volume in the synthesis of copper nanoparticles (Cu NPs) mediated by chemical route and their stability over time was evaluated. For the synthesis, copper sulfate pentahydrate CuSO4 (5H2O) was used as a precursor agent and ascorbic acid (AA) as a reducing agent. Cu NPs was characterized by the following techniques: UV-Visible spectrophotometry to evaluate structural changes that are evidenced in the absorbance peak and atomic absorption spectrophotometry to define nanoparticulate concentrations material in the precipitated and supernatant phases generated. On the methodology it was possible to observe a controlled formation based on the increase in the volume of ascorbic acid in the presence of sodium hydroxide, noticing a production of Cu nanostructures with a tendency to oxidation over time. The UV-visible results showed characteristic surface plasmon resonance peaks of metallic copper for the colloid containing 1.2 mL of A.A; as well as a specific copper concentration of 0.14 ppm in the supernatant and 1519.1 ppm in the precipitate. It is also evidenced that the solution exhibits a rapid reaction on exposure to air by shifting the absorbance peak to 386 nm. In addition, it does not present notable photosensitivity with respect to exposure to sunlight.

Green synthesis of silver nanoparticles by aqueous extract of Dovyalis abyssinica fruit for antibacterial applications

Green biosynthesis technique was employed to synthesize silver nanoparticles (AgNPs). Fresh citrus fruit of Dovyalis abyssinica (vernacular name Koshim) tree was extracted by distilled water to obtain phenolic natural compounds that have reducing capacity of metallic ions to the corresponding metallic nanoparticles, in this case, silver ion to silver nanoparticles. The appearance of the UV-Vis absorbance peak at 430 nm and the color change from pale yellow reaction mixture to reddish brown colored product solution have confirmed the formation of AgNPs. FTIR data has also shown the presence of organic components from the plant with the particles that may be used as capping agents to stabilize the formed particles and to control the size. The prepared nanoparticles and the plant extract have shown antibacterial property against E. coli and S. aureus, though the effect of the AgNPs was better than the plant extract. This study contributes for the development of environmentally friendly procedures in the preparation of nanoparticles for medicine, energy or environment.

Green Synthesized ZnO Nanoparticles Mediated by Streptomyces plicatus: Characterizations, Antimicrobial and Nematicidal Activities and Cytogenetic Effects

Zinc oxide nanoparticles (ZnO-NPs) are regarded as one of the most promising kinds of materials in a variety of fields, including agriculture. Therefore, this study aimed to biosynthesize and characterize ZnO-NPs and evaluate their different biological activities. Seven isolates of actinomycetes were obtained and screened for ZnO-NPs synthesis. The isolate MK-104 was chosen and identified as the Streptomyces plicatus MK-104 strain. The biosynthesized ZnO-NPs exhibited an absorbance peak at 350 nm and were spherical in shape with an average size of 21.72 ± 4.27 nm under TEM. XRD and DLS methods confirmed these results. The biosynthesized ZnO-NPs demonstrated activity against plant pathogenic microbes such as Erwinia amylovora, Aspergillus flavus, Aspergillus niger, Fusarium oxysporum, Fusarium moniliform and Alternaria alternata, with MIC values ranging from 15.6 to 500 µg/mL. Furthermore, ZnO-NPs had a significant effect on Meloidogyne incognita, with death percentages of 88.2, 93.4 and 96.72% after 24, 48 and 72 h of exposure, respectively. Vicia faba seeds were treated with five concentrations of ZnO-NPs (12.5, 25, 50, 100 and 200 µg/mL). Low-moderate ZnO-NP concentrations (12.5–50 µg/mL) were shown to promote seed germination and seedling development, while the mitotic index (MI) decreased as the dosage of ZnO-NPs increased. Micronuclei (MNs) and the chromosomal abnormality index increased as well.

Development of rGO/Fe3O4 Composites as Glucose Biosensors

The rGO/Fe3O4 composite is one type of composites that can be used as a biosensor material, especially glucose sensors. The main ingredients of the composite synthesis are graphite and iron sand. The synthesis process of Fe3O4 was done using the coprecipitation method, while the graphite oxidation process was accomplished using the modified Hummer's method. The composites were formed using the ex-situ wet mixing method. The formed iron sand and graphite were characterized using FTIR and XRD, and it was found that Fe3O4 was formed from the appearance of the Fe-O bond, the oxidation process of graphite was seen from the appearance of the C=O bond, and the detection of Fe peaks corresponded to the cubic crystal plane. Likewise, the composites formed were also characterized using FTIR and XRD for identification of the rGO/Fe3O4 composite formation. It was proven from the presence of Fe-O and C-O bonds and the appearance of an amorphous peak of rGO in the XRD results. The performance of the rGO/Fe3O4 composites as the glucose biosensor was examined by varying the mass of Fe3O4 on the composite, using UV-Vis spectroscopy. The performance of the rGO/Fe3O4 composite biosensor in absorbing glucose reached optimum at a mass variation of 0.3 grams of Fe3O4, as demonstrated by by the lowest absorbance peak with an intensity of 0.0048 at a wavelength of 440 nm, corresponding to glucose entrappment of 7.1 mg/gram.

Characterization of Stress-Tolerant Bacteria for the Biosynthesis of Silver Nanoparticles and their Applications

The biogenesis of silver nanoparticles by microbes has become an essential branch in the field of nanotechnology because of its safe, environment-friendly, economical, and time-saving nature. In the current research work, we have screened some stress-tolerant bacteria based on pH, temperature, salt-tolerant efficacy and further utilized them for the synthesis of silver nanoparticles. The test bacterium was isolated from the soil sample through the serial dilution method on nutrient agar media (NAM). Based on identification using morphological characteristics, biochemical analysis, and 16srRNA sequencing bacteria were identified as Bacillus sp. The extracellular biosynthesis approach was used for synthesizing silver nanoparticles by Bacillus sp. Characterization of synthesized silver nanoparticles was done by using UV-Visible Spectrophotometer and absorbance peak was recorded at 430nm. Transmission electron microscopy (TEM) study of synthesized nanoparticles showed the shape of nanoparticles was spherical and hexagonal with a size ranging from 10nm-47nm. For the extracellular biosynthesis of silver nanoparticles pH was set to 7.0 and temperature at 37°C.