Incorporation and release behavior of amitriptylene in core-shell-corona type triblock copolymer micelles

A cationic antidepressant drug, amitriptylene (AMT), was successfully incorporated into core-shell-corona micelles of poly[styrene-b-sodium 2-(acrylamido)-2-methyl-1-propanesulfonate-b-ethylene oxide] (PS-b-PAMPS-b-PEO). Zeta-potential measurements revealed that both electrostatic and hydrophobic interactions contributed to the binding of the drug to the polymer. The AMT/PS-b-PAMPS-b-PEO nanocomplexes were characterized by dynamic light scattering, scanning electron microscopy, and transmission electron microscopy. The hydrodynamic diameter of the AMT loaded nanocomplexes decreased from 80 to 40nm depending on the amount of the drug loaded on the polymer. This is attributed to the cancellation of the negative charge of the PAMPS group by the cationic drug. The AMT/PS-b-PAMPS-b-PEO nanocomplexes were stable in aqueous solution exhibiting no aggregation or no precipitation for several months. Release of the AMT from the nanocomplexes was investigated in vitro in salt-free and 0.1M NaCl solutions. The drug was released faster in the 0.1M NaCl solution than in the salt-free solution. This is due to the shielding effect of the salt on the electrostatic interaction. However, in both cases, the drug release mainly occurs by the Fickian diffusion mechanism.     

Facile discrimination of aldose enantiomers by reversed-phase HPLC

One-pot reactions of aldoses with L-cysteine methyl ester and o-tolyl isothiocyanate yielded methyl 2-(polyhydroxyalkyl)-3-(o-tolylthiocarbamoyl)-thiazolidine-4(R)-carboxylates. Direct HPLC analysis of the reaction mixture and UV detection at 250 nm discriminated D- and L-enantiomers of aldoses. The reaction was applied to the determination of absolute configuration the sugar residues of an aroma precursor.     

Determination of paclitaxel in human and rat blood samples after administration of low dose paclitaxel by HPLC-UV detection

A simple and sensitive HPLC-UV method was developed for the determination of paclitaxel (TXL) in human and rat blood samples. 4-Hydroxybenzoic acid n-hexyl ester was used as an internal standard. TXL was extracted by a liquid-liquid extraction with tert-butylmethyl ether. The disturbing peaks in the case of serum sample were removed by pre-extraction with hexane. The separation of TXL was achieved within 25 min using an ODS column with 50% acetonitrile aqueous solution as a mobile phase at a flow rate of 1.0 mL/min. The eluent was monitored at 230 nm, and the resulted retention times of TXL and IS were 11.2 and 20.4 min. The detection limits of TXL for human plasma, serum and rat plasma samples at a signal-to-noise ratio of 3 were 10, 9.5 and 7.5 ng/mL, respectively. The proposed methods were applicable to the determination of TXL in human patients' plasma ranging from 15 to 27 ng/mL. Furthermore, monitoring of the time course of TXL after its single administration to rat could be demonstrated.     

Determining the angle of repose of sand under low-gravity conditions using discrete element method

This study is a comparative investigation of data, collected through experimental and numerical means, related to the flow of sand particles through a hopper under low-gravity conditions. During a parabolic airplane flight simulating low-gravity conditions, we determined effects of gravity on the angle of repose of sand pile particles by flowing dry sand from a hopper. The gravity effects on the angle of repose of the sand were negligible. Two-dimensional discrete element method (DEM) was used to simulate the angle of repose. Results were compared to observations made during the low-gravity experiments. Effects of varying parameters such as the friction coefficient and coefficient of rolling friction were determined by running various DEM simulations. Moreover, the effect of the elemental radius on the angle of repose was investigated using DEM. The angle of repose is influenced by certain changes in the friction coefficient and rolling friction values, but the elemental radius has only a negligible effect on the angle of repose within the range of variation. Results show that the DEM model used for this study might be applicable to determine terramechanical interactions under lunar surface gravity conditions, provided that parameters are adjusted and an extended period of simulation is achieved.     

Fe(z+) (z = 1-6) generation from ferrocene

Multiply charged iron atoms up to Fe(6+) with few carbon ions were produced from ferrocene under intense femtosecond laser fields. The production of Fe(4+) and Fe(5+) from ferrocene requires much less laser intensity than theoretically expected for iron atoms. The dissociation of ferrocene and the generation mechanism of multiply charged iron atoms are discussed.