Zn(II)-Based Mixed-Ligand-Bearing Coordination Polymers as Multi-Responsive Fluorescent Sensors for Detecting Dichromate, Iodide, Nitenpyram, and Imidacloprid.

Coordination polymers (CPs) are organo-inorganic porous materials consisting of metal ions or clusters and organic linkers. These compounds have attracted attention for use in the fluorescence detection of pollutants. Here, two Zn-based mixed-ligand-bearing CPs, [Zn2(DIN)2(HBTC2-)2] (CP-1) and [Zn(DIN)(HBTC2-)]·ACN·H2O (CP-2) (DIN = 1,4-di(imidazole-1-yl)naphthalene, H3BTC = 1,3,5-benzenetricarboxylic acid, and ACN = acetonitrile), were synthesized under solvothermal conditions. CP-1 and CP-2 were characterized by single-crystal X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, elemental analysis, and powder X-ray diffraction analysis. Solid-state fluorescence analysis revealed an emission peak at 350 nm upon excitation at 225 and 290 nm. Fluorescence sensing tests showed that CP-1 was highly efficient, sensitive, and selective for detecting Cr2O72- at 225 and 290 nm, whereas I- was only detected well at an excitation of 225 nm. CP-1 detected pesticides differently at excitation wavelengths of 225 and 290 nm; the highest quenching rates were for nitenpyram at 225 nm and imidacloprid at 290 nm. The quenching process may occur via the inner filter effect and fluorescence resonance energy transfer.

Lignin-based composites for high-performance supercapacitor electrode materials.

With the rapid development of the global economy, the depletion of fossil fuels and the intensification of environmental pollution, there is an increasingly urgent need for new and green electrochemical energy storage technologies in society. In this thesis, ligninsulfonate/polyaniline nanocomposites were synthesized by in situ chemical oxidation using aniline as the monomer, lignin as the template and dopant, and ammonium persulfate as the oxidant. The results showed that the average diameter of the ligninsulfonate/polyaniline nanocomposite was 85 nm, and the composite electrode exhibited good electron conduction ability and excellent capacitive performance by ligninsulfonate doping. The electrode material showed the best electrochemical performance when the ligninsulfonate addition was 0.1 g. The specific capacitance can reach 553.7 F g-1 under the current density of charge/discharge 1 A g-1, which is higher than that of the pure PANI electrode. The composite electrode material has good multiplicative performance and cycling stability, and the capacitance retention rate can be maintained at 68.01% after 5000 cycles at a charge/discharge current density of 10 A g-1 (three-electrode system), and the capacitance retention rate can be maintained at 54.84% after 5000 cycles at a charge/discharge current density of 5 A g-1 (two-electrode system).

Review on the preparation and application of lignin-based carbon aerogels.

Carbon aerogels (CAs) are excellent carrier materials with a large surface area and high porosity. In addition to the above-mentioned wonderful characteristics, aerogel with lignin as a precursor is also a material with high bioactivity and degradability. Lignin carbon aerogels (LCAs) have a wide range of applications, and can be used in supercapacitors, adsorbents and catalysts, etc., but their preparation process is more complex. In this paper, we review the preparation and influencing factors of LCAs, analyze their properties and structural characterization, and aim to provide references for the optimal preparation, effective characterization, and expansion of applications of LCAs.

Formulation and pharmacokinetic evaluation of once-daily sustained-released system of nifedipine with solid dispersion and coating techniques.

A novel sustained-release system was developed for poorly water-soluble drugs by applying solid dispersion (SD) technique to improve the solubility. The SD systems composed of polyvinyl pyrrolidone and stearic acid could not control the release of nifedipine. When the above SD granules were coated with ethylcellolulose (EC10, 45 and 100cp), the dissolution rate extended from 16 to 20 h. When the concentration of EC100cp was increased to 4-6 %, the sustained-release formulation F7 and F8 prepared with 4 % EC100cp and 6 % EC100cp, respectively, could control the drug release in a better manner, namely, they could control drug release in the initial hours with a high cumulative amount of drug at 24 h. The mechanism of drug release from F7 and F8 was diffusion coupled with erosion. When immediate-release capsules was orally administered to rabbits, its absorption was very rapid with a short elimination half-life, while a prolonged maintenance of the plasma drug level up to 24 h was obtained for F7 and F8. Furthermore, the oral bioavailability of F7 and F8 was significantly improved. The results suggested that this novel sustained-release system would be a promising system to improve the solubility and sustain the absorption of poorly water-soluble drugs.

Preparation and the in-vivo evaluation of paclitaxel liposomes for lung targeting delivery in dogs.

OBJECTIVES: The aim of this study was to develop paclitaxel liposomes for a lung targeting delivery system. METHODS: The liposomes composed of Tween-80/HSPC/cholesterol (0.03 : 3.84 : 3.84, mol/mol), containing paclitaxel and lipids (1 : 40, mol/mol), were prepared by a combination of solid dispersion and effervescent techniques, and then subjected to ultrasonication. The pharmacokinetics and biodistribution of liposomal and injectable formulation of paclitaxel in dogs were studied after intravenous administration. KEY FINDINGS: The mean diameter, polydispersity index, zeta-potential and entrapment efficiency of the liposomes were 501.60 ± 15.43 nm, 0.28 ± 0.02, -20.93 ± 0.06 mV and 95.17 ± 0.32%, respectively. The liposomal formulation kept stable for at least 3 months at 6 ± 2°C and didn't cause haemolysis. The liposome carrier decreased the area under the curve and terminal half-life of paclitaxel compared with paclitaxel injection ranging from 0.352 ± 0.031 mg/l*h and 0.0671 ± 0.144 h to 0.748 ± 0.062 mg/l*h and 1.978 ± 0.518 h, respectively. The paclitaxel liposomes produced a drug concentration in the lung that was markedly higher than that in other organs or tissues and was about 15-fold of that of paclitaxel injection at 2 h. CONCLUSIONS: To sum up, these results demonstrated that the paclitaxel liposomes are an effective lung targeted carrier in the treatment of lung cancer.

Preparation and the in vitro evaluation of nanoemulsion system for the transdermal delivery of granisetron hydrochloride.

The objective of this study was to develop and evaluate nanoemulsion system for transdermal delivery of granisetron hydrochloride. Pseudo-ternary phase diagram was constructed to ascertain the concentration range of components of nanoemulsion composed of isopropyl myristate (IPM) as an oil phase, tween 85 as surfactant, ethanol as cosurfactant, water as aqueous phase. The effects of the content of IPM as an oil phase and n-methyl pyrrolidone (NMP) as transdermal enhancer on rat skin permeation of granisetron hydrochloride nanoemulsion were studied in vitro. The results showed that the mean particle size of nanoemulsion ranged from 50.4+/-1.5 to 82.4+/-0.9 nm with homogeneous size distribution. The resulted optimum formulation composed of 2.5% granisetron hydrochloride, 4% IPM, 40% tween 85/ethanol (1 : 1) and 10% NMP showed that the skin permeation rate was the highest (85.39+/-2.90 microg/cm(2)/h) and enhancement of drug permeability was 4.1-fold for transdermal delivery of granisetron hydrochloridein comparison with the control group (20% of tween 85 and 20% of ethanol micelle solution containing 2.5% of granisetron hydrochloride without IPM), and cumulative permeation amount was the highest (891.8+/-2.86 microg/cm(2)) with the shortest lag time (0.11+/-0.02 h) and was stable for at least 12 months. Therefore, the nanoemulsion system developed in this study offers a promising vehicle for the transdermal delivery system of granisetron hydrochloride, which may be as effective as oral or intravenous dosage forms and avoid some difficulties associated with these dosage forms.

Polymer blends used to prepare nifedipine loaded hollow microspheres for a floating-type oral drug delivery system: in vitro evaluation.

The aim of this study was to investigate whether hollow microspheres prepared from polymer blends of polyvinyl pyrrolidone (PVP) and ethyl cellulose (EC) could improve the vitro release behavior of the poorly water-soluble drug nifedipine. Hollow microspheres containing nifedipine were prepared by a solvent diffusion-evaporation method using various ratios of PVP and EC codissolved with drug in ethanol/ether (5:1, v/v). The hollow microspheres could float in release medium for more than 24 h, and floating capacities were not be influenced by mixing PVP. In vitro release profiles of hollow microspheres prepared using EC along showed an initial burst release to some extent, and the cumulative release percentage was less than 55% after 24 h. But, not only the slope but also the shape of the release curves was affected by using mixture of PVP and EC. What's more important, when the ratio (PVP/EC) increased to 1.5:8.5, the cumulative release percentage could be increased to 95.8%. Furthermore, the release rate of microspheres showed a zero order approximate dynamic model and could be expressed by the following equation: Q=3.78t+8.52 (r=0.990). Consequently, hollow microspheres prepared using polymer blends of PVP and EC (1.5:8.5, w/w) could be suitable for floating-type controlled-release delivery systems for the oral administration of nifedipine.

PK and tissue distribution of docetaxel in rabbits after i.v. administration of liposomal and injectable formulations.

A simple and sensitive HPLC method was established and validated for the determination of docetaxel (DTX) in rabbit plasma and tissue samples. Biosamples were spiked with paclitaxel as an internal standard and pre-treated by solid phase extraction (SPE). Sample separation was performed on a reverse-phase HPLC column at 30 degrees C by using a mobile phase of acetonitrile-methanol-0.02 M ammonium acetate buffer (pH 5.0) (20:47.5:32.5, v/v/v) at flow rate of 1.0 mL/min The UV absorbance of the samples was measured at the wavelength of 230 nm. The standard curves were linear over the ranges of 0.02525-2.525 microg/mL for plasma, 1.010-202.00 microg/g for lung, 0.202-20.20 microg/g for spleen, liver and kidney, 0.202-10.10 microg/g for heart and stomach, 0.0505-2.02 microg/g for brain, respectively. The limits of quantification (LOQ) were 10.0 ng/mL in the plasma samples and 20.0 ng/g in the tissue samples, respectively. The analysis method was successfully applied to pharmacokinetics and tissue distribution studies of DTX liposomes and DTX injection after i.v. administration to the rabbits. The results showed that the liposome carrier led to a significant difference in pharmacokinetics and tissue distribution profile compared to the conventional DTX injection.

In vitro and in vivo evaluation of ranitidine hydrochloride loaded hollow microspheres in rabbits.

The objective of this investigation was to develop the hollow microspheres as a new dosage form of floating drug delivery systems with prolonged stomach retention time. Hollow microspheres containing ranitidine hydrochloride (RH) were prepared by a novel solvent diffusion-evaporation method using ethyl cellulose (EC) dissolved in a mixture of ethanol and ether (6:1.0, v/v). The yield and drug loading amount of hollow microspheres were 83.21+/-0.28% and 20.71+/-0.32%, respectively. The in vitro release profiles showed that the drug release rate decreased with increasing viscosity of EC and the diameter of hollow microspheres, while increased with the increase of RH/EC weight ratio. Hollow microspheres could prolong drug release time (approximately 24 h) and float over the simulate gastric fluid for more than 24 h. Pharmacokinetic analysis showed that the bioavailability from RH-hollow microspheres alone was about 3.0-times that of common RH gelatin capsules, and it was about 2.8-times that of the solid microspheres. These results demonstrated that RH hollow microspheres were capable of sustained delivery of the drug for longer period with increased bioavailability.

Bioconversion of ethyl 4-chloro-3-oxobutanoate by permeabilized fresh brewer's yeast cells in the presence of allyl bromide.

Ethyl(R)-4-chloro-3-hydroxybutanoate ((R)-CHBE) are obtained by cetyltrimetylammonium bromide (CTAB) permeabilized fresh brewer's yeast whole cells bioconversion of ethyl 4-chloro-3-oxobutanoate (COBE ) in the presence of allyl bromide. The results showed that the activities of alcohol dehydrogenase (ADH) and glucose-6-phosphate dehydrogenase (G6PDH) in CTAB permeabilized brewer's yeast cells increased 525 and 7.9-fold, respectively, compared with that in the nonpermeabilized cells and had high enantioselectivity to convert COBE to (R)-CHBE. As one of co-substrates, glucose-6-phosphate was preprepared using glucose phosphorylation by hexokinase-catalyzed of CTAB permeabilized brewer's yeast cells. In a two phase reaction system with n-butyl acetate as organic solvent and with 2-propanol and glucose-6-phosphate as co-substrates, the highest (R)-CHBE concentration of 447 mM was obtained with 110-130 g/l of the CTAB permeabilized cells at optimized pH, temperature, feeding rate and the shake speed of 125 r/min. The yield and enantiomeric excess (ee) of (R)-CHBE reached 99.5 and 99%, respectively, within 6 h.