Unraveling the Electrical and Magnetic Properties of Layered Conductive Metal-Organic Framework With Atomic Precision.

This paper describes structural elucidation of a layered conductive metal-organic framework (MOF) material Cu3 (C6 O6 )2 by microcrystal electron diffraction with sub-angstrom precision. This insight enables the first identification of an unusual π-stacking interaction in a layered MOF material characterized by an extremely short (2.73 Å) close packing of the ligand arising from pancake bonding and ordered water clusters within pores. Band structure analysis suggests semiconductive properties of the MOF, which are likely related to the localized nature of pancake bonds and the formation of a singlet dimer of the ligand. The spin of CuII within the Kagomé arrangement dominates the paramagnetism of the MOF, leading to strong geometrical magnetic frustration.

Protein capture and SERS detection on multiwavelength rainbow-trapping width-graded nano-gratings.

Surface-enhanced Raman scattering (SERS) substrates with multiwavelength rainbow-trapping properties hold the potential for a one-size-fits-all platform for rapid and multiplexed disease detection. We present the first report on the utilization of rainbow-trapping width-graded nano-gratings, a new class of chirped metamaterials, to detect protein biomarkers. Using cytochrome c (Cc), a charged analyte with inherent difficulty in adsorbing onto sputtered silver films, we investigated methods of binding Cc on the silver nano-grating in order to improve the SERS signal strength at both 532 and 638 nm excitation. Cc was not detectable on the Ag nano-gratings without surface functionalization at 1µM concentration. Upon charge reversal functionalization of the Ag nano-gratings, 1µM Cc was detectable albeit not reliably. By further crosslinking 1µM Cc to the functionalized Ag nano-gratings, the analyte-capture detection scheme greatly improved the SERS signal strength and reliability at both excitation wavelengths and allowed for quantification of their coefficients of variation with values down to 27%.

High performance ionic-liquid-gated air doped diamond field-effect transistors.

We report successful fabrication of high performance ion-gated field-effect transistors (FETs) on hydrogenated diamond surface. Investigations on the hydrogen (H)-terminated diamond by Hall effect measurements shows Hall mobility as high as ∼200 cm2 V-1 s-1. In addition we demonstrate a rapid fabrication scheme for achieving stable high performance devices useful for determining optimal growth and fabrication conditions. We achieved H-termination using hydrogen plasma treatment with a sheet resistivity as low as ∼1.3 kΩ/sq. Conductivity through the FET channel is studied as a function of bias voltage on the liquid ion-gated electrode from -3.0 to 1.5 V. Stability of the H-terminated diamond surface was studied by varying the substrate temperature up to 350 °C. It was demonstrated that the sheet resistance and carrier densities remain stable over 3 weeks in ambient air atmosphere even at substrate temperatures up to 350 °C, whereas increasing temperature beyond this limit has effected hydrogenation. This study opens new avenues for carrying out fundamental research on diamond FET devices with ease of fabrication and high throughput.

Optimized oxygen deprived low temperature sputtered WO3 thin films for crystalline structures.

We report a detailed analysis on the effects of processing parameters for sputtered tungsten trioxide (WO3) thin nanoscale films on their structural, vibrational and electrical properties. The research aims to understand the fundamental aspects of WO3 sputtering at relatively low temperatures and in an oxygen deprived environment targeting applications of temperature and oxygen sensitive substrates. Structural analysis indicates that films deposited at room temperature, or substrate temperatures at or below 400 °C with low oxygen partial pressure are amorphous. Crystallization of the films was observed with distinct Raman peaks when the films were annealed at 300 °C or above using rapid thermal annealing for 10 min. Films revealed monoclinic phases of WO3 with the presence of W-O-W stretching, bending and lattice vibrational modes in the Raman spectra. Interestingly, a change of transport behavior from insulating to semiconducting was observed for as deposited films on post annealing. Annealed films revealed stoichiometric WO3 phases with no external defects detected. The present study adopts a route to intercalate WO3 in a variety of applications from electrochromic coloration to a nanocrystalline thin film for electronic devices sensitive to higher temperatures and gas flow in the sputtering system.

Indium Dopant Concentration Effects on Zinc Oxide Nanowires.

We report in detail the effects of varying the concentration of indium as a dopant in ZnO on the structural, vibrational, and optical properties of ZnO nanowires. A highly versatile route to dope zinc oxide nanowires by using vapor-liquid-solid growth is employed. It is observed that the ratio of indium in ZnO reactant has a large impact on properties of indium-doped ZnO nanowires. Lower indium concentration reveals better transparency while higher concentrations of indium shows segregation of indium-rich domains within the doped nanocrystals. Photoluminescence measurements demonstrated band gap tuning and a smaller UV to deep emission ratio for doped nanowires. Phonon vibrational modes along with origin of observed anomalous vibrational modes induced due to indium incorporation in ZnO are discussed. An average transmittance of more than 90% is observed for a wide range of spectra in both visible and near-IR regions as compared with indium tin oxide. The lowest resistivity of 1.2 × 10-3 Ω·cm was achieved for ZnO films doped with 7% indium oxide. These dramatically superior optical and electrical properties make it a superior candidate for various technological applications.

Antioxidant activity of an ethnobotanically important plant Quisqualis indica Linn.

The antioxidant potential of leaf, stem, root and flower extracts of Quisqualis indica Linn. was assessed to verify its ethnopharmacological importance. Both polar and non-polar solvents like n-hexane, chloroform, ethanol and distilled water were used to obtain crude extracts. The chloroform extract of leaves showed the maximum %age yield, i.e. 27.3% while the n-hexane extract of stem showed the minimum yield, i.e. 0.2%. Five activities including DPPH free radical scavenging activity, ABTS+ assay, Total flavonoid components (TFC), Total phenolic components (TPC) and Metal chelating Assay (MC) were employed to evaluate the antioxidant activity of the plant. The ethanol extract of inflorescence of the plant displayed most elevated DPPH potential, i.e. 452.11%. Aqueous extract of root had highest value of TEAC i.e., 7.4515 mmol. The aqueous extract of flower displayed the highest level of phenolic contents with the value of 35 in terms of GAE mg/mL. On the other hand, the chloroform extract had the highest % bound iron value of 128 and the aqueous extract of flower showed a high concentration of Flavonoids having the value 347.65mg/l of Quercetin. It has been inferred that all parts of Quisqualis indica L. possess good antioxidant potential. Differents parts showed different antioxidant potentials hence they can be used as curative agents against human and animal ailments.

Modulation of voltage-gated conductances of retinal horizontal cells by UV-excited TiO2 nanoparticles.

This study examines the ability of optically-excited titanium dioxide nanoparticles to influence voltage-gated ion channels in retinal horizontal cells. Voltage clamp recordings were obtained in the presence and absence of TiO2 and ultraviolet laser excitation. Significant current changes were observed in response to UV light, particularly in the -40 mV to +40 mV region where voltage-gated Na+ and K+ channels have the highest conductance. Cells in proximity to UV-excited TiO2 exhibited a left-shift in the current-voltage relation of around 10 mV in the activation of Na+ currents. These trends were not observed in control experiments where cells were excited with UV light without being exposed to TiO2. Electrostatic force microscopy confirmed that electric fields can be induced in TiO2 with UV light. Simulations using the Hodgkin-Huxley model yielded results which agreed with the experimental data and showed the I-V characteristics of individual ion channels in the presence of UV-excited TiO2.

Phytochemical screening, GC-MS analysis and in vitro antioxidant activity of pollen of Centella asiatica (Linn) urban a traditional medicinal plant.

In the present study the crude extracts of pollen of Centella asiatica (Linn.) Urban were explored for their antioxidant potential using Ferric Reducing Power, Metal Chelating Activity and Trolox Equivalent Antioxidant Capacity assays. In crude extracts of pollen antioxidant components were initially extracted in methanol and further fractionated in solvents of different polarity, such as n-Hexane, Chloroform, Ethyl Acetate and Water exhibited reasonable antioxidant activity. The extract was found to contain large amounts of phenolic and flavonoid contents ranged from 143-1155 mg/l of gallic acid equivalent (GAE) and 911-2488 mg/l of quercetin (QE) respectively. Moreover, Super oxide Anion Radical Scavenging Activity and GS-MS analysis were also carried out.

In vitro antioxidant potential and free radical scavenging activity of various extracts of pollen of Typha domigensis Pers.

Antioxidant potential of the pollen of Typha domigensis Pers. using Ferric Reducing ower, Metal Chelating Activity and Trolox Equivalent Antioxidant Capacity (TEAC) assays has been carried out in the current research work. The antioxidant components were initially extracted from the pollen in methanol and were further fractionated in solvents of different polarity such as n-Hexane, Chloroform, Ethyl Acetate and Water. Methanol extract which was found to have high reducing power, total phenolic contents with high metal chelating activity, has considerable prospective to utilize as a natural antioxidant and be capable to link with the total phenolic contents of plant.

N-[4-(4-Chloro-benzene-sulfonamido)-phenyl-sulfon-yl]acetamide.

In the title compound, C(14)H(13)ClN(2)O(5)S(2), the dihedral angles between the central benzene ring and the pendant chloro-benzene ring and the N-acetyl group are 82.35 (5) and 79.71 (6)°, respectively, and the overall conformation of the mol-ecule approximates to a U shape. Both the C-S-N-C conformations are gauche, but with opposite senses [torsion angles = -59.29 (15) and 63.68 (16)°]. An intra-molecular C-H⋯O inter-action generates an S(6) ring. In the crystal, inversion dimers linked by pairs of N-H⋯O hydrogen bonds generate R(2) (2)(20) loops. A second N-H⋯O hydrogen bond links the dimers into (101) layers.

N-[4-(Ethyl-sulfamo-yl)phen-yl]acetamide.

The title compound, C(10)H(14)N(2)O(3)S, crystallized with two mol-ecules (A and B) in the asymmetric unit. The terminal methyl group of the ethyl-sulfonamide moiety in mol-ecule B is disordered over two sets of sites with an occupancy ratio of 0.61 (1):0.39 (1). Both mol-ecules have L-shaped conformations. In mol-ecule A, the dihedral angles between the benzene ring and its ethyl-sulfonamide and methyl-amide substituents are 83.5 (3) and 13.34 (18)°, respectively. Equivalent values for mol-ecule B are 87.9 (3) and 6.32 (16)°, respectively. The C-S-N-C torsion angles are 66.5 (3)° for A and -64.4 (3)° for B, indicating similar twists about the S-N bonds, but in opposite senses. In the crystal, the A mol-ecules are linked by pairs of N(s)-H⋯O (s = sulfonamide) hydrogen bonds, generating inversion dimers containing R(2) (2)(8) rings, while the B mol-ecules are linked by N(s)-H⋯O hydrogen bonds into C(10) [100] chains. Finally, N(a)-H⋯O (a = amide) hydrogen bonds link the A-mol-ecule dimers and B-mol-ecule chains into a three-dimensional network.

Biomedical Applications of Quantum Dots, Nucleic Acid-Based Aptamers, and Nanostructures in Biosensors.

This review is a survey of the biomedical applications of semiconductor quantum dots, nucleic acid-based aptamers, and nanosensors as molecular biosensors. It focuses on the detection of analytes in biomedical applications using (1) advances in molecular beacons incorporating semiconductor quantum dots and nanoscale quenching elements; (2) aptamer-based nanosensors on a variety of platforms, including graphene; (3) Raman scattering and surface-enhanced Raman scattering (SERS) using nanostructures for enhanced SERS spectra of biomolecules, including aptamers; and (4) the electrical and optical properties of nanostructures incorporated into molecular beacons and aptamer-based nanosensors. Research done at the University of Illinois at Chicago (UIC) is highlighted throughout since it emphasizes the specific approaches taken by the bioengineering department at UIC.

A Graphene and Aptamer Based Liquid Gated FET-Like Electrochemical Biosensor to Detect Adenosine Triphosphate.

Here we report successful demonstration of a FET-like electrochemical nano-biosensor to accurately detect ultralow concentrations of adenosine triphosphate. As a 2D material, graphene is a promising candidate due to its large surface area, biocompatibility, and demonstrated surface binding chemistries and has been employed as the conducting channel. A short 20-base DNA aptamer is used as the sensing element to ensure that the interaction between the analyte and the aptamer occurs within the Debye length of the electrolyte (PBS). Significant increase in the drain current with progressive addition of ATP is observed whereas for control experiments, no distinct change in the drain current occurs. The sensor is found to be highly sensitive in the nanomolar (nM) to micromolar ( µM) range with a high sensitivity of 2.55 µA (mM) (-1), a detection limit as low as 10 pM, and it has potential application in medical and biological settings to detect low traces of ATP. This simplistic design strategy can be further extended to efficiently detect a broad range of other target analytes.

Detection of Interferon gamma using graphene and aptamer based FET-like electrochemical biosensor.

One of the primary goals in the scientific community is the specific detection of proteins for the medical diagnostics and biomedical applications. Interferon-gamma (IFN-γ) is associated with the tuberculosis susceptibility, which is one of the major health problems globally. We have therefore developed a DNA aptamer-based electrochemical biosensor that is used for the detection of IFN-γ with high selectivity and sensitivity. A graphene monolayer-based FET-like structure is incorporated on a PDMS substrate with the IFN-γ aptamer attached to graphene. Addition of target molecule induces a change in the charge distribution in the electrolyte, resulting in increase in electron transfer efficiency that was actively sensed by monitoring the change in current from the device. Change in current appears to be highly sensitive to the IFN-γ concentrations ranging from nanomolar (nM) to micromolar (µM) range. The detection limit of our IFN-γ electrochemical biosensor is found to be 83 pM. Immobilization of aptamer on graphene surface is verified using unique structural approach by Atomic Force Microscopy. Such simple and sensitive electrochemical biosensor has potential applications in infectious disease monitoring, immunology and cancer research in the future.