Quantification of Doxorubicin in Pegylated Polymer Micelles in Rat Plasma by Methanol Precipitation�CUltrasonic Emulsion Breaking Method and UPLC�CMS�CMS

This study established a new methanol precipitation?Cultrasonic emulsion breaking method for extraction of doxorubicin from polymeric micelles and developed a UPLC?CMS/MS method for the determination of doxorubicin in rat plasma. The emulsion breaking efficiency of methanol is up to 99.2%. The plasma samples were analyzed by UPLC/MS/MS using positive electrospray ionization mode in the multiple-reaction monitoring (MRM) mode. The calibration curves were linear over the range 5?C1,000 ng mL^?1 with the lower limit of quantification of 5 ng mL^?1. The intra- and inter-day precisions of QC samples were all <10.0%. The chromatographic separation was 2.5 min. The developed method was successfully applied to a pharmacokinetic study of doxorubicin in rats following intravenous administration.     

Preparation of molecularly imprinted polymer by surface imprinting technique and its performance for adsorption of dibenzothiophene

The novel surface imprinted polymer composites (MIP/K(2)Ti(4)O(9)) were prepared using dibenzothiophene (DBT) as the template, 4-vinylpyridine as the functional monomer and potassium tetratitanate whisker (K(2)Ti(4)O(9)) as the carrier. The synthetic product was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. Parameters influencing DBT adsorption such as contact time, temperature and DBT initial concentration were investigated. The adsorption kinetics were evaluated with the pseudo-first-order and pseudo-second-order models, and the adsorption isotherms were fitted by Langmuir and Freundlich models. Selectivity experiments showed that MIP/K(2)Ti(4)O(9) exhibited excellent recognition capacity and binding affinity to DBT compared with the comparative substrates. MIP/K(2)Ti(4)O(9) could also be easily regenerated and reused ten times with only about 20% loss of adsorption capacity.     

Sensitive determination of ATP using a carbon paste electrode modified with a carboxyl functionalized ionic liquid

We report on a new electrode for the determination of adenosine-5??-triphosphate (ATP). It is based on modified carbon paste electrode that contains an ionic liquid (IL) as the binder. The electrode shows strong electrocatalytic oxidative activity towards ATP at pH 4.5 in giving a well-defined single oxidation peak. The oxidation reaction is adsorption-controlled and due to the presence of the highly conductive IL. The electron transfer rate constant was calculated to be 2.04×10^?C3 s^?C1, and the surface coverage is 1.11×10^?C10 mol cm^?C2. Under the selected conditions, the oxidation peak current changes linearly with the concentration of ATP in the range from 5.0 to 1000???mol L^?1 and a detection limit of 1.67???mol L^?1 (3???) as determined by differential pulse voltammetry. The method displays good selectivity and was applied to the determination of ATP injection samples with satisfactory results.

Hippocampal metabolomics reveals 2,3,7,8-tetrachlorodibenzo-p-dioxin toxicity associated with ageing in Sprague-Dawley rats

Metabolomics, the exponentially developing technique, could provide a systemic mapping in toxicology by directly measuring small molecular metabolites. 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) was found to be neurotoxic in mammalian animals. In this study, we employed liquid chromatography/quadrupole time-of-flight mass spectrometry for non-targeted analysis of metabolic profiling in hippocampal sample sets of the rats exposed to TCDD. Hippocampal metabolome from different ages of the healthy rats (4-week, 12-week and 20-week) was also deciphered. The relationship between the two tested cases was unlocked to delineate TCDD toxicity associated with ageing. Tandem mass spectrometry fragmentation in conjunction with metabolic database searching and compared to authentic standards was utilized for metabolite identification. As a consequence, the reduced levels of phenylalanine and leucine/isoleucine as well as the up-regulation of inosine and hypoxanthine were highlighted for understanding of TCDD toxicity related to age in rats and the trajectory was depicted by principal components analysis.     

Time resolved flow-field measurements of a turbulent mixing layer over a rectangular cavity

High Reynolds number, low Mach number, turbulent shear flow past a rectangular, shallow cavity has been experimentally investigated with the use of dual-camera cinematographic particle image velocimetry (CPIV). The CPIV had a 3 kHz sampling rate, which was sufficient to monitor the time evolution of large-scale vortices as they formed, evolved downstream and impinged on the downstream cavity wall. The time-averaged flow properties (velocity and vorticity fields, streamwise velocity profiles and momentum and vorticity thickness) were in agreement with previous cavity flow studies under similar operating conditions. The time-resolved results show that the separated shear layer quickly rolled-up and formed eddies immediately downstream of the separation point. The vortices convect downstream at approximately half the free-stream speed. Vorticity strength intermittency as the structures approach the downstream edge suggests an increase in the three-dimensionality of the flow. Time-resolved correlations reveal that the in-plane coherence of the vortices decays within 2–3 structure diameters, and quasi-periodic flow features are present with a vortex passage frequency of ~1 kHz. The power spectra of the vertical velocity fluctuations within the shear layer revealed a peak at a non-dimensional frequency corresponding to that predicted using linear, inviscid instability theory.     

Nonresonant and resonant mode-specific intermolecular vibrational energy transfers in electrolyte aqueous solutions

The donor/acceptor energy mismatch and vibrational coupling strength dependences of interionic vibrational energy transfer kinetics in electrolyte aqueous solutions were investigated with ultrafast multiple-dimensional vibrational spectroscopy. An analytical equation derived from the Fermi's Golden rule that correlates molecular structural parameters and vibrational energy transfer kinetics was found to be able to describe the intermolecular mode specific vibrational energy transfer. Under the assumption of the dipole-dipole approximation, the distance between anions in the aqueous solutions was obtained from the vibrational energy transfer measurements, confirmed with measurements on the corresponding crystalline samples. The result demonstrates that the mode-specific vibrational energy transfer method holds promise as an angstrom molecular ruler.     

Sandwich-type tetrakis(phthalocyaninato) dysprosium-cadmium quadruple-decker SMM

Homoleptic tetrakis[2,3,9,10,16,17,23,24-octa(butyloxy)phthalocyaninato] dysprosium-cadmium quadruple-decker complex 1 was isolated in relatively good yield of 43% from a simple one-pot reaction. This compound represents the first sandwich-type tetrakis(phthalocyaninato) rare earth-cadmium quadruple-decker SMM that has been structurally characterized.     

Mixed (phthalocyaninato)(porphyrinato) heterometal complexes with sandwich quadruple-decker molecular structure

Two novel mixed (phthalocyaninato)(porphyrinato) rare-earth and cadmium heterometal complexes have been fabricated in one-pot reaction and their sandwich quadruple-decker nature is unambiguously revealed by X-ray single crystal analysis.     

Shape separation of colloidal gold nanoparticles through salt-triggered selective precipitation

Highly effective separation of colloidal gold nanorods/nanoplates from co-produced isotropic nanoparticles has been achieved by selective precipitation triggered by salt.     

Study on the structural changes of bovine serum albumin with effects on polydatin binding by a multitechnique approach

Polydatin is a traditional Chinese medicine which shows effective biological activity as antimicrobial and antiviral agent. The secondary structure changes of bovine serum albumin (BSA) were investigated by the methods of Fourier transform infrared spectroscopy (FT-IR), circular dichroism (CD) and Raman spectroscopy. The experimental results indicated that polydatin changed the secondary structure of BSA. The presence of polydatin decreased α-helix content of BSA. The conformations of disulfide bridges and the microenvironment of Tyr, Trp residues were also changed.