Biopolymer-assisted self-assembly of ZnO nanoarchitectures from nanorods

We have investigated three-dimensional (3-D) architectures–microspheres and radial structures–based on biopolymer-assisted self-assembly from one-dimensional ZnO nanorods. The developed method is simple, rapid and cost-effective and can be used for self-assembly of different complex superstructures. A possible model of 3-D architectures self-assembled with biopolymer assistance is presented using minimum energy considerations. Scanning electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, transmission electron microscopy, micro–Raman spectroscopy and cathode luminescence investigations show that the novel 3-D architectures are built from high-purity ZnO nanorods with a wurtzite structure. The resulting radial structures show an intense ultraviolet (UV) cathode luminescence emission suggesting applications as UV light emitting diodes or lasers. Their structural characteristics endow them with a broad area of applications and offer a possibility to be used as fundamental low-dimensional building units. These building units open opportunities for the self-assembly of multifunctional nanostructured systems with applications in bioscience and nanomedicine, electronics and photonics.     

EBC-232 and 323: A Structural Conundrum Necessitating Unification of Five In Silico Prediction and Elucidation Methods

Structurally unique halimanes EBC-232 and EBC-323, isolated from the Australian rainforest plant Croton insularis, proved considerably difficult to elucidate. The two diastereomers, which consist an unusual oxo-6,7-spiro ring system fused to a dihydrofuran, were solved by unification and consultation of five in silico NMR elucidation and prediction methods [i.e., ACDLabs, olefin strain energy (OSE), DP4, DU8+ and TD DFT CD]. Structure elucidation challenges of this nature are prime test case examples for empowering future AI learning in structure elucidation.     

Catalytic Chemosensing Assay for Selective Detection of Methyl Parathion Organophosphate Pesticide

Herein, a catalytic chemosensing assay (CCA), based on a bimetallic complex, [Ru^II(bpy)₂(CN)₂]₂(Cu^II)₂ (bpy=2,2′-bipyridine), is described. This complex integrates a task-specific catalyst (Cu^I-catalyst) and a signaling unit ([Ru^II(bpy)₂(CN)₂]) to specifically hydrolyze methyl parathion, a highly toxic organophosphate (OP) pesticide. The bimetallic complex catalyzed the hydrolysis of the phosphate ester to generate o,o-dimethyl thiophosphate (DTP) anion and 4-nitrophenolate. Intrinsically, 4-nitrophenolate absorbed UV/Vis light at λ_max=400 nm, creating the first level of the chemosensing signal. DTP interacted with the original complex to displace the chromophore, [Ru^II(bpy)₂(CN)₂], which was monitored by spectrofluorometry; this was classified as the second level of chemosensing signal. By integrating both spectroscopic and spectrofluorometric signals with a simple AND logic gate, only methyl parathion was able to provide a positive response. Other aromatic and aliphatic OP pesticides (diazinon, fenthion, meviphos, terbufos, and phosalone) and 4-nitrophenyl acetate provided negative responses. Furthermore, owing to the metal-catalyzed hydrolysis of methyl parathion, the CCA system led to the detoxification of the pesticide. The CCA system also demonstrated its catalytic chemosensing properties in the detection of methyl parathion in real samples, including tap water, river water, and underground water.     

Phase transitions in lysozyme solutions characterized by differential scanning calorimetry

The detailed understanding of the structure of biological macromolecules reveals their functions and is thus important in the design of new medicines and for engineering molecules with improved properties for industrial applications. However, obtaining high-quality crystals of proteins for determining structures is still quite difficult in general, and successful protein crystallization remains largely empirical and operator-dependent. In this work, a microcalorimetric technique has been utilized to investigate liquid-liquid phase separation through measuring the cloud-point temperature T^cloud for high supersaturated lysozyme solution, and the structure formation of lysozyme solution at low concentration. Pronounced heat-flow curves dependent on solution conditions during cooling process have been obtained and analyzed. The implications of calorimetric results are (i) as to lysozyme solution at low concentration, aggregates form and grow into clusters with the increase of supersaturation in the absence of glycerol, while three-dimensional network instead of aggregates maybe form in the presence of glycerol; (ii) with respect to concentrated lysozyme solution, the cloud-point temperature increases monotonically with the concentration of sodium chloride, and is decresed when glycerol is added as additive.     

N-heterocycle chelated oxomolybdenum(VI and V) complexes with bidentate citrate

A 1,10-phenanthroline (phen) chelated molybdenum(VI) citrate, [(MoO2)2O(H2cit)(phen)(H2O)2] x H2O (1) (H4cit = citric acid), is isolated from the reaction of citric acid, ammonium molybdate and phen in acidic media (pH 0.5-1.0). A citrato oxomolybdenum(V) complex, [(MoO)2O(H2cit)2(bpy)2] x 4H2O (2), is synthesized by the reduction of citrato molybdate with hydrazine hydrochloride in the presence of 2,2'-bipyridine (bpy), and a monomeric molybdenum(VI) citrate [MoO2(H2cit)(bpy)] x H2O (6) is also isolated and characterized structurally. The citrate ligand in the three neutral compounds uses the alpha-alkoxy and alpha-carboxy groups to chelate as a bidentate leaving the two beta-carboxylic acid groups free, that is different from the tridentate chelated mode in the citrato molybdate(VI and V) complexes. 1 and in solution show obvious dissociation based on 13C NMR studies.     

Purification and Characterization of the Catalytic Domain of Protein Tyrosine Phosphatase SHP-1 and the Preparation of Anti-ΔSHP-1 Antibodies

This study is focused on the expression of an SH2 domain-truncated form of protein tyrosine phosphatase SHP-1（designated ΔSHP-1） and the preparation of its polyclonal antibodies. A cDNA fragment encoding ΔSHP-1 was amplified by PCR and then cloned into the pT7 expression vector. The recombinant pT7-ΔSHP-1 plasmid was used to transform Rosetta（DE3） E. coli cells. ΔSHP-1 was distributed in the exclusion body of E. coli cell extracts and was purified through a two-column chromatographic procedure. The purified enzyme exhibited an expected molecular weight on SDS-gels and HPLC gel filtration columns. It possesses robust tyrosine phosphatase activity and shows typical enzymatic characteristics of classic tyrosine phosphatases. To generate polyclonal anti-ΔSHP-1 antibodies, purified recombinant ΔSHP-1 was used to immunize a rabbit. The resultant anti-serum was subjected to purification on ΔSHP-1 antigen affinity chromatography. The purified polyclonal antibody displayed a high sensitivity and specificity toward ΔSHP-1. This study thus provides the essential materials for further investigating the biological function and pathological implication of SHP-1 and screening the inhibitors and activators of the enzyme for therapeutic drug development.     

An ab initio study of the low-lying electronic states of YO2 and Franck-Condon simulation of the first photodetachment band of YO2(-)

A variety of density functional theory and ab initio methods, including B3LYP, B98, BP86, CASSCF, CASSCF/RS2, CASSCF/MRCI, BD, BD(T), and CCSD(T), with ECP basis sets of up to the quintuple-zeta quality for Y, have been employed to study the X(2)B2 state of YO2 and the X(1)A1 state of YO2(-). Providing that the Y 4s(2)4p(6) outer-core electrons are included in the correlation treatment, the RCCSD(T) method gives the most consistent results and is concluded to be the most reliable and practical computational method for YO2 and YO2(-). In addition, RCCSD(T) potential energy functions (PEFs) of the X(2)B2 state of YO2 and the X(1)A1 state of YO2(-) were computed, employing the ECP28MDF_aug-cc-pwCVTZ and aug-cc-pVTZ basis sets for Y and O, respectively. Franck-Condon factors, which include allowance for Duschinsky rotation and anharmonicity, were calculated using the computed RCCSD(T) PEFs and were used to simulate the first photodetachment band of YO2(-). The simulated spectrum matches very well with the corresponding experimental 355 nm photodetachment spectrum of Wu, H.; Wang, L.-S. J. Phys. Chem. A 1998, 102, 9129, confirming the reliability of the RCCSD(T) PEFs used. Further calculations on low-lying electronic states of YO2 gave T(e)'s and T(vert)'s of the A(2)A1, B(2)B1, and C(2)A2 states of YO2, as well as EAs and VDEs to these states from the X(1)A1 state of YO2(-). On the basis of the ab initio VDEs obtained in the present study, previous assignments of the second and third photodetachment bands of YO2(-) have been revised.     

Morphological control of synthesis and anomalous magnetic properties of 3-D branched Pt nanoparticles

Morphology-controllable platinum nanostructures could be obtained by modulating the growth kinetics in oleylamine. The nanostructures evolve from spherical particles to branched networks with decreasing reaction temperature, and the complexity of the branched-network nanostructures increases with the extended reaction period. Size-dependent magnetic properties and enhanced ferromagnetism in dodecanethiol-capped Pt branched nanostructures indicate that the permanent magnetic moments are probably introduced by broken symmetry and charge transfer because charge transfers more effectively from dodecanethiol than from oleylamine.     

Engineering inorganic hybrid nanoparticles: tuning combination fashions of gold, platinum, and iron oxide

Multistep colloidal chemical routes were employed to synthesize Pt/Au, Pt/iron oxide (IO), and Au/Pt/IO hybrid nanoparticles (NPs). The starting templates, Pt NPs, were synthesized by controlling the decomposition kinetics of platinum acetylacetonate in oleylamine. The morphologies of binary metal Pt/Au hybrid NPs were modulated by controllable attachment of Au nanoscale domains to Pt templates. Similarly, Pt/IO and Au/Pt/IO hybrid NPs were fabricated by the controllable attachment of Fe to the Pt or Pt/Au template NPs. The noble metal domains of as-prepared hybrid NPs had face center cubic crystal structures and did not alloy, as verified by high resolution transmission electron microscopy and X-ray diffraction spectrometry. X-ray diffraction spectrometry study indicates that the IO domains in the as-prepared NPs have a spinel structure. UV-vis study of binary metal Pt/Au hybrid NPs revealed that they have a characteristic plasmon resonance around 525 nm, while dumbbell-like Au/Pt/IO NPs had a plasmon resonance around 600 nm. Furthermore, magnetism study of the binary Pt-IO NPs clearly indicated that the interfacial interactions between Pt and IO domains could result in a shift of the blocking temperature.