Delivery of curcumin using a zein-xanthan gum nanocomplex: Fabrication, characterization, and in vitro release properties.

This study aimed to use xanthan gum as a stabilizer to improve the stability of zein nanoparticles. Zein-xanthan gum composite nanoparticles were prepared via anti-solvent precipitation at pH 4.0. The particle size, zeta potential, and stability of the system were related to the amount of xanthan gum added. When 20 mg of xanthan gum was added, spherical nanoparticles with a small particle size (179 ± 2.1 nm) and sufficient negative zeta potential (-42 ± 1.6 mV) were obtained. The zeta potential and Fourier transform infrared spectroscopy results indicated that electrostatic attraction was the main driving force, followed by hydrogen bonding and hydrophobic interactions. Composite nanoparticles were coated by xanthan gum and remained stable over a wide pH range and at high temperatures and salt concentrations; they did not precipitate or aggregate after 30 days of storage. Moreover, the addition of xanthan gum considerably improved the encapsulation efficiency and loading capacity of nanoparticles containing high curcumin amounts, which facilitated slow and sustained release of curcumin in simulated intestinal fluid. Therefore, zein-xanthan gum nanoparticles can be used for the delivery of biologically active compounds in food and pharmaceutical preparations.

Fabrication of Carboxymethylcellulose/Metal-Organic Framework Beads for Removal of Pb(II) from Aqueous Solution.

The ability to remove toxic heavy metals, such as Pb(II), from the environment is an important objective from both human-health and ecological perspectives. Herein, we describe the fabrication of a novel carboxymethylcellulose-coated metal organic material (MOF-5⁻CMC) adsorbent that removed lead ions from aqueous solutions. The adsorption material was characterized by Fourier-transform infrared spectroscopy, X-ray diffractometry, scanning electron microscopy, and X-ray photoelectron spectroscopy. We studied the functions of the contact time, pH, the original concentration of the Pb(II) solution, and adsorption temperature on adsorption capacity. MOF-5⁻CMC beads exhibit good adsorption performance; the maximum adsorption capacity obtained from the Langmuir isotherm-model is 322.58 mg/g, and the adsorption equilibrium was reached in 120 min at a concentration of 300 mg/L. The adsorption kinetics is well described by pseudo-second-order kinetics, and the adsorption equilibrium data are well fitted to the Langmuir isotherm model (R² = 0.988). Thermodynamics experiments indicate that the adsorption process is both spontaneous and endothermic. In addition, the adsorbent is reusable. We conclude that MOF-5⁻CMC is a good adsorbent that can be used to remove Pb(II) from aqueous solutions.

Facile fabrication of core-shell/bead-like ethylenediamine-functionalized Al-pillared montmorillonite/calcium alginate for As(V) ion adsorption.

In this study, a MT(Al)/calcium alginate [MT(Al)@CA] microsphere structure was prepared using sodium alginate (SA) and MT(Al). In order to achieve [MT(Al)@CA] microspheres with a high stability and chemical resistance, glutaraldehyde was used as the crosslinking agent to graft the microspheres and ethylenediamine (ED) into a new type of ED-functionalized MT(Al)@CA microsphere structure similar to a core-shell-type structure [MT(Al)@CA-ED]. This core-shell/bead-like structure was characterized and analyzed by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The adsorption performance of the core-shell/bead-like structure for As(V) in solution was studied. The effects of the initial As(V) concentration, reaction time, pH, and different reaction temperatures on the reaction process were studied. The results indicate that at a pH of 4, the removal rate of As(V) by the core-shell/bead-like MT(Al)@CA-ED could reach 94.85% after 150 min. The adsorption process is highly consistent with the Langmuir isotherm model (R2 = 0.9983) and pseudo-second-order kinetic model (R2 = 0.9973). The maximum adsorption capacity could reach 61.94 mg/g. Regeneration experiments showed that the adsorption efficiency of As(V) after six cycles was >80%.

Adsorption of diclofenac sodium on bilayer amino-functionalized cellulose nanocrystals/chitosan composite.

Residual diclofenac sodium (DS) in the environment is harmful to human health. A promising method for DS removal is the use of adsorbents functionalized with amino groups that can form an ionic bond with the carboxyl group of DS at a suitable pH. In this work, a novel composite adsorbent composed of cellulose nanocrystals (CNC) and chitosan (CS) has been synthesized and functionalized by ethylenediamine (ED) in both layers. Characterization methods, including scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, Fourier-transform infrared spectrometry, and X-ray photoelectron spectroscopy, were used to confirm the morphology and synthetic mechanism of the double- amino-functionalized adsorbent. Based on the optimization of adsorption conditions and modeling of the adsorption mechanism, the DS adsorption process on CNC-ED@CS-ED involves chemical adsorption, and the maximum adsorption capacity obtained from the Langmuir model is 444.44 mg/g. CNC-ED@CS-ED exhibits good adsorption capacity and high sustainability; thus, it is a promising composite material for the removal of DS from wastewater.

Efficient adsorption of diclofenac sodium from aqueous solutions using magnetic amine-functionalized chitosan.

In this study, we prepared a magnetic composite based on amine-functionalized chitosan (aminochitosan; AmCS) and Fe3O4 to remove diclofenac sodium (DS) from water. The fabricated AmCS@Fe3O4 composite was characterized using Fourier-transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, vibrating sample magnetometry, X-ray diffraction, and thermogravimetric analysis. Furthermore, we investigated the influence of pH, initial DS concentration, and adsorbent dosage on the adsorption of DS. Through thermodynamic analysis, we found that the data corresponded with the Langmuir adsorption isotherm model. The maximum adsorption capacity reached 469.48 mg g-1, and the adsorption process followed the pseudo-second-order kinetic model. Finally, the AmCS@Fe3O4 composite retained good adsorption characteristics after four consecutive cycles, with removal efficiency exceeding 70%. Therefore, the developed adsorbent could be used for efficient adsorptive removal of trace drugs and personal care products from water bodies.

Highly efficient adsorption of Pb(II) from aqueous solution using amino-functionalized SBA-15/calcium alginate microspheres as adsorbent.

In this work, amino-functionalized Santa Barbara Amorphous-15/calcium alginate (ASBA-15@CA) microspheres were fabricated and characterized by FTIR, SEM, XRD, TGA, and XPS analyses. The Pb(II) adsorption properties of the ASBA-15@CA microspheres were studied in terms of the effects of the adsorption time, adsorbent dose, solution pH, temperature, and initial concentration of Pb(II) on the adsorption capacity. At pH 6 and 298 K, the adsorption reached equilibrium after 100 min and the sample exhibited a good adsorption effect, affording a maximum adsorption capacity of 1029.58 mg/g and a removal rate as high as 98.99%. The adsorption process conformed to the Langmuir model (R2 = 0.9937) and followed the pseudo-second-order kinetics model (R2 = 0.9995). Regeneration experiments showed that the removal rate of the sample reached 75% even after 6 cycles. Overall, this study provides new insights into the development of novel, highly efficient, and repeatable degradation materials for the removal of Pb(II).

Facile Preparation of Metal-Organic Framework (MIL-125)/Chitosan Beads for Adsorption of Pb(II) from Aqueous Solutions.

In this study, novel composite titanium-based metal-organic framework (MOF) beads were synthesized from titanium based metal organic framework MIL-125 and chitosan (CS) and used to remove Pb(II) from wastewater. The MIL-125-CS beads were prepared by combining the titanium-based MIL-125 MOF and chitosan using a template-free solvothermal approach under ambient conditions. The surface and elemental properties of these beads were analyzed using scanning electron microscopy, Fourier transform infrared and X-ray photoelectron spectroscopies, as well as thermal gravimetric analysis. Moreover, a series of experiments designed to determine the influences of factors such as initial Pb(II) concentration, pH, reaction time and adsorption temperature was conducted. Notably, it was found that the adsorption of Pb(II) onto the MIL-125-CS beads reached equilibrium in 180 min to a level of 407.50 mg/g at ambient temperature. In addition, kinetic and equilibrium experiments provided data that were fit to the Langmuir isotherm model and pseudo-second-order kinetics. Furthermore, reusability tests showed that MIL-125-CS retained 85% of its Pb(II)-removal capacity after five reuse cycles. All in all, we believe that the developed MIL-125-CS beads are a promising adsorbent material for the remediation of environmental water polluted by heavy metal ions.

Fabrication of Composite Beads Based on Calcium Alginate and Tetraethylenepentamine-Functionalized MIL-101 for Adsorption of Pb(II) from Aqueous Solutions.

In this work, a tetraethylenepentamine (TEPA)-grafted metal-organic framework material (MIL-101) was synthesized. The introduction of TEPA increased the abundance of functional groups on the MIL-101. As a powdery adsorbent, MIL-101-TEPA can be difficult to separate. In order to solve this problem, we combined MIL-101-TEPA with sodium alginate (SA) and injected the mixture into a CaCl2 solution to solidify the powder into beads with a particle size of 3 mm. The easily recovered adsorbent was applied to the adsorption of Pb(II) from water. The structure and characterization of the adsorbent were investigated through scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FTIR), X-Ray diffraction (XRD), thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS). We also optimized the adsorption conditions. The results of the study showed that the adsorption process was chemisorptive and endothermic in nature. The maximum adsorption capacity of the composite beads was 558.6 mg/g. Meanwhile MIL-101-TEPA@CA showed good repeatable utilization.

Efficient Adsorption of Pb(II) from Aqueous Solutions by Metal Organic Framework (Zn-BDC) Coated Magnetic Montmorillonite.

Composite adsorption materials combine the advantages of various adsorptive materials and compensate for the defects of single adsorbents. Magnetic montmorillonite (MMMT) shows good adsorption properties for Pb(II). In order to further improve the adsorption properties of MMMT, in this work, Zn-BDC, a kind of metal⁻organic framework (MOF), was modified onto the surface of MMMT by in situ polymerization. The composite material MMMT@Zn-BDC was characterized by Zetasizer, SEM, TEM, FTIR, XRD, VSM, and XPS. The influence of adsorption conditions on the adsorption capacity of MMMT@Zn-BDC for Pb(II) was examined, including the adsorbent dosage, pH of Pb(II) solution, initial concentration of Pb(II), and the temperature and adsorption time. Also, the adsorption mechanism was studied. The results of this study show that MMMT@Zn-BDC adsorbs Pb(II) via chemisorption. In addition, MMMT@Zn-BDC exhibits good potential for adsorbing Pb(II), including its high adsorption capacity (724.64 mg/g) and good recyclability.

Enantioseparation and enantioselective behavior of trichlorfon enantiomers in sediments.

Trichlorfon (TF), an organophosphorus insecticide, has been widely used in seawater aquaculture; it is easily degraded to the highly toxic insecticide, dichlorvos (DDVP). In this study, the enantioseparation of TF enantiomers, as well as their degradation behavior and product (DDVP) formation in mariculture pond sediments, was investigated. The results show that both TF enantiomers degrade into DDVP, which is the main degradation product. Furthermore, S-(+)-TF is preferentially degraded under natural conditions, suggesting that TF enantiomers degrade enantioselectively. Nevertheless, the degradation behavior of TF enantiomers is not enantiospecific under sterile conditions. The formation of DDVP and the enantiospecific degradation of TF enantiomers are attributed to the activities of microbes present in the sediments.

Surface-Imprinted Magnetic Carboxylated Cellulose Nanocrystals for the Highly Selective Extraction of Six Fluoroquinolones from Egg Samples.

We herein describe a novel adsorbent based on molecularly imprinted polymers (MIPs) on the surface of magnetic carboxylated cellulose nanocrystals (Fe3O4@CCNs@MIPs) for the separation and purification of six fluoroquinolones (FQs) from egg samples. The obtained Fe3O4@CCNs@MIPs not only exhibited a large surface area and specific recognition toward FQs, but also were easily gathered and separated from the egg samples using an external magnetic field. The morphologies and surface groups of the Fe3O4@CCNs@MIPs were assessed by X-ray photoelectron spectroscopy, transmission electron microscopy, vibrating sample magnetometry, X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, and Brunauer-Emmett-Teller surface area analysis. The Fe3O4@CCNs@MIPs exhibited high selectivity toward six structurally similar FQs. An enrichment approach was established for the measurement of six FQs from egg samples using Fe3O4@CCNs@MIPs coupled to high-performance liquid chromatography. The recovery of spiked FQs ranged from 75.2-104.9% and limit of detection was in the range of 3.6-18.4 ng g-1 for the six FQs. Therefore, the proposed method is a promising technique for the enrichment, separation, and determination of FQs from biomatrices.

Analysis of flumequine enantiomers in rat plasma by UFLC-ESI-MS/MS.

In this study the analysis and confirmation of flumequine enantiomers in rat plasma by ultra-fast liquid chromatography coupled with electron spray ionization mass spectrometry (using propranolol as an internal standard [IS]) was developed and validated. Plasma samples were prepared by liquid-liquid extraction using methyl tert-butyl ether as the extraction solvent. Direct resolution of the R- and S-isomers was performed on a CHIRALCEL OJ-RH column (4.6 × 150 mm, 5 µm) using acetonitrile / 0.1% formic acid / 1 mM ammonium acetate as the mobile phase. Detection was operated by electron spray ionization in the selected ion monitoring and positive ion mode. The target ions at m/z 262.1 and m/z 260.1 were selected for the quantification of the enantiomers and IS, respectively. The linear range was 0.5-500 ng/mL. The precisions (coefficient of variation, CV%) and recoveries were 1.43-8.68 and 94.24-106.76%, respectively. The lowest quantitation limit for both enantiomers is 0.5 ng/mL, which is sensitive enough to be applied to sample analysis in other related studies.

Validation of a Chiral Liquid Chromatographic Method for the Degradation Behavior of Flumequine Enantiomers in Mariculture Pond Water.

In this work, flumequine (FLU) enantiomers were separated using a Chiralpak OD-H column, with n-hexane-ethanol (20:80, v/v) as the mobile phase at a flow rate of 0.6 mL/min. Solid phase extraction (SPE) was used for cleanup and enrichment. The limit of detection, limit of quantitation, linearity, precision, and intra/interday variation of the chiral high-performance liquid chromatography (HPLC) method were determined. The developed method was then applied to investigate the degradation behavior of FLU enantiomers in mariculture pond water samples. The results showed that the degradation of FLU enantiomers under natural, sterile, or dark conditions was not enantioselective. Chirality 28:649-655, 2016. © 2016 Wiley Periodicals, Inc.

Synthesis and Characterization of Magnetic Molecularly Imprinted Polymer for the Enrichment of Ofloxacin Enantiomers in Fish Samples.

A new method for the isolation and enrichment of ofloxacin enantiomers from fish samples was developed using magnetic molecularly imprinted polymers (MMIPs). These polymers can be easily collected and rapidly separated using an external magnetic field, and also exhibit a high specific recognition for ofloxacin enantiomers. The preparation of amino-functionalized MMIPs was carried out via suspension polymerization and a ring-opening reaction using rac-ofloxacin as a template, ethylenediamine as an active group, glycidyl methacrylate and methyl methacrylate as functional monomers, divinylbenzene as a cross-linker, and Fe3O4 nanoparticles as magnetic cores. The characteristics of the MMIPs were assessed using transmission electron microscopy (TEM), X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and vibrating sample magnetometer (VSM) measurements. Furthermore, the adsorption properties were determined using Langmuir and Freundlich isotherm models. The conditions for use of these MMIPs as magnetic solid-phase extraction (MSPE) sorbents, including pH, adsorption time, desorption time, and eluent, were investigated in detail. An extraction method using MMIPs coupled with high performance liquid chromatography (HPLC) was developed for the determination of ofloxacin enantiomers in fish samples. The limits of quantitation (LOQ) for the developed method were 0.059 and 0.067 µg∙mL(-1) for levofloxacin and dextrofloxacin, respectively. The recovery of ofloxacin enantiomers ranged from 79.2% ± 5.6% to 84.4% ± 4.6% and ofloxacin enantiomers had good linear relationships within the concentration range of 0.25-5.0 µg∙mL(-1) (R² > 0.999). The obtained results demonstrate that MSPE-HPLC is a promising approach for preconcentration, purification, and simultaneous separation of ofloxacin enantiomers in biomatrix samples.

Pharmacokinetic study of ofloxacin enantiomers in Pagrosomus major by chiral HPLC.

(S)-(-)-Ofloxacin and (R)-(+)-ofloxacin concentrations in the plasma of Pagrosomus major after drug treatment were detected by chiral high-performance liquid chromatography, and various pharmacokinetic parameters were calculated from these data. The elimination half-life of (S)-(-)-ofloxacin was significantly shorter than that of the (R)-(+) enantiomer. (S)-(-)-Ofloxacin also had a significantly lower maximum plasma concentration, area under the concentration-time curve from zero to infinity, and mean residence time than (R)-(+)-ofloxacin. However, the apparent volume of distribution and total body clearance of (S)-(-)-ofloxacin were greater than those of (R)-(+)-ofloxacin. The ratio of the (S)-(-)- to (R)-(+)-ofloxacin plasma concentration was always <1.0. Together, these data suggest that (S)-(-)-ofloxacin was preferentially excreted and (R)-(+)-ofloxacin was preferentially absorbed. Although the difference in pharmacokinetic parameters was small, the metabolic behavior of the ofloxacin enantiomers in P. major was enantioselective.

Validation a solid-phase extraction-HPLC method for determining the migration behaviour of five aromatic amines from packaging bags into seafood simulants.

The simultaneous determination of five aromatic amines and their potential migration from packaging bags into seafood simulants were investigated. A validated HPLC method was developed for the separation and qualification of five aromatic amines in seafood simulants. By combining solid-phase extraction (SPE), these amines were efficiently separated on a Halo C18 column (150 × 4.6 mm i.d., 2.7 µm, particle size) using a mobile phase of methanol/phosphate buffer solution (5 mmol l(-1), pH 6.9) with gradient elution. The linear range was 0.1-10.0 mg l(-1); the absolute recoveries ranged from 85.3% to 98.4%; and the limits of detection of the five aromatic amines were between 0.015 and 0.08 mg l(-1). In this work the migration profile of aromatic amines from black plastic bags was investigated at temperatures of 4°C with water, 3% acetic acid solution, 10% ethanol solution and 50% ethanol solution as seafood simulants, respectively. The migration of the five aromatic amines under different conditions showed that residual o-methoxyaniline, p-chloroaniline, aniline and 2,6-dimethylaniline leaching from black plastic bags increased with incubation time. No detectable 3,3´-dimethylbenzidine was found to leach from the bags.

Partially hydrolyzed bamboo (Phyllostachys heterocycla) as a porous Bioadsorbent for the removal of Pb(II) from aqueous mixtures.

A novel porous succinylated bioadsorbent was prepared by the partial enzymatic hydrolysis of bamboo (Phyllostachys heterocycla) and its subsequent modification with succinic anhydride. Pb(II) removal from solutions that also contained sodium chloride and an amino acid was investigated using the bioadsorbent. Enzymatic hydrolysis increased the number of accessible hydroxyl groups and surface area of the raw bamboo, and created many pores within the material. The porous succinylated bioadsorbent exhibited high efficiency for Pb(II) binding. The sodium chloride content significantly decreased the Pb(II) adsorption capacity, whereas a minor effect was observed in the presence of arginine. The experimental data could be accurately described by a pseudo-second-order kinetics model, and the adsorption proceeded via an ion exchange mechanism. Even in a solution containing sodium chloride and arginine, the maximum adsorption capacity of Pb(II) by the porous succinylated bioadsorbent was 99.5 mg/g at 303 K.

Biotransformation of dehydroepiandrosterone (DHEA) with Penicillium griseopurpureum Smith and Penicillium glabrum (Wehmer) Westling.

Microbial transformation of dehydroepiandrosterone (DHEA, 1) using Penicillium griseopurpureum Smith and Penicillium glabrum (Wehmer) Westling has been investigated. Neither fungi had been examined previously for steroid biotransformation. One novel metabolic product of DHEA (1) transformed with P. griseopurpureum Smith, 15α-hydroxy-17a-oxa-d-homo-androst-4-ene-3,17-dione (5), was reported for the first time. The steroid products were assigned by interpretation of their spectral data such as (1)H NMR, (13)C NMR, IR, and HR-MS spectroscopy. P. griseopurpureum Smith was proven to be remarkably efficient in oxidation of the DHEA (1) into androst-4-en-3,17-dione (2). The strain was also observed to yield different monooxygenases to introduce hydroxyl groups at C-7α, -14α, and -15α positions of steroids. Preference for Baeyer-Villiger oxidation to lactonize D ring and oxidation of the 3ß-alcohol to the 3-ketone were observed in both incubations. The strain of P. glabrum (Wehmer) Westling catalyzed the steroid 1 to generate both testololactone 3, and d-lactone product with 3ß-hydroxy-5-en moiety 8. In addition, the strain promoted hydrogenation of the C-5 and C-6 positions, leading to the formation of 3ß-hydroxy-17a-oxa-d-homo-5α-androstan-3,17-dione (9). The biotransformation pathways of DHEA (1) with P. glabrum (Wehmer) Westling and P. griseopurpureum Smith have been investigated, respectively. Possible metabolic pathways of DHEA (1) were proposed.