Molecularly imprinted polymer-based solid-phase extraction combined with molecularly imprinted polymer-based sensor for detection of uric acid

The development of an easy-to-use, rapid, robust and inexpensive technique is required which can measure the basal concentration of uric acid (UA) lower than 1.0 x 10(-7)M ( approximately 0.017 mgL(-1)) in biological samples to attend the problem of hypouricemia. In the present work an artificial receptor for UA, silica gel-bonded molecularly imprinted polymer (MIP), was used as a sorbent for molecularly imprinted solid-phase extraction (MISPE) in column chromatography. The use of a sensor based on a MIP-modified hanging mercury drop electrode (HMDE), as reported from our laboratory, could estimate UA with detection limit as low as 0.024 mgL(-1) under the optimized conditions of differential pulse, cathodic stripping voltammetric (DPCSV) measurement. However, in the current investigation, with the use of the combination of MISPE followed by detection with a MIP-based HMDE sensor, the minimum detectable concentration could go down to 0.0008 mgL(-1) (RSD=0.63%, S/N=3). The same MIP receptor for both MISPE and the corresponding sensor was able to enhance the preconcentration of analyte substantially so as to attain the desired level of sensitivity; and that to without any interference (cross-reactivity) from other structurally related analogues including the major interferent like ascorbic acid prevalent in the aqueous environment of biological samples.     

Engineering mono- and multi-valent inhibitors on a modular scaffold

Here we exploit the simple, ultra-stable, modular architecture of consensus-designed tetratricopeptide repeat proteins (CTPRs) to create a platform capable of displaying both single as well as multiple functions and with diverse programmable geometrical arrangements by grafting non-helical short linear binding motifs (SLiMs) onto the loops between adjacent repeats. As proof of concept, we built synthetic CTPRs to bind and inhibit the human tankyrase proteins (hTNKS), which play a key role in Wnt signaling and are upregulated in cancer. A series of mono-valent and multi-valent hTNKS binders was assembled. To fully exploit the modular scaffold and to further diversify the multi-valent geometry, we engineered the binding modules with two different formats, one monomeric and the other trimeric. We show that the designed proteins are stable, correctly folded and capable of binding to and inhibiting the cellular activity of hTNKS leading to downregulation of the Wnt pathway. Multivalency in both the CTPR protein arrays and the hTNKS target results in the formation of large macromolecular assemblies, which can be visualized both in vitro and in the cell. When delivered into the cell by nanoparticle encapsulation, the multivalent CTPR proteins displayed exceptional activity. They are able to inhibit Wnt signaling where small molecule inhibitors have failed to date. Our results point to the tremendous potential of the CTPR platform to exploit a range of SLiMs and assemble synthetic binding molecules with built-in multivalent capabilities and precise, pre-programmed geometries.     

Dielectric and electrical properties of a tungsten bronze tantalate ceramic

Using high temperature solid state reaction the polycrystalline sample of K₂Pb₂Dy₂W₂Ti₄Ta₄O₃₀ was prepared. Single-phase compound formation was confirmed by preliminary X-ray structural analysis. The surface morphology recorded by scanning electron microscope at room temperature exhibits a dense uniform grain distribution on the surface of the sample. Ferroelectricity in the material is confirmed by the variation of polarization with temperature. The temperature and frequency dependence of electrical parameters (impedance, modulus, conductivity, etc.) of the material exhibits a strong correlation with its microstructure (i.e., bulk, grain boundary, etc.) and electrical properties. A typical Arrhenius behavior was observed in the temperature dependence of dc conductivity. The nature of frequency dependence of ac conductivity obeys Jonscher's universal power law. The variation of current with temperature shows that the material has high pyroelectric coefficient and figure of merit, thus making it useful for pyroelectric sensors with working temperature upto 500 °C.     

Self-assembly of C60, SWNTs and few-layer graphene and their binary composites at the organic-aqueous interface

Self-assembly of C(60), single-walled carbon nanotubes (SWNTs) and few-layer graphene at the toluene-water interface has been investigated, starting with different concentrations of the nanocarbons in the organic phase and carrying out the assembly to different extents. Morphologies and structures of the films formed at the interface have been investigated by electron microscopy and other techniques. In the case of C(60), the films exhibit hcp and fcc structures depending on the starting concentration in the organic phase, the films being single crystalline under certain conditions. Self-assembly of the composites formed by pairs of nanocarbons (C(60)-SWNT, C(60)-few-layer graphene and SWNT-few-layer graphene) at the interface has been studied by electron microscopy. Raman spectroscopy and electronic absorption spectroscopy of the films formed at the interface have revealed the occurrence of charge-transfer interaction between SWNTs and C(60) as well as between few-layer graphene and C(60).     

A Novel Dialkylamino-Functionalized Chalcone,DML6, Inhibits Cervical Cancer Cell Proliferation,In Vitro,via Induction of Oxidative Stress,Intrinsic Apoptosis and Mitotic Catastrophe

In this study, we designed, synthesized and evaluated, in vitro, novel chalcone analogs containing dialkylamino pharmacophores in the cervical cancer cell line, OV2008. The compound, DML6 was selective and significantly decreased the proliferation of OV2008 and HeLa cells in sub-micromolar concentrations, compared to prostate, lung, colon, breast or human embryonic kidney cell line (HEK293). DML6, at 5 μM, arrested the OV2008 cells in the G2 phase. Furthermore, DML6, at 5 μM, increased the levels of reactive oxygen species and induced a collapse in the mitochondrial membrane potential, compared to OV2008 cells incubated with a vehicle. DML6, at 5 μM, induced intrinsic apoptosis by significantly (1) increasing the levels of the pro-apoptotic proteins, Bak and Bax, and (2) decreasing the levels of l the anti-apoptotic protein, Bcl-2, compared to cell incubated with a vehicle. Furthermore, DML6, at 5 and 20 μM, induced the cleavage of caspase-9, followed by subsequent cleavage of the executioner caspases, caspase-3 and caspase-7, which produced OV2008 cell death. Overall, our data suggest that DML6 is an apoptosis-inducing compound that should undergo further evaluation as a potential treatment for cervical cancer.     

Current Scenario of Poly (2,5-Benzimidazole) (ABPBI) as Prospective PEM for Application in HT-PEMFC

Abstract

In last two decades, acid doped polybenzimidazole as polymer electrolyte membrane (PEM) has been widely recognized and envisioned as “ideal” proton conducting materials for application in high temperature PEM fuel cell (HT-PEMFC). The majority of research and developmental work is mainly focused on poly (2,2´-m-phenylene-5,5´-bibenzimidazole), However, it is neither easy-processed nor inexpensive component of the respective family. On the other hand, among the various members belonging to benzimidazole family, poly (2,5-benzimidazole) is unique because it possesses a cost-attractive, single-step synthesis process, high extent of doping as well as good chemical and thermal stability. In the recent years this material has proved its potency in the earlier research. Thus this review puts special emphasis on poly (2,5-benzimidazole) and epitomizes the on-going breath-taking progress and achievements on the fabrication of poly (2,5-benzimidazole) based membranes. The write-up describes the effect of blending, cross-linking, ionic liquids and incorporation organic/inorganic nano-fillers. In addition, incorporating other protonic dopants such as heteropoly acids into the chain of poly (2,5-benzimidazole) molecular skeleton is also overviewed. Moreover, the critical interpretation of different causes responsible for earlier degradation and their effect towards the fabrication of high temperature membrane electrode assembly are visualized herein.

• Highlights

• Current developments and existing challenges of ABPBI in PEMFC have been reviewed.

• PEM Modification and addition of protonic dopants has been discussed.

• Proton migration, permeability, stability and reliability are thoroughly illustrated.

• Different ABPBI-based membranes and their performance are comparatively analyzed.

     

Development of Light‐Activated CRISPR Using Guide RNAs with Photocleavable Protectors

The ability to remotely trigger CRISPR/Cas9 activity would enable new strategies to study cellular events with greater precision and complexity. In this work, we have developed a method to photocage the activity of the guide RNA called “CRISPR‐plus” (CRISPR‐precise light‐mediated unveiling of sgRNAs). The photoactivation capability of our CRISPR‐plus method is compatible with the simultaneous targeting of multiple DNA sequences and supports numerous modifications that can enable guide RNA labeling for use in imaging and mechanistic investigations.     

The Binary Group 4 Azides [PPh4]2[Zr(N3)6] and [PPh4]2[Hf(N3)6]

The binary zirconium and hafnium polyazides [PPh₄]₂[M(N₃)₆] (M=Zr, Hf) were obtained in near quantitative yields from the corresponding metal fluorides MF₄ by fluoride–azide exchange reactions with Me₃SiN₃ in the presence of two equivalents of [PPh₄][N₃]. The novel polyazido compounds were characterized by their vibrational spectra and their X‐ray crystal structures. Both anion structures provide experimental evidence for near‐linear M‐N‐N coordination of metal azides. The species [M(N₃)₄], [M(N₃)₅]^? and [M(N₃)₆]^2? (M=Ti, Zr, Hf) were studied by quantum chemical calculations at the electronic structure density functional theory and MP2 levels.     

Fluoroaryl-substituted aminoalane dimers: syntheses and structures

Six dimeric aminoalanes of formula [Me(2)Al-mu-N(H)Ar(F)](2)(Ar(F)= 4-C(6)H(4)F (1), 2-C(6)H(4)F (2), 3,5-C(6)H(3)F(2)(3), 2,3,4,5-C(6)HF(4)(4), 2,3,5,6-C(6)HF(4)(5) and C(6)F(5)(6)) have been prepared by treatment of the appropriate fluoroaniline with AlMe(3) in toluene solution at 25 degrees C. The structures of 1-6 were determined by X-ray crystallography.