Free-electron-laser coherent diffraction images of individual drug-carrying liposome particles in solution.

Using the excellent performances of a SACLA (RIKEN/HARIMA, Japan) X-ray free electron laser (X-FEL), coherent diffraction imaging (CDI) was used to detect individual liposome particles in water, with or without inserted doxorubicin nanorods. This was possible because of the electron density differences between the carrier, the liposome, and the drug. The result is important since liposome nanocarriers at present dominate drug delivery systems. In spite of the low cross-section of the original ingredients, the diffracted intensity of drug-free liposomes was sufficient for spatial reconstruction yielding quantitative structural information. For particles containing doxorubicin, the structural parameters of the nanorods could be extracted from CDI. Furthermore, the measurement of the electron density of the solution enclosed in each liposome provides direct evidence of the incorporation of ammonium sulphate into the nanorods. Overall, ours is an important test for extending the X-FEL analysis of individual nanoparticles to low cross-sectional systems in solution, and also for its potential use to optimize the manufacturing of drug nanocarriers.

A Model Prediction for Chenodeoxycholate Aggregate Formation.

A relationship between the chenodeoxycholate (CDC) monomer concentration and the total concentration of CDC was established using a kinetic dialysis technique. Meanwhile, the sizes of the formed simple CDC micelles were measured by a quasielastic light-scattering (QLS) technique to be nearly constant. The QLS results led to a suggestion for equilibrium models of CDC aggregate formation. According to the established relationship and the suggested models, the best curve-fitting model was selected by a least-squares technique. Furthermore, the model parameters were quantified. Based on the quantified parameters, at a minimum detectable concentration of simple CDC micelles to be ∼0.2 mM, an appropriate model corresponding concentration of CDC monomers was estimated to be ∼3.08 mM. This value is consistent with a minimum monomer CDC concentration of ∼3.13 mM for simple CDC micelle formation estimated according to the present QLS detection and the model prediction. The consistency confirms the model prediction that at a low CDC monomer concentration (<3 mM), the concentration of stable CDC dimers is much higher than that of simple CDC micelles but the contribution of simple CDC micelles to the total CDC concentration cannot be negligible.

Overcoming Multidrug Resistance through the Synergistic Effects of Hierarchical pH-Sensitive, ROS-Generating Nanoreactors.

Recently, multidrug resistance (MDR) has become a major clinical chemotherapeutic burden that robustly diminishes the intracellular drug levels through various mechanisms. To overcome the doxorubicin (Dox) resistance in tumor cells, we designed a hierarchical nanohybrid system possessing copper-substituted mesoporous silica nanoparticles (Cu-MSNs). Further, Dox was conjugated to copper metal in the Cu-MSNs framework through a pH-sensitive coordination link, which is acutely sensitive to the tumor acidic environment (pH 5.0-6.0). In the end, the nanocarrier was coated with D-α-Tocopherol polyethylene glycol 1000 succinate (TPGS), a P-gp inhibitor-entrenched compact liposome net for obstructing the drug efflux pump. Copper ions in the framework synergize the antitumor activity of Dox by enhancing the intracellular reactive oxygen species (ROS) levels through a Fenton-like reaction-mediated conversion of hydrogen peroxide. Furthermore, intracellularly generated ROS triggered the apoptosis by reducing the cellular as well as mitochondrial membrane integrity in MDR cells, which was confirmed by the mitochondrial membrane potential (MMP) measurement. The advancement of the design and critical improvement of cytotoxic properties through free radical attack demonstrate that the proposed hierarchical design can devastate the MDR for efficient cancer treatment.

Electrochemical determination of L-phenylalanine at polyaniline modified carbon electrode based on ß-cyclodextrin incorporated carbon nanotube composite material and imprinted sol-gel film.

A sensitive and selective electrochemical sensor based on a polyaniline modified carbon electrode for the determination of L-phenylalanine has been proposed by utilizing ß-cyclodextrin (ß-CD) incorporated multi-walled carbon nanotube (MWNT) and imprinted sol-gel film. The electrochemical behavior of the sensor towards L-phenylalanine was investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV), and amperometric i-t curve. The surface morphologies of layer-by-layer assembly electrodes were displayed by scanning electron microscope (SEM). The response mechanism of the imprinted sensor for L-phenylalanine was based on the inclusion interaction of ß-CD and molecular recognition capacity of the imprinted film for L-phenylalanine. A linear calibration plot was obtained covering the concentration range from 5.0 × 10(-7) to 1.0 × 10(-4) mol L(-1) with a detection limit of 1.0 × 10(-9) mol L(-1). With excellent sensitivity, selectivity, stability, reproducibility and recovery, the electrochemical imprinted sensor was used to detect L-phenylalanine in blood plasma samples successfully.

Quantitative determination of omapatrilat and its metabolites in human plasma by HPLC coupled with tandem mass spectrometry.

AIM: To develop a sensitive and specific analytical method for the quantitative determination of omapatrilat (BMS-186716) and its metabolites (BMS-196087, 225308, 198433, and 253653) in human plasma. METHODS: Methyl acrylate (MA) was selected to react with BMS-186716, 196087, and 253653 to protect the free sulfhydryl groups. High pressure liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was used to detect the analytes. RESULTS: The method was validated over the concentration range of 0.2-250 microg/L for BMS-186716, 0.5-250 microg/L for BMS-196087, 1-250 microg/L for BMS-225308, 2-250 microg/L for BMS-198433, and 10-2500 microg/L for BMS-253653. The limit of quantitation was in turn 0.2, 0.5, 1, 2, and 10 microg/L, respectively. The extraction recovery was on average 60.5 %, 88.6 %, 76.3 %, 71.2 %, and 26.6 %, respectively. Inter- and intra-day precision of quality control samples (QC) was all within 15 % and accuracy was within 85 %--115 %. The analytes in human plasma were found to be stable after three cycles of freeze-thaw and for at least 6 h at room temperature (25 oC). No significant change was found in reconstituted reagent after 24 h at room temperature and results of long-term stability showed all the analytes in human plasma were stable for at least 3 months at -30 oC freezing condition. CONCLUSION: This method is rapid, sensitive and specific for the pharmacokinetics study of omapatrilat and its metabolites.