CuCl2 heterogenized on metformine‐modified polystyrene resin as an antibacterial agent and recyclable nanocatalyst for Ullmann‐type C‐N coupling reactions

Merrifield Resin was functionalized with metformine and applied as a solid support to immobilize the CuCl₂. The Ps‐Met/CuCl₂ was characterized by several techniques including Fourier transform infrared (FTIR), field emission scanning electron microscopy (FESEM), energy‐dispersive X‐ray spectroscopy (EDX), wavelength‐dispersive X‐ray spectroscopy (WDX) and inductively coupled plasma (ICP). The Ps‐Met/CuCl₂ was used as an efficient recyclable solid nanocatalyst for N‐arylation of indole and aniline through coupling reactions of Ullmann‐type C‐N. The advantages of this method are easy workup, improved yields, and simple recovery via filtration. Ultimately, the Ps‐Met/CuCl₂ antibacterial property was examined against two bacteria (Staphylococcus aureus (Staph. aureus) and Escherichia coli (E. coli)) and indicated its antibacterial performance against gram negative (E. coli) bacteria and gram positive (Staph. aureus).     

Insights into the current status of privileged N-heterocycles as antileishmanial agents

Molecular Diversity - Leishmania, one of the most important neglected tropical diseases, is endemic in several regions of the world and hence regarded as a serious threat to public health. Major...     

Toxicity of copper oxide nanoparticles on Spirodela polyrrhiza: assessing physiological parameters

Research on Chemical Intermediates - The surface characteristics of nanoparticles cause their influx into the environment and lead to their interaction with fungi, algae, and plants. In the present...     

Electromagnetic fields with 217 Hz and 0.2 mT as hazardous factors for tubulin structure and assembly (in vitro study)

Nowadays exposure to extremely low frequency electromagnetic fields (ELF-EMFs) is an unavoidable fact in human societies. In spite of destructive effects of ELF-EMF such as impression on short-term memory and cognitive performances, neuroprotective and neurogeneration effects of ELF-EMF have been reported. On the other hand, microtubule (MT) proteins, the dynamic cytoskeleton proteins that are mostly located in axons, are able to produce local EMFs and possess key role in memory formation and consciousness. Therefore, MTs have strong potential to be affected by exogenous ELF-EMFs. In the present study, decline of MT polymerization was shown by transmission electron microscopy images and turbidimetry method after exposure to ELF-EMFs with 50, 100, and 217 Hz frequencies at 0.2 mT intensity. Circular dichroism and 8-anilino-1-naphthalenesulfonate (ANS) fluorometry were used to demonstrate the MT secondary and third structural changes. Decrement of MT polymerization through disruption of tubulin native structure, and increasing the β-sheets and random coils were observed in all exposure conditions. Therefore, ELF-EMFs with 50, 100, and specially 217 Hz frequencies at 0.2 mT could lead to disruption of MT functions in the neural cells.     

Morphologies of branched-chain pyrogallol[4]arenes in the solid state

A suite of branched-chain pyrogallol[4]arene (Pg) macrocycles, most of which show activity in bilayer membranes, has been prepared and studied by X-ray crystallography. The little-known branched side-chain Pgs include 2-propyl, 2-butyl, 2-pentyl, 3-pentyl, 3-heptyl, 4-heptyl, 5-nonyl and cyclohexyl. The Pgs form self-assembled structures having bilayer, capsule or, in one case, a nanotube morphology. The nanotube structure observed for C-(di-n-ethyl)pyrogallol[4]arene was confirmed by X-ray structure analysis and by transmission and scanning electron microscopies.     

Spectrofluorimetric study and determination of desipramine in the presence of β-cyclodextrin

The native fluorescence intensity of desipramine was enhanced in the presence of β-cyclodextrin in aqueous solution. The inclusion complex formation between these compounds was studied by spectrofluorimetry. A stable complex with a 2: 1 stoichiometry of β-cyclodextrin to desipramine was formed (logβ₂ = 9.29 ± 0.01). In the presence of an optimum concentration of β-cyclodextrin, the fluorescence intensity was linearly proportional to desipramine concentration in the range of 0.1–100 μg/mL (7.2 × 10^?7?1.0 × 10^?4 M) with a limit of detection of 7 × 10^?8 M. The method was successfully applied to the detection of desipramine in its tablets.     

Biocompatible APTES–PEG Modified Magnetite Nanoparticles: Effective Carriers of Antineoplastic Agents to Ovarian Cancer

Magnetite nanoparticles are particularly attractive for drug delivery applications because of their size-dependent superparamagnetism, low toxicity, and biocompatibility with cells and tissues. Surface modification of iron oxide nanoparticles with biocompatible polymers is potentially beneficial to prepare biodegradable nanocomposite-based drug delivery agents for in vivo and in vitro applications. In the present study, the bare (10 nm) and polyethylene glycol (PEG)–(3-aminopropyl)triethoxysilane (APTES) (PA) modified (17 nm) superparamagnetic iron oxide nanoparticles (SPIO NPs) were synthesized by coprecipitation method. The anticancer drugs, doxorubicin (DOX) and paclitaxel (PTX), were separately encapsulated into the synthesized polymeric nanocomposites for localized targeting of human ovarian cancer in vitro. Surface morphology analysis by scanning electron microscopy showed a slight increase in particle size (27?±?0.7 and 30?±?0.45 nm) with drug loading capacities of 70 and 61.5 % and release capabilities of 90 and 93 % for the DOX- and PTX-AP-SPIO NPs, respectively (p?<?0.001). Ten milligrams/milliliter DOX- and PTX-loaded AP-SPIO NPs caused a significant amount of cytotoxicity and downregulation of antiapoptotic proteins, as compared with same amounts of free drugs (p?<?0.001). In vivo antiproliferative effect of present formulation on immunodeficient female Balb/c mice showed ovarian tumor shrinkage from 2,920 to 143 mm³ after 40 days. The present formulation of APTES–PEG-SPIO-based nanocomposite system of targeted drug delivery proved to be effective enough in order to treat deadly solid tumor of ovarian cancer in vitro and in vivo.     

Tuning the primary resonances of a micro resonator,using piezoelectric actuation

Microbeam dynamics is important in MEMS filters and resonators. In this research, the effect of piezoelectric actuation on the resonance frequencies of a piezoelectrically actuated capacitive clamped-clamped microbeam is studied. The microbeam is sandwiched with piezoelectric layers throughout its entire length. The lower piezoelectric layer is exposed to a combination of a DC and a harmonic excitation voltage. The DC electrostatic voltage is applied to prevent the doubling of the excitation frequency. The traditional resonators are tuned using DC electrostatic actuation, which tunes the resonance frequency only in backward direction on the frequency domain. The proposed model enables tuning the resonance frequencies in both forward and backward directions. For small amplitudes of harmonic excitation and high enough quality factor, the frequency response curves obtained by the shooting method are validated with those of the multiple time scales technique. Unlike the perturbation technique, which imposes limitation on both the amplitude of the harmonic excitation and the quality factor to be applicable, the shooting method can be applied to capture the periodic attractors regardless of how big the amplitude of harmonic excitation and the quality factor are.     

Facile synthesis of magnetic MWCNT functionalised 8-hydroxyquinoline: characterisation and application for selective enrichment of cadmium ions in food samples

A simple and efficient approach for preparing modified magnetic multi-walled carbon nanotubes (MMWCNT) with 8-hydroxyquinoline was developed. This short-cut method has reduced the contact time of modification from 2 days to 10 hours. The properties of MMWCNT modified 8-hydroxyquinoline were characterised by scanning electron microscopy (SEM), vibrating sample magnetometer (VSM) and Fourier transform infrared spectrophotometer (FT-IR). This adsorbent was found to be a new, selective, low-cost and high capacitance for enrichment of cadmium in solid-phase extraction (SPE). In addition, based on the easily separated modified MMWCNT from the aqueous solutions with the help of an external magnet, no filtration or centrifugation was needed. The variables of interest in the SPE, such as pH, ionic strength, extraction time, desorption time, type and volume and concentration of eluent, were optimised. The calibration graph was linear over the range of 0.42–127 μg l^?1. The limit of detection was 0.12 μg l^?1 and the relative standard deviation of 2.25% at 30 ng ml^?1 Cd(II) ions was obtained (n = 8). The preconcentration factor and adsorption capacity of the sorbent were 160 and 60.2 mg g^?1 respectively. Finally, practical applicability of the developed adsorbent was confirmed by preconcentration of Cd(II) ions from water, vegetable and food samples.