Preparation and study of a capillary electrochromatographic column prepared by conjugating ß-CD COFs and gold-poly glycidyl methacrylate nanoparticles.

A new enantioselective open-tubular capillary electrochromatography (OT-CEC) was developed employing ß-cyclodextrin covalent organic frameworks (ß-CD COFs) conjugated gold-poly glycidyl methacrylate nanoparticles (Au-PGMA NPs) as a stationary phase. The resulting coating layer on the inner wall of the fabricated capillary column was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), energy dispersive spectroscopy (EDS), and electroosmotic flow (EOF) experiments. The performance of the fabricated capillary column was evaluated by CEC using enantiomers of seven model analytes, including two proton pump inhibitors (PPIs, omeprazole and tenatoprazole), three amino acids (AAs, tyrosine, phenylalanine, and tryptophan), and two fluoroquinolones (FQs, gatifloxacin and sparfloxacin). The influences of coating time, buffer concentration, buffer pH, and applied voltage on enantioseparation were investigated to obtain satisfactory enantioselectivity. In the optimum conditions, the enantiomers of seven analytes were fully resolved within 10 min with high resolutions of 3.03 to 5.25. The inter- to intra-day and column-to-column repeatabilities of the fabricated capillary column were lower than 4.26% RSD. Furthermore, molecular docking studies were performed based on the chiral fabricated column and as ligand isomers of analytes using Auto Dock Tools. The binding energies and interactions acquired from docking results of analytes supported the experimental data.

ß-Cyclodextrin covalent organic framework supported by polydopamine as stationary phases for electrochromatographic enantioseparation.

In this work, a new open-tubular capillary electrochromatography (OT-CEC) column was prepared using ß-cyclodextrin covalent organic framework (ß-CD COF) as a stationary phase. Polydopamine was used to assist fabrication of ß-CD COF on an inner wall of a fused-silica capillary. The coating layer on the capillary was characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Electroosmotic flow (EOF) was also studied to evaluate the variation of the inner wall of immobilized columns. Furthermore, the chiral separation effectiveness of the fabricated capillary column was evaluated by CEC using enantiomers of several related proton pump inhibitors as model analytes, including omeprazole, lansoprazole, pantoprazole and tenatoprazole. The effects of bonding time and concentration of ß-CD COF, the type, concentration and pH of buffer, applied voltage were investigated to obtain satisfactory enantioselectivity. In the optimum conditions, the enantiomers of four analytes were resolved within 15 min with resolutions of 1.63-2.62. The relative standard deviation values for migration times and resolutions of the analytes representing intraday and interday were less than 6.75% and 4.24%, respectively. The results reveal that ß-CD COF has great potential as chiral-stationary phases for enantioseparation in CEC.

Preparation of a polydopamine/ß-cyclodextrin coated open tubular capillary electrochromatography column and application for enantioseparation of five proton pump inhibitors.

An open tubular capillary electrochromatography column was prepared by immobilizing ß-cyclodextrin on the inner wall of pretreated capillary via noncovalent adsorption of polydopamine. The resulting coating layer on the capillary was characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. Electroosmotic flow was studied to evaluate the variation of the immobilized columns. The prepared columns showed good chiral separation performance toward five proton pump inhibitors including lansoprazole, pantoprazole, tenatoprazole, rabeprazole, and omeprazole. The influences of ß-cyclodextrin concentration, coating time, buffer pH, buffer concentration, and applied voltage on separation were investigated. In the optimum conditions, the enantiomers of five analytes were fully resolved within 15 min with high resolutions of 4.57 to 8.13. The method was extensively validated in terms of accuracy, precision, and linearity and proved to be robust. The relative standard deviation values for migration times and peak areas of the analytes representing intraday and interday were less than 1.9 and 3.6%, respectively. Further, the polydopamine/ß-cyclodextrin coated capillary column could be successively used over 100 runs without showing significant decrease in the separation efficiency.

A novel gastro-retentive osmotic pump capsule using asymmetric membrane technology: in vitro and in vivo evaluation.

PURPOSE: The purpose of this paper is to develop a novel gastro-retentive osmotic pump capsule using asymmetric membrane technology. METHODS: The physical characteristics of capsule walls and drug delivery behaviors of the system were compared through different coating solutions. The formulation with the glycerin and diethyl phthalate ratio of 5:4 appears to be the best. The thickness of asymmetric membranes was evaluated by withdrawing speed. The relation between the two can be fitted to a linear model. The floating abilities were investigated through filling polyethylene oxide of different molecular weight into the capsules. WSR N-80 (molecular weight 200000) is chosen for the longest floating time. Central composite design-response surface methodology was used to investigate the influence of factors on the responses. The in vivo pharmacokinetics were studied in beagle dogs. RESULTS AND CONCLUSIONS: A second-order polynomial equation was fitted to the data, and the actual response values are in good accordance with the predicted ones. The optimized formulation displays a complete drug delivery, zero-order release rate and 12 h floating time. The in vivo study results clearly indicate the controlled and sustained release of Famotidine from the system, and the relative bioavailability of this preparation is about 1.605 in comparison to that of the marketed preparation.

Preparation of sulfobutylether ß-cyclodextrin-silica hybrid monolithic column, and its application to capillary electrochromatography of chiral compounds.

Although various cyclodextrins (CDs) have been utilized to prepare organic polymer-based monolithic columns, there were few reports on fabrication of cyclodextrin functionalized hybrid monolithic columns. Herein, a sulfobutylether ß-cyclodextrin (SBE-ß-CD)-silica hybrid monolithic column was prepared by "one-step" method via the co-polymerization of hydrolyzed organosiloxane precursors and glycidyl methacrylate-sulfobutylether ß-cyclodextrin (GMA-SBE-ß-CD). The morphologies of prepared monolithic columns were observed by optical microscopy and scanning electron microscopy (SEM). The sulfobutylether ß-cyclodextrin was incorporated into the polymeric structure, which was demonstrated by energy dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR) spectrum and X-ray photoelectron spectroscopy (XPS). The resulting columns were used for chiral separations of twenty six racemic compounds, and satisfactory separation selectivity was obtained. Compared with other two kinds of neutral cyclodextrin (ß-CD and HP-ß-CD) based hybrid monoliths, sulfobutylether ß-cyclodextrin-silica hybrid monolith showed superior chiral resolution. These results demonstrated the sulfobutylether ß-cyclodextrin-silica hybrid monolithic column was promising in chiral compounds analysis.

Optimized preparation of vinpocetine proliposomes by a novel method and in vivo evaluation of its pharmacokinetics in New Zealand rabbits.

Free-flowing proliposomes which contained vinpocetine were prepared successfully to increase the oral bioavailability of vinpocetine. In this study the proliposomes were prepared by a novel method which was reported for the first time and the formulation was optimized using the centre composite design (CCD). The optimized formulation was Soybean phosphatidylcholine: 860 mg; cholesterol: 95 mg and sorbitol: 8000 mg. After the proliposomes were contacted with water, the suspension of vinpocetine liposomes formed automatically and the entrapment efficiency was approximately 86.3% with an average particle size of about 300 nm. The physicochemical properties of the proliposomes including SEM, TEM, XRD and FTIR were also detected. HPLC system was applied to study the concentration of vinpocetine in the plasma of the New Zealand rabbits after oral administration of vinpocetine proliposomes and vinpocetine suspension. The pharmacokinetic parameters were calculated by the software program DAS2.0. The concentration-time curves of vinpocetine suspension and vinpocetine proliposomes were much more different. There were two absorption peaks on the concentration-time curves of the vinpocetine proliposomes. The pharmacokinetic parameters of vinpocetine and vinpocetine proliposomes in New Zealand rabbits were T(max) 1 h and 3 h (there was also an absorption peak at 1 h); C(max) 163.82+/-12.28 ng/ml and 166.43+/-21.04 ng/ml; AUC(0-infinity) 1479.70+/-68.51 ng/ml h and 420.70+/-35.86 ng/ml h, respectively. The bioavailability of vinpocetine in proliposomes was more than 3.5 times higher than the vinpocetine suspension. The optimized vinpocetine proliposomes did improve the oral bioavailability of vinpocetine in New Zealand rabbits and offer a new approach to enhance the gastrointestinal absorption of poorly water soluble drugs.