A signal amplification by QDs used for ferrocene-labeled sandwich aptasensor for determination of Hg2+ in water samples

In this paper, the design of a novel sandwich-type electrochemical aptasensor was reported for an ultrasensitive mercury ion (Hg²⁺) detection in water samples, which labeled with two-labeled aptamer (Apt) sequences. The used Apts were Apt1 and Apt2 as the capture and signal probe, respectively. The Apt1 probe was immobilized on the poly(4-aminobenzoic acid) (p-ABA) and quantum dots (QDs) film as the platform, as well as the Apt2 reporter was labeled with ferrocene. In the presence of Hg²⁺, the strong coordination complex has been formed between the specific thymine of the Apt1, Hg²⁺, as well as the thymine of the Apt as T–Hg²⁺–T adduct. The QDs and p-ABA were applied for increasing the conductivity of platform and suitable binding of the recognition elements. Under the optimized conditions, the constructed aptasensor illustrated either a wide linear relationship between the logarithm of Hg²⁺ concentration and current, from 0.05 to 100 nM and also an excellent low limit of detection of 0.01 nM. The quality of carefully choosing, an excellent stability and specificity sensitivity of the designed aptasensor, was investigated by spiked tap water samples as real sample. Moreover, the aptasensor exhibits the good reproducibility as well as has high selectivity for the other cations. The recoveries of the Hg²⁺ assay of the tap water samples were acquired satisfactorily which imply the generated aptasensor can use Hg²⁺ measurement in the real laboratories.

     

DFT Investigation of the Potential of B<Subscript>21</Subscript>N<Subscript>21</Subscript> and Al<Subscript>21</Subscript>P<Subscript>21</Subscript> Nanocages as Anode Electrodes in Metal Ion Batteries

In present paper, the potential of B₂₁N₂₁ and Al₂₁P₂₁ nanocages as anode electrodes of Li-ion, Na-ion and K-ion batteries by using of density functional theory was investigated. The effects of adoption of B₂₁N₂₁ and Al₂₁P₂₁ nanocages with halogen atoms on potential of metal-ion batteries were examined. Results showed that Al₂₁P₂₁ as anode electrode in metal ion batteries has higher potential than B₂₁N₂₁. Results indicated that K-ion battery has higher cell voltage than Li-ion and Na-ion batteries. Results showed that adoption of B₂₁N₂₁ and Al₂₁P₂₁ with halogen atoms increased the cell voltage of metal-ion batteries. Results showed that F-doped metal-ion batteries have higher cell voltage than Cl- and Br-doped metal-ion batteries. It can be concluded that F–Al₂₀P₂₁ as anode electrode in metal-ion battery has higher potential than F–B₂₀N₂₁.     

Heteropolyacid immobilized on polymer/magnetic zeolite nanocomposite as a new and recyclable catalyst for the selective oxidation of alcohols

A new magnetic oxidation catalyst was prepared using immobilization of tungstophosphoric acid on poly(N-vinylimidazole) entrapped magnetic nanozeolite and characterized by FTIR, TGA, XRD, SEM, TEM, EDX, VSM, and ICP-OES. The resulting heterogeneous catalyst displays high catalytic performance for selective oxidation of alcohols compared to the other catalysts. The catalyst could be reused eight times without any loss of catalytic activity.     

Reaction Between Alkyl Isocyanides and Cyclic 1,3-Diketones: A Convenient Synthesis of Functionalized 4<Emphasis Type="Italic">H</Emphasis>-Pyrans

Summary. Alkyl isocyanides react with dialkyl acetylendicarboxylates in the presence of CH-acids such as cyclopentane-1,3-dione, cyclohexane-1,3-dione, or 5,5-dimethylcyclohexane-1,3-dione to afford highly functionalized 4H-pyrans in fairly high yields. In the case of reaction between dimethyl acetylenedicarboxylate and 5,5-dimethylcyclohexane-1,3-dione in the presence of cyclohexyl isocyanide or benzyl isocyanide tetrahydro-cyclopenta[b]pyran derivatives were isolated in addition to the 4H-pyran system. The free energy barrier (96.9kJmol^–1) for restricted rotation around the polarized double bond of the enaminone moiety in dimethyl 2-[cyclohexylamino-(4,4-dimethyl-2,6-dioxocyclohexylidene)methyl]but-2-enedioate was determined by dynamic NMR spectroscopy.     

Magnetic metal-organic frameworks for the extraction of trace amounts of heavy metal ions prior to their determination by ICP-AES

Microchimica Acta - The authors describe the preparation of two kinds of metal-organic frameworks (MOFs), referred to as TMU-8 and TMU-9. The MOFs were applied to the preconcentration of the ions...     

Simple design of an aligned transparent biofilm by magnetic particles and its cellular study

The aim of this study was to produce aligned biodegradable films. In this study, we used magnetic microparticles and strong magnetic field for orientation of gelatin gels. The samples were evaluated by microscopic analyses and cell culture assays with Schwann cells. Results of structural analyses showed a good arrangement and orientation of films under strong magnetic field with movement of magnetite particles. Cellular experiments showed a good cell adhesion and orientation on the designed films compared with those on unmodified ones. This aligned guide appears to have the right organization for testing in vivo nerve tissue engineering studies. Copyright © 2016 John Wiley & Sons, Ltd.     

Propylsulfonic acid functionalized nanozeolite clinoptilolite as heterogeneous catalyst for the synthesis of quinoxaline derivatives

In this work, the natural nanozeolite clinoptilolite (Nano CP) was successfully functionalized by propylsulfonic acid and applied as efficient heterogeneous catalyst for the synthesis of quinoxaline derivatives in aqueous media. The nanocatalyst was characterized by various techniques such as CHN, XRD, FT-IR, BET, TGA/DTA, SEM, TEM and TEM-EDS. The results show its applicability as green, reusable and promising catalyst in organic synthesis. It was found that the nanocatalysts could be recycled and reused eight times without significant loss of catalytic activities.     

Extraction and preconcentration of formaldehyde in water by polypyrrole‐coated magnetic nanoparticles and determination by high‐performance liquid chromatography

In this study, a simple and rapid extraction method based on the application of polypyrrole‐coated Fe₃O₄ nanoparticles as a magnetic solid‐phase extraction sorbent was successfully developed for the extraction and preconcentration of trace amounts of formaldehyde after derivatization with 2,4‐dinitrophenylhydrazine. The analyses were performed by high‐performance liquid chromatography followed by UV detection. Several variables affecting the extraction efficiency of the formaldehyde, i.e., sample pH, amount of sorbent, salt concentration, extraction time and desorption conditions were investigated and optimized. The best working conditions were as follows: sample pH, 5; amount of sorbent, 40 mg; NaCl concentration, 20% w/v; sample volume, 20 mL; extraction time, 12 min; and 100 μL of methanol for desorption of the formaldehyde within 3 min. Under the optimal conditions, the performance of the proposed method was studied in terms of linear dynamic range (10–500 μg/L), correlation coefficient (R² ≥ 0.998), precision (RSD% ≤ 5.5) and limit of detection (4 μg/L). Finally, the developed method was successfully applied for extraction and determination of formaldehyde in tap, rain and tomato water samples, and satisfactory results were obtained.     

Synthesis of 2H-thiochromene derivatives (microreview)

Chemistry of Heterocyclic Compounds - The microreview considers recent methodologies for the synthesis of 2H-thiochromenes including enantioselective synthesis, multistep synthesis,...     

A combined multicomponent-acid catalyzed cyclization reaction as an efficient route to novel tricyclic pyrrolo[2,1-a]isoquinoline derivatives

A simple, new two-step procedure for the synthesis of novel tricyclic pyrrolo[2,1-a]isoquinoline derivatives is described. The initially prepared polysubstituted pyrroles obtained via the four-component condensation of arylglyoxals, cyclic 1,3-dicarbonyls, aminoacetaldehyde dimethyl acetal, and β-keto esters subsequently underwent intramolecular acid-catalyzed cyclization to the desired products in moderate to good yields.