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  • Open access
  • 38 Reads
Facile fabrication of DNA biosensors based on oxidized carbon black and graphite oxide

We investigated electrochemical sensors based on graphite oxide (GrO) and oxidized carbon black (CbO). GrO and CbO were synthesized by the modified Hummers method. We determined the degree of functionalization using Fourier transform infrared spectrometry (FT-IR). Single-stranded DNA (ssDNA) probes were synthesized with a 5’ primary amine for attachment. These ssDNA oligonucleotides were immobilized on GrO and CbO using standard 1-Ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC) coupling. This formed an amide bond between DNA-amine and carboxyl groups on GrO and CbO. GrO and CbO were used instead of graphite in a carbon paste material. This significantly enhanced the sensitivity of the biosensor for the reverse-complementary DNA.
We detected reverse-complimentary DNA using Electrochemical Impedance Spectroscopy (EIS) and Cyclic Voltammetry (CV) in a ferricyanide solution. The solution was spiked with the ssDNA oligonucleotide with the reverse-complementary sequence of the immobilized probe. The change in current or impedance was measured. We present early work on optimizing the fabrication method for DNA-functionalized carbon electrodes. Working electrodes were fabricated by drop-casting the active material onto a glassy carbon electrode surface.

  • Open access
  • 69 Reads
Intermolecular quenching of Edans/Dabcyl donor-acceptor FRET pair

Fluorescence resonance energy transfer (FRET) is one of the most sensitive techniques for monitoring biochemical events. The donor-acceptor pair 5-(2´-aminoethyl)aminonaphthalene sulfonic acid (Edans) and 4-[[4´-(N,N-dimethylamino)phenyl]diazenyl]benzoic acid (Dabcyl) has excellent spectral overlap between the fluorescence emission of the former and the absorption of the latter, resulting in efficient energy transfer. Strategies incorporating this donor-acceptor pair have been successfully applied to fluorescence-based assays of HIV-1 protease, human neutrophil elastase, human cytomegalovirus protease, and hepatitis C virus protease. The use of a FRET strategy is of particular importance considering our current interest in the design of a formulation able to respond to internal and external stimuli to locally release a cocktail of immunostimulating and chemotherapeutic drugs against colorectal cancer, using a fluorescence reporting system to monitor in real time the response to the treatment.

In this communication, considering a fluorescent probe of peptidic nature, the mechanism of quenching of the FRET pair Edans/Dabcyl was studied by performing photometric and fluorimetric measurements at pH = 7.5 in phosphate buffer. The quenching mechanism was studied using the Stern–Volmer plot, confirming that this FRET pair was involved in a dynamic quenching process.

  • Open access
  • 76 Reads
Removal of lead ion from aqueous solution by Metal organic Framework

Since Pb(II) is one of the toxic water contamination agents, finding an efficient way to remove it from wastewater has become a serious issue in the world. Herein, a metal-organic framework, formulated as [Zn2(oba)2(bpfb)]·(DMF)5 , with amide-decorated pores was prepared to investigate its potential in Pb(II) removal performance. At first, various determining factors including pH and adsorbent dosage were optimized. Then, the MOF adsorption capacity was measured about 434.7 mg. g-1. Moreover, reusability feature and effect of competitive cations were checked. Adsorption-desorption tests showed that during three cycles, the MOF could act with favorable efficiency. Modeling calculations illustrate that pseudo-second-order and Langmuir models provide the best description for adsorption mode. Based on these models, monolayer adsorption behavior was responsible for adsorption process through chemical interaction between the analyte and the walls of MOF. Also, the possible adsorption mechanism was examined by exploiting of FTIR spectroscopy, EDS and SEM images.

  • Open access
  • 67 Reads
Halloysite nanotubes modified by chitosan as an efficient and eco-friendly heterogeneous nanocatalyst for the synthesis of heterocyclic compounds

Halloysite nanotubes (HNTs) are the subset of clay minerals with the same ratio of tetrahedral silicon and octahedral aluminum sheets. The special features of HNTs like tubular morphology, biocompatible, availability and porosity lead to use it in the various application such as drug delivery, catalyst, self-lubrication, and wastewater treatment. Also, HNTs could be modified with different polycation and polyanion due to the different charge of the outer and inner surface of nanotubes. Chitosan as a polycation which obtained by alkaline N-deacetylation of chitin. In recent years, much attention has been paid to this compound due to its unique features such as non-toxic, hydrophilic, biocompatible, biodegradable and antibacterial activity. Because of the biomedical activity of chitosan, it can be used for drug delivery systems, wound healing and tissue engineering. In the structure of chitosan, there are a large number of amine and hydroxyl groups. Therefore, it can be modified by fictionalization with organic and inorganic material. In this study, HNTs modified by chitosan and its catalyst activity was investigated in the synthesis of pyranopyrazole derivatives. The use of efficient, green and reusable nanocatalyst are some advantages of the present work.

  • Open access
  • 57 Reads
Valorization of plant extracts by encapsulation in lipid nanosystems for application as potential insecticides

Plants have been used for centuries to treat diseases and are considered as an important source of new antimicrobial agents. Plant extracts can be isolated and their composition determined, being widely employed in the pharmaceutical and cosmetic industries. A less explored and potential application is the use as green insecticides/insect repellents, as an alternative to current pesticides.

Despite the desirable properties, many of the isolated components (phytochemicals) present limitations on their use, due to high volatility and easy degradation when exposed to air. Nanoencapsulation techniques arise as promising strategies to allow the preservation and controlled release of plant extracts.

In this work, a series of plant materials, Tamus communis L., Tagetes patula L. and Rute graveolens L., were subjected to Soxhlet extraction using various solvents and times of extraction. The vegetable material used was dried according to standard procedures. The extracts obtained were characterized and submitted to biological studies, to assess their potential against the insect cell line Sf9. Encapsulation assays in lipid nanosystems were carried out, with encapsulation efficiencies ranging from 63% to 93%.

  • Open access
  • 39 Reads
Methyl Orange Adsorption by Fe2O3@Co-Al Layered Double Hydroxide

A magnetic composite consisting of iron oxide and a cobalt-aluminum layered double hydroxide, Fe2O3@Co-Al LDH was prepared through linking of Fe2O3 to Co-Al LDH by sodium acetate. Layered double hydroxides are generally described as [M2+1–xM3+x(OH)2][An–x/n·mH2O], where M2+ and M3+ are divalent and trivalent metal cations, respectively, and A is an n-valent interlayer guest anion. The composite was characterized by XRD, FTIR and UV-Vis. spectroscopy methods. Afterwards, the composite was used for methyl-orange adsorption in aqueous solution. The UV-Vis spectrum indicates that the adsorption process was satisfying. In effect, after several washings of the composite, no decrease of the adsorption capacity was observed.

  • Open access
  • 48 Reads
Thermophysical characterization of TFSI based ionic liquid and lithium salt mixtures

The ionic liquids (ILs) doped with metal salts have become a real alternative as electrolytes for batteries, but the right chose of these compounds for reaching the adequate properties and performance is still a challenge and strategies are therefore needed for achieving it.

Thermophysical properties of the IL 1-butyl-1-methylpyrrolidinium bis[(trifluoromethyl)sulfonyl]imide ([bmpyr][TFSI]) and its mixtures with the Bis(trifluoromethane)sulfonimide lithium salt (from 0.1 m to saturation level) were determined in this work. These properties are density (ρ), speed of sound (U), and corresponding derived magnitudes, such as the bulk modulus and the thermal coefficient, as well as electric conductivity (s) against temperature.

Density shows a linear decreasing dependence with temperature and a clear increase with the salt addition, whereas thermal expansion coefficient increases with temperature and salt addition.

Speed of sound decreases with both temperature and salt concentration, and the adiabatic compressibility calculated by means of the well-known Laplace equation increases, as expected, with temperature in all the studied cases although a small variation with concentration can be observed. The thermal coefficient increases with temperature and with salt concentration.

Electric conductivity increases with temperature following the Vogel-Fulcher-Tammann (VFT) equation and decreases with the addition of salt.

  • Open access
  • 40 Reads
Adsorption of Rhodamine-B from aqueous solution by activated carbon from almond shell

The activated carbon is prepared from an almond shell, which is chemically activated by H2SO4. In the present study, the adsorption of Rhodamine-B from water by activated carbon has been investigated and compared. The effect of pH value, initial concentration of dissolved and amount of adsorbent on the adsorption of Rhodamine-B by the mentioned adsorbents were investigated. Results showed that the adsorption process was highly dependent on pH. Maximum Rhodamine-B removal was achieved when the final pH is 11. Maximum Rhodamine-B removal efficiencies were obtained by an almond shell (70%). Adsorption test results revealed that Rhodamine-B adsorption on the studied adsorbents could be better described by Langmuir isotherm.

  • Open access
  • 62 Reads
Applying benzenetetracaboxylic acid as a linker in the synthesis of a porous Ba(II)-based MOF by ultrasonic method

Metal−organic frameworks (MOFs) which are inorganic-organic hybrid porous materials, prepared from metal ions/clusters and multidentate organic ligands have evolved to be the next generation utility materials because of their usability in diverse applications. [1] MOFs as a class of interesting materials have attracted great attention due to their controllable pore size and elaborately designed pore structure. In the past two decades, MOFs have exhibited versatile potential applications such as gas storage, gas separation, heterocatalysis, sensors, and luminescence. [2] Most of the research so far are focused on MOFs based on transition metal ions or rare-earth ions. However, the main group alkaline earth metals are receiving increasing attention, recently. [3] In this review, A porous Ba(II)-based MOF was synthesized by Ultrasonic method using benzene-1,2,4,5-tetracaboxylic acid, as an organic linker; which was characterized by X-Ray Diffraction, Fourier Transform Infrared spectroscopy and Scanning Electron Microscopy.

  • Open access
  • 42 Reads
Antibacterial and Molecular Study of Thiourea Derivative Ligand and its Dimethyltin(IV) Complex with the Superior of its Copper(II) Complex as a Hepatocellular Antitumor Drug

1-benzoyl(1,2,4-triazol-3-yl)thiourea [BTThU] ligand and its [dimethyltin(IV), Pd(II) and Cu(II)] complexes are synthesized. The complexes are formed in molar ratio Cu(BTThU)2, DMT(BTThU)2 and Pd(BTThU)2. The characterization has been done by using different physicochemical methods as elemental analyses, IR, 1H NMR DMSO-d6 and molar conductance measurements. The stability constants of the formed species that produced from the interaction of [BTThU] with dimethyltin(IV) [DMT], dibutyltin(IV) [DBT] and diphenyltin(IV) [DPT] were determined potentiometrically using the non-linear least-square program MINIQUAD-75 in 50% ethanol–water mixture and 0.1M ionic strength at 25oC. Concentration distribution diagrams for these system were evaluated. The theoretical conformational structure analyses were performed using density functional theory for thiol and thione tautomeric forms of [BTThU] ligand and its complex at B3LYP functional with 6-311G basis set for ligand and LANL2DZ basis set for complex. The theoretical vibrational frequency values of the optimized structures were calculated. The charge distribution within the ligand and its dimethyltin(IV) complex was calculated using Mulliken population analysis of [MPA] and natural population analysis [NPA]. The biological activity of BTThU ligand and its dimethyltin(IV) complex were tested in vitro against some selected species of fungi and bacteria. The hepatocellular antitumor effect of all compounds was investigated.