Nickel sulfide is regarded as a material with tremendous potential for energy storage and conversion applications. However, it exists in a variety of stable compositions and obtaining a pure phase is ...a challenge. This study demonstrates a potentially scalable, solvent free and phase selective synthesis of uncapped α-NiS, β-NiS and α-β-NiS composites using nickel alkyl (ethyl, octyl) xanthate precursors. Phase transformation and morphology were observed by powder-X-ray diffraction (p-XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The comparative efficiency of the synthesized samples was investigated for energy storage and generation applications, in which superior performance was observed for the NiS synthesized from the short chain xanthate complex. A high specific capacitance of 1,940 F/g, 2,150 F/g and 2,250 F/g was observed at 2 mV/s for bare α-NiS, β-NiS and α-β-NiS composite respectively. At high current density of 1 A/g, α-NiS showed the highest capacitance of 1,287 F/g, with 100% of Coulombic efficiency and 79% of capacitance retention. In the case of the oxygen evolution reaction (OER), β-NiS showed an overpotential of 139 mV at a current density of 10 mA/cm
, with a Tafel slope of only 32 mV/dec, showing a fast and efficient process. It was observed that the increase in carbon chain of the synthesized self-capped nickel sulfide nanoparticles decreased the overall efficiency, both for energy storage and energy generation applications.
A microwave-assisted hydrothermal method was employed to prepare thymine-modified graphitic carbon nitride quantum dots (T-gCNQDs) which are shown to be a novel fluorescent nanoprobe for Hg(II). They ...exhibit excellent optical properties (blue emission with a fluorescence quantum yield of 46%) and water solubility. The incorporation of thymine into the gCNQDs results in an enhancement in photoluminescence properties. It is found that fluorescence, best measured at excitation/emission wavelengths of 350/445 nm, is much more strongly quenched by Hg(II) compared to the thymine-free nanoprobe. The quenching is highly selective even in the presence other metal ions. This is ascribed to the formation of T-Hg(II)-T base complexes. Fluorescence drops linearly in the 1.0 to 500 nM Hg(II) concentration range, and the limit of detection is 0.15 nM. The method was applied to the determination of Hg(II) in spiked samples of tap and pond water. Recoveries were found to be >95%, thus demonstrating the practical applicability of the assay.
Graphical abstract
A microwave-assisted hydrothermal route was employed to prepare thymine-functionalized graphitic carbon nitride QDs (T-gCNQDs). A selective fluorescence quenching mechanism occurred between T-gCNQDs and Hg(II) due to thymine functionalization. T-gCNQDs was utilized to detect Hg(II) in real samples.
Pure CdS and Cu-doped CdS thin films were deposited using the spray pyrolysis technique and characterized using XRD, XPS, AFM, UV-VIS spectroscopy and two probe DC-conductivity measurements. 2%, 4% ...and 6% Cu-content was used for doping. The particle size was found to decrease from 28nm to 25.4nm upon Cu-doping. The influence of Cu-doping on the stress and dislocation per unit volume has been estimated from the XRD data. AFM images of the annealed films show changes in morphology with increase in surface roughness from 25nm to 31nm with Cu-6% doping. Reflectance and transmission measurements were studied in the spectral range of 200–1100nm to extract the optical properties variation upon copper doping. Also the band gap was found to decrease from 2.43 to 2.39eV with increase in copper content. The electrical conductivity was measured by direct record of the resistance against temperature. All films show a semiconducting behavior and incorporation of Cu on CdS increases its activation energy.
A microwave-assisted hydrothermal route was employed to prepare fluorescent tannic acid (TA)-derivatized graphitic carbon nitride quantum dots. The resulting dots display blue fluorescence (best ...measured at excitation/emission wavelengths of 350/452 nm) with a quantum yield as high as ~44%. The incorporated TA imparts a fluorescence switching behavior in that very low concentrations of Cu(II) can quench the fluorescence, while (AA) can restore it. It is presumed that AA causes Cu(II) to be transformed to Cu(I). Based on these findings, a fluorometric method was designed for AA detection. The probe allows AA to be detected with a 50 pM limit of detection and a linear analytical range that extends from 0.1 to 200 nM of AA. Real and spiked samples were successfully assayed by the probe to demonstrate its analytical applicability.
Graphical abstract
Schematic presentation of fluorescent graphitic carbon nitride quantum dots functionalized with tannic acid. Their fluorescence is quenched by Cu
2+
and recovered by ascorbic acid (AA). This is exploited in an assay with a picomolar detection limit.
Infection, trauma, and autoimmunity trigger tissue inflammation, often leading to pain and loss of function. Therefore, approaches to control inflammation based on nanotechnology principles are being ...developed in addition to available methods. The metal-based nanoparticles are particularly attractive due to the ease of synthesis, control over physicochemical properties, and facile surface modification with different types of molecules. Here, we report curcumin conjugated silver (Cur-Ag) nanoparticles synthesis, followed by their surface functionalization with isoniazid, tyrosine, and quercetin, leading to Cur-Ag.sup.INH, Cur-Ag.sup.Tyr, and Cur-Ag.sup.Qrc nanoparticles, respectively. These nanoparticles possess radical scavenging capacity, haemocompatibility, and minimal cytotoxicity to macrophages. Furthermore, the nanoparticles inhibited the secretion of pro-inflammatory cytokines such as interleukin-6, tumor necrosis factor-alpha, and interleukin-1beta from macrophages stimulated by lipopolysaccharide (LPS). The findings reveal that the careful design of surface corona of nanoparticles could be critical to increasing their efficacy in biomedical applications.
The properties of untreated sugar cane bagasse (SCB) and soft wood (SW) and their respective celluloses were investigated. The celluloses indicated improved crystallinity index values and decreased ...concentration of lignin and hemicellulose compared to their untreated counterparts. Three degradation models, Kissinger-Akahira-Sunose (KAS), Flynn-Wall-Ozawa (OFW), and Kissinger (KGR) methods were employed to determine apparent activation energy values. Generally, the thermal degradation processes of both sugarcane bagasse and soft wood included dehydration, degradation of hemicellulose and cellulose, whereas the lignin degraded from the degradation temperature of hemicellulose to the end of the cellulose. The apparent activation energy values obtained from the OFW and KAS models vary with the degree of conversion, and showed similar trends. The activation energies obtained by KGR were relatively lower than those obtained from the KAS and OFW methods.
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Alzheimer’s disease (AD) is the most common form of dementia and dementia constitutes the fifth leading cause of mortality across the globe. Available treatment modalities and drugs ...have abysmally failed to curtail AD. This study evaluated the mitigation of Aβ aggregation and anti-cholinesterase activities with the crude extracts of Ptaeroxylon obliquum and Bauhinia bowkeri. Computational studies of the most abundant phytochemicals from the crude extracts of both plants with proteins were investigated. The phytochemical composition of the different crude extracts (hexane, DCM, and ethanol) of the plants were analyzed with FTIR and GC-MS. The inhibitory potential of the extracts on BACE-1 and cholinesterase activities was determined with both computational molecular docking studies and in vitro enzyme assays. Their anti-aggregation properties were confirmed with Thioflavin-T assay and TEM.
The in silico studies revealed that though thunbergol and cyclotetradecatriene (the major constituents of the extracts) inhibited all the proteins, the latter exhibited the best inhibitory potential. The in vitro results showed that while the dichloromethane (DCM) extract of P. obliquum had the highest butyrylcholinesterase (BuChE) inhibitory activity (1.77 µg/ml), the hexane and ethanol extract of B. bowkeri exhibited the highest β-site amyloid precursor cleaving enzymes-1 (BACE-1) (30.4 µg/ml) and acetylcholinesterase (AChE) (58.11 µg/ml) inhibitory efficacy, respectively. The ethanol extract (160 μg/ml) of B. bowkeri had the most efficacious anti-aggregation activity.
This study suggests that the plants could possess neuroprotective effects and could also be sources of anti-AD novel drugs.
How to cite: Ojo MC, Mosa RA, Osunsanmi FO, et al. In silico and in vitro assessment of the anti-β-amyloid aggregation and anti-cholinesterase activities of Ptaeroxylon obliquum and Bauhinia bowkeri extracts. Electron J Biotechnol 2024;68. https://doi.org/10.1016/j.ejbt.2023.11.004.
Eco-friendly and cost-effective catalysts with multiple active sites, large surface area, high stability and catalytic activity are highly desired for efficient water splitting as a sustainable green ...energy source. Within this line, a facile synthetic approach based on solventless thermolysis was employed for the simple and tunable synthesis of Ni
Mg
Fe
O
(0 ≤ x ≤ 1) nanosheets. The characterization of nanosheets (via p-XRD, EDX, SEM, TEM, HRTEM, and SAED) revealed that the pristine ferrites (NiFe
O
and MgFe
O
), and their solid solutions maintain the same cubic symmetry throughout the composition regulation. Elucidation of the electrochemical performance of the nanoferrite solid solutions showed that by tuning the local chemical environment of Ni in NiFe
O
via Mg substitution, the intrinsic catalytic activity was enhanced. Evidently, the optimized Ni
Mg
Fe
O
catalyst showed drastically enhanced HER activity with a much lower overpotential of 121 mV compared to the pristine NiFe
O
catalyst. Moreover, Ni
Mg
Fe
O
catalyst exhibited the best OER performance with a low overpotential of 284 mV at 10 mA/cm
in 1 M KOH. This enhanced electrocatalytic activity could be due to improved electronic conductivity caused by the partial substitution of Ni
by Mg
in the NiFe
O
matrix as well as the synergistic effect in the Mg-substituted NiFe
O
. Our results suggest a feasible route for developing earth-abundant metal oxide-based electrocatalysts for future water electrolysis applications.
Phase pure SnS nanosheets were synthesized by a hot injection method from a new single molecular precursor (SMP), dibutyl-bis(piperidinedithiocarbamato)tin( iv ) in oleylamine at 230 °C. The tin ...complex was characterized by single crystal X-ray crystallography, nuclear magnetic resonance, thermogravimetry and microelemental analysis. The complex is thermally stable up to 260 °C, after which it decomposes in a single step with a major mass loss between 260 °C and 300 °C. The thermolysis of the as-prepared precursor was carried out in oleylamine between 190 and 230 °C. The formation and shape evolution of SnS was investigated using high resolution electron microscopy. The mechanism of the time dependent growth of SnS from spherical particles into nanosheets is proposed.
A number of previously reported studies suggest that synthetic gold nanoparticles (AuNPs) are capable of stabilising proteins against heat stress in vitro. However, it remains to be understood if ...AuNPs confer stability to proteins against cellular stress in vivo. Heat shock proteins (Hsps) are conserved molecules whose main role is to facilitate folding of other proteins (chaperone function). Hsp70 (called DnaK in prokaryotes) is one of the most prominent molecular chaperones. Since gold nanoparticles exhibit chaperone-like function in vitro, we investigated the effect of citrate-coated gold nanoparticles on the growth of E. coli BB1553 cells that possess a deleted dnaK gene. We further investigated the effects of the AuNPs on the solubility of the E. coli BB1553 proteome. E. coli BB1553 cells exposed to AuNPs exhibited cellular defects such as filamentation and plasma membranes pulled off the cell wall. The toxic effects of the AuNPs were alleviated by transforming the E. coli BB1553 cells with a construct expressing DnaK. We also noted that cells in which DnaK was restored exhibited distinct zones to which the nanoparticles were restricted. Our study suggests a role for DnaK in alleviating nanoparticle induced stress in E. coli.
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