Theoretical investigation of adsorption of the gabapentin drug on the heteroborospherene

Structural Chemistry - This is an analysis report on the use of density functional theory (DFT) to investigate the potentials of pristine and amino acid–functionalized C4B32 borospherenes in...     

Microfunnel‐filter‐based emulsification microextraction followed by gas chromatography for simple determination of organophosphorus pesticides in environmental water samples

A simple and fast method named microfunnel‐filter‐based emulsification microextraction is introduced for an efficient determination of some organophosphorus pesticides including diazinon, malathion, and chlorpyrifos in the environmental samples including the river, sea, and well water. This method is based upon the dispersion of a low‐toxicity organic solvent (dihexyl ether), as the extractant, in a high volume of an aqueous sample solution (45 mL). It is implemented without a centrifugation step, and using a syringe filter and a micro‐funnel, the phase separation and transfer of the enriched analytes to the gas chromatograph are simply achieved. By filtration of the extractant phase, a suitable sample clean‐up is obtained, and the total extraction time is just a few minutes. The factors influencing the extraction efficiency are optimized, and under the optimal conditions, the proposed method provides a good linearity (in the range of 15–1500 ng/mL (R² > 0.996). A high enrichment factor is obtained (in the range of 306–342), and the method provides low limits of detection and quantification (in the ranges of 4–8 and 15–25 ng/mL, respectively).     

Novel palladium nanoparticles supported on β‐cyclodextrin@graphene oxide as magnetically recyclable catalyst for Suzuki–Miyaura cross‐coupling reaction with two different approaches in bio‐based solvents

A novel nanocatalyst was designed and prepared. Initially, the surface of magnetic graphene oxide (M‐GO) was modified using thionyl chloride, tris(hydroxymethyl)aminomethane and acryloyl chloride as linkers which provide reactive C═C bonds for the polymerization of vinylic monomers. Separately, β‐cyclodextrin (β‐CD) was treated with acryloyl chloride to provide a modified β‐CD. Then, in the presence methylenebisacrylamide as a cross‐linker, monomers of modified β‐CD and acrylamide were polymerized on the surface of the pre‐prepared M‐GO. Finally, palladium acetate and sodium borohydride were added to this composite to afford supported palladium nanoparticles. This fabricated nanocomposite was fully characterized using various techniques. The efficiency of this easily separable and reusable heterogeneous catalyst was successfully examined in Suzuki–Miyaura cross‐coupling reactions of aryl halides and boronic acid as well as in modified Suzuki–Miyaura cross‐coupling reactions of N‐acylsuccinimides and boronic acid in green media. The results showed that the nanocatalyst was efficient in coupling reactions for direct formation of the corresponding biphenyl as well as benzophenone derivatives in green media based on bio‐based solvents. In addition, the nanocatalyst was easily separable, using an external magnet, and could be reused several times without significant loss of activity under the optimum reaction conditions.     

Electrochemical Sensing Platform Based on Graphene Oxide-chitosan for Simultaneous Determination of some Antihypertensive Drugs

The development of selective and simple methods for the determination of different analytes is of great interest. This is the first time to show the applicability of graphene oxide-chitosan (GO-CS) nanocomposite for designing an electrochemical nanosensor for determination of Amlodipine, Valsartan, and Hydrochlorothiazide, simultaneously. Differential pulse voltammetrics current of AML, HCT, and VAL increased linearly in the ranges of 0.1–110, 0.1–110, and 1–230 μM with LOD of 5.5×10⁻², 3.5×10⁻² and 8.6×10⁻² μM, respectively. Finally, GO-CS/GCE was used for the detection of these drugs in commercial tablets and compared with the reference method (HPLC).     

A Functionalized Ag2S Molecular Architecture: Facile Assembly of the Atomically Precise Ferrocene‐Decorated Nanocluster [Ag74S19(dppp)6(fc(C{O}OCH2CH2S)2)18]

A ferrocene‐based dithiol 1,1′‐[fc(C{O}OCH₂CH₂SH)₂] has been prepared and treated with a Ag^I salt to form the stable dithiolate compound [fc(C{O}OCH₂CH₂SAg)₂]_n (fc=[Fe(η⁵‐C₅H₄)₂]). This is used as a reagent for the preparation of the nanocluster [Ag₇₄S₁₉(dppp)₆(fc(C{O}OCH₂CH₂S)₂)₁₈] which was obtained in good yield (dppp=1,3‐bis(diphenylphosphino)propane).     

Gelatin-coated gold nanoparticles as an effective pH-sensitive methotrexate drug delivery system for breast cancer treatment

The present study investigates the synthesis and effectiveness of gold/gelatin nanoparticles (NPs) biopolymer as a carrier for methotrexate (MTX) drug. Two different shapes of gold particles, including spherical AuNPs (50 & 100 nm) and gold nanorods (AuNRs) with three different sizes (20, 50 and 100 nm length) were synthesized using the chemical reduction method. The effect of AuNPs size and shape on the entrapment efficiency (E.E), the release rate of the drug, and cellular uptake were investigated. The surfaces of both AuNPs and AuNRs were coated with a gelatin biopolymer, and the stability and property of the generated compounds were studied. Moreover, MTX as a chemotherapeutic agent was loaded on the gelatin-coated AuNPs/AuNRs complexes. The physicochemical properties of the gelatin-coated AuNPs/AuNRs complexes were studied using ultraviolet-visible (UV–Vis) spectroscopy, dynamic light scattering (DLS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier transform infrared (FT-IR) spectroscopy. The E.E and MTX release behavior from the complexes at pH values of 7.4 and 5.4 and temperatures of 37 and 40 °C were investigated in vitro. The cytotoxic effects of AuNPs, AuNPs-Gelatin, AuNPs-Gelatin-MTX, AuNRs, AuNRs-Gelatin, AuNRs-Gelatin-MTX and free MTX were studied. The results indicated that the E.E of AuNPs was higher than that of AuNRs. The highest release rate of the drug was related to the AuNR1-gelatin complex (pH 5.4 and temperature of 40 °C). In addition, MTX loaded AuNR2-gelatin showed the highest cytotoxic effect on the MCF-7 breast cancer cell line so that even its cell cytotoxicity was more than that of the free drug.     

A multistep collocation method for solving advection equations with delay

Advection equations with delay are appeared in the modeling of the dynamics of structured cell populations. In this article, we construct an efficient two-dimensional multistep collocation method for the numerical solution of a class of advection equations with delay. Equations with aftereffect and equations with both aftereffect and retardation of a state variable are considered. Computability of the algorithm and convergence properties of the proposed numerical method are analyzed for solutions in appropriate Sobolev spaces, and it is shown that the proposed scheme enjoys the spectral accuracy. Numerical examples are given and comparison with other existing methods in the literature is made to demonstrate the efficiency, superiority and high accuracy of the presented method.     

Solvothermal Synthesis and Characterization of PbSe Nanostructures with the Aid of Schiff-base Ligand

In this work, Pb(II)N,N-bis(salicylidene)-ethylenediamine; [Pb(salen)]; was applied as lead precursor to synthesis PbSe nanostructures. Besides [Pb(salen)], SeCl₄ and reducing agents like N₂H₄·H₂O have been employed for the production of PbSe nanostructures via a solvothermal route at 180 °C for 3 h in propylene glycol. The effect of preparation factors such as temperature, reaction time, and surfactant on the morphology of PbSe nanostructures was investigated. The experimental results indicated that PbSe synthesized at 150 and 210 °C was composed of agglomerated particles. On the other hand, the use of KBH₄ as reducing agent led to produce PbSe with higher particle size and agglomeration. The as-prepared PbSe nanostructures were characterized by XRD, SEM, TEM, EDS, and FT-IR.     

On the differences between Szeged and Wiener indices of graphs

Let G be a connected graph and η(G)=Sz(G)−W(G), where W(G) and Sz(G) are the Wiener and Szeged indices of G, respectively. A well-known result of Klav?ar, Rajapakse, and Gutman states that η(G)≥0, and by a result of Dobrynin and Gutman η(G)=0 if and only if each block of G is complete. In this paper, a path-edge matrix for the graph G is presented by which it is possible to classify the graphs in which η(G)=2. It is also proved that there is no graph G with the property that η(G)=1 or η(G)=3. Finally, it is proved that, for a given positive integer k,k≠1,3, there exists a graph G with η(G)=k.