Ruimiao Chang

Development of molecular imprinted column-on line-two dimensional liquid chromatography for selective determination of clenbuterol residues in biological samples

A novel method coupling molecular imprinted monolithic column with two-dimensional liquid chromatography was developed and validated for the analysis of clenbuterol in pork liver and swine urine samples. The polymers were characterized by using Fourier transform infrared spectroscopy, nitrogen adsorption desorption analyses, frontal analysis and the adsorption of selectivity. The results indicated that the imprinted columns were well prepared and possessed high selectivity adsorption capacity. Subsequently, the MIMC-2D-LC (molecular imprinted monolithic column-two dimensional liquid chromatography) method was developed for the selective analysis of clenbuterol in practical samples. The accuracy ranged from 94.3% to 99.7% and from 93.7% to 99.6% for liver and urine, respectively. The relative standard deviation (RSD) of repeatability was lower than 8.6% for both analyses. The limit of detections was 16ng·mL(-1) for liver and 25ng·mL(-1) for urine, respectively. Compared with the reported methods, the disturbance of endogenous impurity could be avoided by the 2D-LC method.

β-Cyclodextrin anchoring onto pericarpium granati-derived magnetic mesoporous carbon for selective capture of lopid in human serum and pharmaceutical wastewater samples.

Functionalized magnetic carbonaceous nanomaterials, which are important materials with many practical and research applications in biomedical, pharmaceutical and biological fields, have recently attracted much attention. In this study, a magnetic mesoporous carbon coated with β-cyclodextrin (MMC@β-CD) was synthesized for the first time from natural pericarpium granati (PG). The as-obtained MMC@β-CD has high surface areas (203 m(2)g(-1)), large pore volumes (0.16 cm(3)g(-1)), relatively broad mesoporous sizes (6.8 nm) and a high saturation magnetization of 26.2 emu g(-1), which is sufficient for magnetic separation by an external magnetic field. The MMC@β-CD was used as an innovative adsorbent for magnetic solid-phase extraction of lopid via host-guest interaction prior to spectrofluorometric analysis. The proposed method was successfully applied to analyze lopid in human serum and pharmaceutical wastewater samples with recoveries in the range of 85.0-103.5% for the spiked samples. Overall, this work not only provides an inexpensive and eco-friendly method to fabricate MMC@β-CD (or MMC) from PG, but also develops a highly selective approach for capture of lopid in biological samples and environmental substances.

A porous hybrid imprinted membrane for selectively anchoring target proteins from a complex matrix

A novel porous hybrid imprinted membrane (CP/CNT/DA-MIM) was prepared that could selectively anchor and separate target proteins from a complex matrix. CP/CNT/DA-MIM exhibits many of the advantages of molecularly imprinted polymers and membranes, including the high selectivity of MIPs, the lower energy consumption and the ability to continuously separate mixtures via membrane separation. The surface morphologies and physical/chemical properties of the different membranes were investigated using FTIR, XRD, DSC, XPS and SEM. The results showed that the different molecules contained within CP/CNT/DA-MIM were homogeneous; two different sizes of imprinted cavities were observed in CP/CNT/DA-MIM, which facilitate the selective anchoring property. The adsorption capacities, swelling behaviors and mechanical properties of the different constituent membranes were also compared. The results show that the adhesion and nonspecific adsorption properties of the membrane were manifestly reduced through the addition of PVP. The binding capacity and adsorption selectivity of the membrane were apparently improved because of the presence of dopamine. MWCNTs obviously improved the mechanical strength of the membranes. CP/CNT/DA-MIM was successfully applied to separate bovine serum albumin from bovine blood. CP/CNT/DA-MIM is an economical, hydrophilic and ecofriendly membrane and is a promising separation material for the large-scale continuous selective separation of target proteins from complex matrices in commercial applications.

Preparation and characterization of surface molecularly imprinted films coated on multiwall carbon nanotubes for recognition and separation of lysozyme with high binding capacity and selectivity

In this work, a series of facile and efficient molecularly imprinted polymers (MIPs) for the selective recognition and separation of lysozyme were synthesized by combining self-polymerization and nanosized matrix. The imprinted materials containing recognition sites for the lysozyme were formed via using both carboxyl-functionalized multi-walled carbon nanotubes (MWCNTs-COOH) as a support and dopamine (DA) with excellent biocompatibility as a functional monomer. The obtained polymers were characterized and evaluated by using field-emission scanning electron microscopy (FESEM), field-emission transmission electron microscopy (FETEM), nitrogen physisorption experiments, Fourier transform infrared (FT-IR) spectroscopy and thermogravimetric analysis (TGA). The optimum reaction conditions and adsorption performance of the resultant nanomaterials were also investigated. MIPs synthesized by this method exhibited excellent imprinting factor (4.1) and high binding capacity (418 mg g−1) for lysozyme. After six adsorption–desorption cycles, the adsorption capacity of the MIPs was only reduced by 7.4%. In addition, the prepared MIPs were used to separate and condense lysozyme from chicken egg white successfully, which showed potential values in industrial protein purification, basic biomedical research and clinical diagnostics.

A new polymorphic form and polymorphic transformation of loratadine

In this work, a new form of loratadine (Form B) was prepared from a 20% methanol and 80% water mixture and characterized by polarizing microscopy (POM), scanning electron microscopy (SEM), powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC). The dissolution, solubility and interfacial energy of Form B in water were measured and compared with those of amorphous and Form A loratadine. In addition, the solid-state transformations of loratadine solid forms were investigated by hot-stage microscopy (HSM) and DSC while the non-isothermal crystallization of amorphous loratadine was studied by DSC. It was found that Form B has a unique acicular structure and PXRD pattern, which are different from Form A. Moreover, Form B has a higher equilibrium solubility compared with Form A. The results of the solid-state transformation investigation (DSC) shows that the amorphous form was changed to the new polymorph B at 106.7 °C and Form B converted exothermally to Form A at 93.9 °C during heating. In the non-isothermal crystallization of amorphous loratadine, the crystallization rate constant (Zt) increased with the increasing heating rate and the Avrami exponent (n) was found to be about 3. Hopefully, Form B will be considered to be a promising approach to improve the loratadine solubility/dissolution rate.

Molecularly Imprinted Solid Phase Extraction using Bismethacryloyl-β-cyclodextrin and Methacrylic Acid as Double Functional Monomers for Selective Analysis of Glycyrrhizic Acid in Aqueous Media.

Abstract In this work, a new molecularly imprinted solid phase extraction protocol was developed for the selective extraction and purification of glycyrrhizic acid from liquorice roots in aqueous media. The molecularly imprinted polymers (MIPs) for glycyrrhizic acid were prepared by using bismethacryloyl-β-cyclodextrin and methacrylic acid as double functional monomers and characterized by Fourier transform infrared spectroscopy, scanning electron microscope, thermo gravimetric analysis, nitrogen adsorption and elemental analysis. In aqueous media, the adsorption properties of MIPs including adsorption kinetics, adsorption isotherms and selectivity adsorption were investigated. The characterization of imprinted polymers indicated that the prepared MIPs had good stability and many cavity structures. The results of adsorption experiments illustrated the MIPs had high adsorption capacity of glycyrrhizic acid (69.3 mg g−1) with the imprinting factor 3.77, and it took ~5 min to get adsorption equilibrium. The MIPs could be used as an solid phase extraction sorbent absorbent for enrichment and purification of glycyrrhizic acid from the crude extraction of licorice roots, and the results showed promising practical value.

Crystallization and relaxation dynamics of amorphous loratadine under different quench-cooling temperatures

In this paper, four amorphous samples of loratadine were prepared by quench-cooling the melted drug at different temperatures. With these samples, the crystallization tendencies were tested by powder X-ray diffraction (PXRD), and non-isothermal cold crystallization kinetics was investigated by using differential scanning calorimetry (DSC) and the molecular dynamics both in super-cooled liquid and in glassy states was analyzed by using broadband dielectric spectroscopy (BDS) at a temperature range from 213 to 393 K. From the PXRD results, it was established that the four amorphous loratadine samples were apt to crystallize at a temperature below the glass transition temperature. From the DSC results, it was found that the non-isothermal crystallization mechanism of these four loratadine forms was similar. However, the fast crystallization tendency (low physical stability) was also observed for the amorphous loratadine which was obtained at a low quench-cooling temperature. The tendency was analyzed based on the BDS results which demonstrated that rapid molecular mobility could generate a low physical stability and was closely related to Johari–Goldstein relaxation. These results suggested that loratadine had a weak frustration against crystallization and its physical stability was affected by the quench-cooling temperature. This study laid a foundation for choosing the right technique to prepare the amorphous form of loratadine and improving its physical stability.

Selective determination of penicillin G from tap water and milk samples using surface molecularly imprinted polymers as solid-phase extraction sorbent

Abstract In this study, a selective sample preparation method coupling surface molecularly imprinting polymers (SMIPs) with solid-phase extraction (SPE) was developed for the determination of penicillin G from tap water and milk samples. SMIPs for penicillin G were synthesized by using silica gel as supporting matrix, methacrylic acid (MAA) as the functional monomer, ethylene glycol dimethacrylate (EDMA) as the cross-linker, methanolacetonitrile (1:1,v/v) as the solvents and 2,2′-azo-bisisobutyronitrile (AIBN) as the initiator. Characterization and adsorption experiments revealed that SMIPs exhibited large adsorption capacity, high recognition ability and high rate of mass transfer. Application of SMIPs in SPE followed by HPLC was done to selectively determine penicillin G from tap water and milk samples. Under the optimal conditions, the proposed method demonstrated high linearity with the concentration of penicillin G ranging from 0.12 to 200 μg mL-1. The limits of detection (LOD) in tap water and milk were 0.05, 0.03μg mL-1, respectively. The limits of quantification (LOQ) in tap water and milk were 0.25, 0.12 μg mL-1, respectively. The recoveries of penicillin G at three spiked levels were ranged from 78.9 to 85.5 % with intra-day and inter-day relative standard deviation values below 4.8 %.

Facile preparation of polydopamine-coated imprinted polymers on the surface of SiO2 for estrone capture in milk samples.

Estrone molecularly imprinted polymers were synthesized through the self-polymerization of dopamine on the surface of silica gels, which had the characteristics of mild polymerization conditions, simple reaction procedure and good specific recognition ability for estrone. The estrone molecularly imprinted polymers were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, elemental analysis and nitrogen adsorption-desorption tests. The characterization confirmed that the imprinted polymers were successfully grafted on the surface of silica gels. Through investigating the adsorption performance, the prepared estrone molecularly imprinted polymers exhibited high adsorption capacity, fast mass transfer, as well as excellent selectivity toward estrone. The estrone molecularly imprinted polymers as the solid-phase extraction adsorbent coupled with high-performance liquid chromatography was developed to determine estrone from the milk samples. The developed estrone molecularly imprinted polymer solid-phase extraction with high-performance liquid chromatography method exhibited satisfactory specificity, precision, accuracy and good linearity relationship in the range of 0.2-20 μg/mL. The developed method is simple, fast, effective and high specificity method and it provides a new method to detect the residues of estrone in animal foods.

An HPLC method for the determination of a novel anti‐hypertension agent 6,7‐dimethoxy‐3‐(4‐(4‐fluorobenzyloxy)‐3‐methoxyphenylmethyl)quinazolin‐4(3H)‐one in rat plasma: application to pharmacokinetic study

6,7-dimethoxy-3-(4-(4-fluorobenzyloxy)-3-methoxyphenylmethyl) quinazolin-4(3H)-one (DFMQ-19), a novel analogue of 3-benzylquinazolin-4(3H)-ones, may be considered as a drug candidate for the treatment of hypertension. The aim of this study was to develop and validate a reverse-phase high-performance liquid chromatography to determine the DFMQ-19 in plasma and demonstrate its application in pharmacokinetic study. Separation of DFMQ-19 and I.S (structural analog of DFMQ-19) was performed using Shim-Pack VP-ODS column and a mixture of acetonitrile and water as mobile phase. The HPLC method was validated according to the ICH guidelines. The limit of detection and lower limit of quantitation were 0.05 µg/ml and 0.1 µg/ml respectively. The recovery rate of DFMQ-19 from blood samples was >81% of the spiked amount. The RSD of the intra- and inter-day precisions was within 7.5%, and RE of accuracy was between -14.4% and 4.5%. This method was successfully applied to the pharmacokinetic study after administration of DFMQ-19. The pharmacokinetic parameters, such as half-life (t1/2 ), mean residence time (MRT), maximum concentration (Cmax ) were determined. Based on these pharmacokinetic parameters, the oral bioavailability of DFMQ-19 was calculated to be 13.42% in rat. This article is protected by copyright. All rights reserved. HIGHLIGHTS HPLC method was validated to quantify DFMQ-19 in rat plasma I.S is one of the structural analogs of the analyte The HPLC method was validated according to the ICH guidelines The oral bioavailability of DFMQ-19 was 13.42% in rat.