Fe3O4@SiO2 nanoparticles–functionalized Cu(II) Schiff base complex with an imidazolium moiety as an efficient and eco-friendly bifunctional magnetically recoverable catalyst for the Strecker synthesis in aqueous media at room temperature

Cu(II) Schiff base complex supported on Fe₃O₄@SiO₂ nanoparticles was employed as a magnetic nanocatalyst (nanocomposite) with a phase transfer functionality for the one-pot preparation of α-aminonitriles (Strecker reaction). The desired α-aminonitriles were obtained from the reaction of aromatic or aliphatic aldehydes, aniline or benzyl amine, NaCN, and 1.6 mol% of the catalyst in water at room temperature and good to excellent yields were obtained for all substrates. The catalyst was characterized analytically and instrumentally including Fourier-transform infrared spectroscopy, X-ray diffraction, thermogravimetric, nuclear magnetic resonance, energy-dispersive X-ray spectroscopy, inductively coupled plasma spectroscopy, vibrating-sample magnetometry analysis, dynamic light scattering, Brunauer–Emmett–Teller surface area, field emission scanning electron microscopy, and transmission electron microscopy analyses. The reaction mechanism was investigated, in which the performance of the catalyst as a phase transition factor seems to be probable. The catalyst showed high activity, high turnover frequency (TOF)s, significant selectivity, and fast performance toward the Strecker synthesis. The nanocatalyst can be readily and quickly separated from the reaction mixture with an external magnet and can be reused for at least seven successive reaction cycles without significant reduction in efficiency.     

Evaluation of new 99mTc-labeled HYNIC-bombesin analogue for prostate cancer imaging

Journal of Radioanalytical and Nuclear Chemistry - In this study, we introduce a new 99mTc-radiolabeled bombesin derivative for imaging of prostate cancer (PC). We used 6-hydrazinonicotinamide...     

A green approach for the electroorganic synthesis of 2-[(4-methyl-2-pyridyl)amino]-1,4-benzenediol derivatives in aqueous solution

The electrochemical synthesis of some new 2-[(4-methyl-2-pyridyl)amino)-1,4-benzenediol derivatives was performed via the electrochemical oxidation of hydroquinones in the presence of 2-amino-4-methylpyridine in an aqueous solution. The results demonstrate that electrogenerated p-benzoquinone participated in the Michael-type addition reaction via an electrochemical–chemical (EC) reaction mechanism pathway and converted to the corresponding 2-[(4-methyl-2-pyridyl)amino)-1,4-benzenediol derivatives. These new compounds have been synthesized in high yields and purity without using any toxic reagents or catalyst at the surface of carbon electrode.     

DFT Study of PH3 Physisorption and Chemisorptions on Boron Nitride Nanotubes

The adsorption of PH₃ molecules on the NiB,N-doped(4,4) and (5,5) BNNT_S surfaces has been investigated using density functional theory (DFT). The adsorption energies, geometric and electronic structures of the adsorbed systems were studied to judge the possible application of NiB,N-doped BNNT_S in PH₃ monitoring systems. Our calculated results showed that NiB,N-doped BNNT_S had much higher adsorption energy and shorter binding distances than pure BNNT_S owning to chemisorptions of the PH₃ molecule. The obtained density of states (DOS) and frontier orbitals demonstrated that the orbital hybridization was obvious between the PH₃ molecule and Ni_B,N-doped BNNT_S. However, due to weak physisorption according to the total electron density maps, there was no evidence for hybridization between PH₃ molecule and pure BNNTS. It was shown that after doping of Ni atom, the primary symmetry of BNNT_S decreased which enhanced the chemical activity of BNNT_S towards PH₃ molecules. According to the obtained results, we highlight the high potential application of Ni_B,N-doped BNNT_S in the design and fabrication of PH₃ sensing devices.

     

Dynamic stereochemistry of erigeroside by measurement of 1H-1H and 13C-1H coupling constants

Erigeroside was extracted from Satureja khuzistanica Jamzad (Marzeh Khuzistani in Persian, family of lamiaceae), and (1)H, (13)C, (13)C{(1)H}, (1)H-(1)H COSY, HMQC and J-HMBC were obtained to identify this compound and determine a complete set of J-coupling constants ((1)J(C-H), (2)J(C-H), (3)J(C-H) and (3)J(H-H)) values within the exocyclic hydroxymethyl group (CH(2)OH) and anomeric center. In parallel, density functional theory (DFT) using B3LYP functional and split-valance 6-311++G** basis set has been used to optimized the structures and conformers of erigeroside. In all calculations solvent effects were considered using a polarized continuum (overlapping spheres) model (PCM). The dependencies of (1)J, (2)J and (3)J involving (1)H and (13)C on the C(5')-C(6') (omega), C(6')-O(6') (theta) and C(1')-O(1') (phi) torsion angles in erigeroside were computed using DFT method. Complete hyper surfaces for (1)J(C1',H1'), (2)J(C5',H6'R), (2)J(C5',H6'S), (2)J(C6',H5'), (3)J(C4',H6'R), (3)J(C4',H6'S) and (2)J(H6'R-H5'S) as well as (3)J(H5',H6'R) were obtained and used to derive Karplus equations to correlate these couplings to omega, theta and phi. These calculated J-couplings are in agreement with experimental values. These results confirm the reliability of DFT calculated coupling constants in aqueous solution.     

Preparation and evaluation of polymer-coated adsorbents for the expanded bed recovery of protein products from particulate feedstocks

A novel prototype polymer-coated adsorbent (PCA) has been developed for the effective expanded bed recovery of protein products from particulate feedstocks. The adsorbents were manufactured using the three-phase emulsification process by which the selected core phases (anion- and cation-exchangers and a custom-assembled pseudo-affinity adsorbent) were coated by an agarose gel. This new non-stick exterior coating acts as a sieve reducing the non-specific binding of cell and cell debris without diminution of selective capture of target protein from complex feedstocks such as whole microbial broths and cell disruptates. The new coated adsorbents were subjected to physical and hydrodynamical comparison with the performance of their uncoated adsorbents. Hydrodynamic characteristics (e.g. axial dispersion coefficient (D(axl)) and Bodenstein number (B(o))) of PCA demonstrated a marked robustness in the face of biomass loading disrupted yeast cells. In addition, each adsorbent was compared with its uncoated native form during the expanded bed adsorption of one of two intracellular proteins (i.e. glyceraldehyde 3-phosphate dehydrogenase and cytochrome c) from a 20% (ww/v) yeast disruptate. The performance parameters of efficiency of washing, purification factor, turbidity of the eluted product and protein recovery in all analysed cases were favourable to the coated materials. In particular, exploiting PCA reduced significantly undesirable adsorption of cells without significant loss of binding capacity for the target product. The generic application of such adsorbents and their potential for the recovery of target products from complex feedstock is discussed, whilst other application such as the subtractive purification of nanoparticles were detailed in our previous publication.     

Fabrication of poly(ϵ-caprolactone)/paclitaxel (core)/chitosan/zein/multi-walled carbon nanotubes/doxorubicin (shell) nanofibers against MCF-7 breast cancer

In the present study, paclitaxel (PTX), multi-walled carbon nanotubes (MWCNTs), and doxorubicin (DOX) have been simultaneously doped into the poly(ϵ-caprolactone) (PCL)/chitosan/zein core-shell nanofibers to increase its cytotoxicity for MCF-7 breast cancers killing. The physico-chemical properties of synthesized nanofibers were determined by scanning electron microscope, Fourier-transform infrared spectroscopy, tensile strength, and degradation rate determinations. The in vitro release studies demonstrated the sustained release of drugs from core-shell nanofibrous scaffold. The cytotoxicity and compatibility of core-shell nanofibers were investigated by their treating with MCF-7 breast cancer cells and L929 normal cells, respectively. PCL/PTX/chitosan/zein/MWCNTs/DOX core-shell nanofibers containing 1 wt% MWCNTs, 100 μg ml⁻¹ DOX and 100 μg ml⁻¹ PTX had a high biocompatibility with a 84% MCF-7 cancer cells killing. The in vivo studies revealed the synergic effects of MWCNTs and anticancer drugs on the tumor inhibition. This method could be considered as a new way for developing of MWCNTs loaded-nanofibers for cancer treatment in future.     

ATP‐Releasing Nucleotides: Linking DNA Synthesis to Luciferase Signaling

A new strategy is reported for the production of luminescence signals from DNA synthesis through the use of chimeric nucleoside tetraphosphate dimers in which ATP, rather than pyrophosphate, is the leaving group. ATP‐releasing nucleotides (ARNs) were synthesized as derivatives of the four canonical nucleotides. All four derivatives are good substrates for DNA polymerase, with K_m values averaging 13‐fold higher than those of natural dNTPs, and k_cat values within 1.5‐fold of those of native nucleotides. Importantly, ARNs were found to yield very little background signal with luciferase. DNA synthesis experiments show that the ATP byproduct can be harnessed to elicit a chemiluminescence signal in the presence of luciferase. When using a polymerase together with the chimeric nucleotides, target DNAs/RNAs trigger the release of stoichiometrically large quantities of ATP, thereby allowing sensitive isothermal luminescence detection of nucleic acids as diverse as phage DNAs and short miRNAs.