Two novel procedures of preparation for [Tc(CO)<Subscript>2</Subscript>(NO)]<Superscript>2+</Superscript>labeled by EHIDA and its biodistribution

To develop potential new Tc radiopharmaceuticals, a novel compound [^99mTc(CO)₂(NO)(EHIDA)]⁰ (EHIDA: 2,6-diethylphenylcarbamoylmethyliminodiacetic acid) has been prepared by reacting [^99mTc(CO)₃)(EHIDA)]⁻ with NOBF₄ both in water and acetonitrile. The conversion of [^99mTc(CO)₃)(EHIDA)]⁻ to [^99mTc(CO)₂(NO)(EHIDA)]⁰ was supported by TLC, HPLC and eletrophoresis. The radiochemical purity (more than 99%) was proved by TLC and HPLC. The biodistribution in mice demonstrated that [Tc(CO)₂(NO)(EHIDA)]⁰ showed higher uptake in blood, kidney and lung (15 min, blood: 19.24±2.95; kidney: 13.61±3.49; lung: 10.81±1.09.) but a lower uptake in liver (15 min, 5.73±0.74). The slower clearances (120 min, blood: 12.75±1.34; kidney: 13.61±3.49) from blood and kidney were also found. This research describes two methods for the conversion of [^99mTc(CO)₃]⁺ into [^99mTc(CO)₂)(NO)]²⁺ by using NOBF₄ as the source of NO⁺ both in organic solvent and water. The latter method offers the possibility to introduce the NO-group in high yield in water.     

The preparation and fluorescence properties of europium nanoparticles

A new structured metallic nanomaterial of europium nanoparticle was prepared using tannic acid as the reductive agent,and nanoeuropium protein conjugates were synthesized by the method of lipoic acid modification on the surface of nanoparticle,which opens a new field of application of lanthanides in nanotechniques.Their properties were also characterized by UV-vis absorption spectroscopy,transmission electron microscopy (TEM),and fluorescence spectroscopy.The europium nanoparticle and its protein conjugates solution were stable and water-soluble.The fluorescence intensity of the composite europium nanoparticles was significantly increased in the presence of trace protein,and was linear proportional to the concentration of proteins under optimum conditions.According to this,a fluorimetric method for the determination of protein was developed in this paper.     

A new three‐dimensional neutral framework of lanthanum oxalate: [La2(C2O4)3(DMF)(H2O)3]n

In the title complex, poly[triaquabis(dimethylformamide)di‐μ₃‐oxalato‐μ₂‐oxalato‐dilanthanum(III)], [La₂(C₂O₄)₃(C₃H₇NO)(H₂O)₃]_n, both La ions are coordinated by nine O atoms, forming slightly distorted tricapped trigonal prisms. The two La ions, the terminal water O atom, and the O and N atoms of the dimethylformamide molecule reside on twofold rotation axes, giving the two La‐centered coordination geometries twofold or pseudo‐twofold symmetries. The two oxalate ligands, one of which rests on a center of inversion at the mid‐point of the C—C bond, adopt different bridging modes, connecting with the La ions to form two types of lanthanide oxalate chains, i.e. anionic {[La(C₂O₄)₂(DMF)(H₂O)₂]ⁿ⁻}_n (DMF is dimethylformamide) and cationic zigzag {[La(C₂O₄)(H₂O)]ⁿ⁺}_n, respectively. Each zigzag cationic chain is linked to four adjacent anionic chains via the bridging oxalate anions, and each anionic chain connects with four zigzag cationic chains, constructing a three‐dimensional neutral framework.     

Preparative isolation and purification of lutein from the microalga chlorella vulgaris by high-speed counter-current chromatography

High-speed counter-current chromatography (HSCCC) was applied to the isolation and purification of lutein from microalgae. Analytical HSCCC was used for the preliminary selection of a suitable solvent system composed of n-hexane-ethanol-water (4:3:1, v/v). Using the above solvent system, preparative HSCCC was successfully performed yielding lutein at 98% purity from 200 mg of the crude extract in a one-step separation.     

A superoxide dismutase-modified electrode that detects superoxide ion

A superoxide dismutase (SOD)-modified electrode, in which SOD is oriented on the gold electrode via a self-assembled monolayer of cysteine so as to allow its direct electrode reaction, possesses a bi-directional electrocatalysis for both the oxidation of superoxide ion (O2-) to O2 and the reduction of O2- to H2O2 and functions as a third generation O2- biosensor.     

Kinetics of vesicle formation

 The kinetics of vesicle formation from a hydrotrope (sodium xylenesulfonate) solution of a surfactant (Laureth 4) is studied by the use of a stopped-flow apparatus combined with a dynamic light scattering device to determine vesicle size in the system. The hydrotrope system studied presents a system with a high surfactant solubilization combined with vesicle formation simply by dilution with water. The kinetic results show a single exponential decay time. The kinetic analysis indicates that the vesicles are formed from a molecular solution which resulted from the shear in the stopped-flow device and grow by monomeric association. Received: 1 October 1996 Accepted: 22 November 1996     

pH-sensitive polyelectrolyte complex gel microspheres composed of chitosan/sodium tripolyphosphate/dextran sulfate: swelling kinetics and drug delivery properties

Porous chitosan (CS) polyelectrolyte complex (PEC) hydrogel microspheres were prepared via either wet phase-inversion or ionotropic crosslinking with sodium tripolyphosphate (Na+ - TPP) and dextran sulfate (DS). The resulting microspheres were characterized using scanning electron microscopy (SEM) and elemental analysis (EA). The controlled release behavior of ibuprofen (IBU) from these microspheres was investigated. The PEC microspheres were about 700-950 microm in diameter with large pores and open porous structure. The CS/TPP/DS microspheres resisted hydrolysis in strong acid and biodegradation in enzymatic surroundings. The swelling kinetics for CS microspheres was close to Fickian diffusion, whereas those for CS/TPP and CS/TPP/DS were non-Fickian. Furthermore, the equilibrium water content (EWC) and water diffusion coefficient (D) increased with the pH of the media. The release profiles of IBU from CS/TPP/DS microspheres were slow in simulated gastric fluid (SGF, pH 1.4) over 3 h, but nearly all of the initial drug content was released in simulated intestinal fluid (SIF, pH 6.8) within 6 h after changing media. Overall the results demonstrated that CS/TPP/DS microspheres could successfully deliver a hydrophobic drug to the intestine without losing the drug in the stomach, and hence could be potential candidates as an orally administered drug delivery system.     

Cation-pi interactions with a model for the side chain of tryptophan: structures and absolute binding energies of alkali metal cation-indole complexes

Threshold collision-induced dissociation techniques are employed to determine bond dissociation energies (BDEs) of mono- and bis-complexes of alkali metal cations, Li+, Na+, K+, Rb+, and Cs+, with indole, C8H7N. The primary and lowest energy dissociation pathway in all cases is endothermic loss of an intact indole ligand. Sequential loss of a second indole ligand is observed at elevated energies for the bis-complexes. Density functional theory calculations at the B3LYP/6-31G level of theory are used to determine the structures, vibrational frequencies, and rotational constants of these complexes. Theoretical BDEs are determined from single point energy calculations at the MP2(full)/6-311+G(2d,2p) level using the B3LYP/6-31G* geometries. The agreement between theory and experiment is very good for all complexes except Li+ (C8H7N), where theory underestimates the strength of the binding. The trends in the BDEs of these alkali metal cation-indole complexes are compared with the analogous benzene and naphthalene complexes to examine the influence of the extended pi network and heteroatom on the strength of the cation-pi interaction. The Na+ and K+ binding affinities of benzene, phenol, and indole are also compared to those of the aromatic amino acids, phenylalanine, tyrosine, and tryptophan to elucidate the factors that contribute to the binding in complexes to the aromatic amino acids. The nature of the binding and trends in the BDEs of cation-pi complexes between alkali metal cations and benzene, phenol, and indole are examined to help understand nature's preference for engaging tryptophan over phenylalanine and tyrosine in cation-pi interactions in biological systems.     

Electrochemical Determination of Ascorbic Acid at γ-MnO<Subscript>2</Subscript> Modified Carbon Black Microelectrodes

A carbon black microelectrode modified by -MnO₂ has been prepared. The electrocatalytical oxidation of ascorbic acid (AA) at this microelectrode was investigated. The 2nd-order linear scan voltammograms of AA are recorded from –0.5 to 0.5V (vs. SCE). The relationship between the oxidation peak current of AA and its concentration in the range of 1.0×10^–64.0×10^–3molL^–1 is linear. The detection limit (3) was found to be 6.0×10^–7molL^–1. Also, the determination of AA in samples is evaluated, and the results are satisfactory.     

Linear combination of concomitants of order statistics with application to testing and estimation

Summary Let (X ₁,Y ₁), (X ₂,Y ₂),…, (X _n,Y _n) be i.i.d. as (X, Y). TheY-variate paired with therth orderedX-variateX _rn is denoted byY _rn and terms the concomitant of therth order statistic. Statistics of the form are considered. The asymptotic normality ofT _n is established. The asymptotic results are used to test univariate and bivariate normality, to test independence and linearity ofX andY, and to estimate regression coefficient based on complete and censored samples.