Ring Opening Polymerization Used for the Production of VOC Free High-Performance Ecofriendly Novel PBZ/PDA/CeO2 Nanocomposites.

This study analyzed the fabrication and characterization of polybenzoxazine/polydopamine/ceria as tertiary nanocomposites. To this end, a new benzoxazine monomer (MBZ) was fabricated based on the well-known Mannich reaction of naphthalene-1-amine, 2-tert-butylbenzene-1,4-diol and formaldehyde under ultrasonic-assisted process. Polydopamine (PDA) was used as dispersing polymer nanoparticles and surface modifier for CeO2 by in-situ polymerization of dopamine with the assistance of ultrasonic waves. Then, nanocomposites (NC)s were manufactured by in-situ route under thermal conditions. The FT-IR and 1H-NMR spectra confirmed the preparation of the designed MBZ monomer. The FE-SEM and TEM results showed the morphological aspects of prepared NCs and illustrated the distribution of CeO2 NPs in the polymer matrix. The XRD patterns of NCs showed the presence of crystalline phases of nanoscale CeO2 in an amorphous matrix. The TGA results reveal that the prepared NCs are classified as thermally stable materials.

Simultaneous improvements in antibacterial and flame retardant properties of PET by use of bio-nanotechnology for fabrication of high performance PET bionanocomposites.

Recently, attentions to the applications of biotechnology and nanotechnology in the polymer industries have been greater than before. Hybrid nanocomposites containing multi-type of nano structures are widely established, but application of biotechnology for in-situ embedment of nanoparticles in polymer matrix is rarely reported. In this study, poly (ethylene terephthalate) (PET) based ternary bionanocomposites containing modified chitosan (phosphorylated chitosan) and nanosilver particles were prepared by simple eco-friendly method. Chitosan was selected as a biopolymer with respect to the biological activity and compatibility with PET. Phosphorylation of chitosan was achieved in order to introduce the phosphorus moieties as a flame retardant agent in PET matrix by using chemical approach. Also a cost-effective and environmentally friendly method was used for the in-situ fabrication and decoration of silver nanoparticles on to phosphorylated chitosan in PET matrix. Effects of the hybrid system (phosphorylated chitosan and silver nanoparticles) on the morphology, thermal behavior and antibacterial properties of the PET samples were investigated by different methods. The microstructure and homogeneity of the samples were analyzed by studying of dispersion of nanoparticles in PET via scanning electron microscopy. The antibacterial properties of PET nanocomposites can be improved by insertion of silver nanoparticles into the bulk of polymer matrix. Obtained results indicated that the PET/phosphorylated chitosan/silver nanocomposites showed a significantly higher growth inhibition rate compared with the PET and PET/phosphorylated chitosan blend. Also the flame retardant properties of PET nanocomposites were drastically enhanced.

Risk of Missed Diagnosis of Primary Open-Angle Glaucoma by Eye Care Providers.

Purpose: To evaluate the efficacy of opportunistic case finding in glaucoma detection and to determine factors associated with failure of glaucoma detection by eye health providers. Methods: This study was conducted on 154 new definite primary open-angle glaucoma (POAG) patients presenting to our glaucoma clinic. A questionnaire was prepared to determine if these subjects had sought eye care up to 12 months before presentation. The type of eye care provider and the principal reason for the visit were probed. The primary outcome measure was the frequency of a correct glaucoma diagnosis in their index visit. The secondary outcomes were factors associated with missed POAG diagnosis. Results: The great majority of study subjects (132 cases, 85.7%) had sought at least one ocular examination within 1 year before presentation. Among these patients, 73 cases (55.3%) had remained undiagnosed after the examination. Among the probed variables, age, gender, visual acuity, visual field defects, intraocular pressure, cup/disc ratio, nerve fiber layer thickness of the worse eye at presentation, and family history of glaucoma were comparable between correctly diagnosed and missed POAGs. The only factors significantly associated with missed POAG diagnosis were lack of significant refractive errors and visiting an optometrist rather than an ophthalmologist. Conclusions: The efficacy of opportunistic case finding for POAG seems to be less than ideal in our settings. Lack of a significant refractive error and visiting an optometrist rather than an ophthalmologist were associated with a missed diagnosis of POAG. These observations reflect the need to adopt policies to improve glaucoma screening by eye care providers.

Production of polyimide ceria nanocomposites by development of molecular hook technology in nano-sonochemistry.

Poly(amic acid), the precursor of polyimide (PI), was used for the preparation of PI/CeO2 nanocomposites (NC)s by ultrasonic assisted technique via insertion of the surface modified CeO2 nanoparticles (NP)s into PI matrix. In the preparation stages, in the first, the modifications of CeO2 NPs by using hexadecyltrimethoxysilane (HDTMS) as a binder were targeted using ultrasonic waves. In the second step, newly designed PI structure was formed from the sonochemical imidization process as a molecular hook. In this step two different reactions were occurred. The acetic acid elimination reaction in the main chain of macromolecule, and the acetylation reaction in the side chains of poly(amic acid) were accomplished. By acetylation process the hook structure was created for trapping of the modified nanoparticles. In the final step the preparation of PI NCs were achieved by sonochemical process. The structural and thermal properties of pure PI and PI/CeO2 NCs were studied by several techniques such as fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (NMR), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and thermal analyses. FT-IR and 1H NMR spectra confirmed the success in preparation of PI matrix. The FE-SEM, TEM, and AFM analyses showed the uniform distribution of CeO2 NPs in PI matrix. The XRD patterns of NCs show the presence of crystalline CeO2 NPs in amorphous PI matrix. The thermal analysis results reveal that, with increases in the content of CeO2 NPs in PI matrix, the thermally stability factors of samples were improved.

Ultrasonic assisted synthesis of nanocomposite materials based on resole resin and surface modified nano CeO2: Chemical and morphological aspects.

In this study, phenol-formaldehyde (PF)/CeO2 nanocomposites (NC)s were prepared by in-situ polymerization of phenol and formaldehyde in alkali solution in the presence of surface modified CeO2 nanoparticles (NP)s by sonochemical assisted synthesis. The morphology and structure of PF/CeO2 NCs were characterized by using fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and thermal analyses methods. It was found that due to the good dispersion of surface modified NPs in polymer matrix and the strong interfacial interaction between the CeO2 NPs and PF matrix, the thermal stability and thermo-mechanical properties of the PF/CeO2 NCs were greatly enhanced. FE-SEM and AFM analyses showed the uniform distribution of CeO2 NPs in PF matrix. The XRD patterns of NCs show the presence of crystalline CeO2 NPs in amorphous matrix. The thermal analysis results reveal that, with increases in the content of CeO2 NPs in PF matrix, the thermally stability factors of samples were drastically enhanced.

Application of zein-modified magnetite nanoparticles in dispersive magnetic micro-solid-phase extraction of synthetic food dyes in foodstuffs.

A simple method for the simultaneous and trace analysis of four synthetic food azo dyes including carmoisine, ponceau 4R, sunset yellow, and allura red from some foodstuff samples was developed by combining dispersive µ-solid-phase extraction and high-performance liquid chromatography with diode array detection. Zein-modified magnetic Fe3 O4 nanoparticles were prepared and used for µ-solid-phase extraction of trace amounts of mentioned food dyes. The prepared modified magnetic nanoparticles were characterized by scanning electron microscopy and FTIR spectroscopy. The factors affecting the extraction of the target analytes such as pH, amount of sorbent, extraction time, type and volume of the desorption eluent, and desorption time were investigated. Under the optimized conditions, the method provided good repeatability with relative standard deviations lower than 5.8% (n = 9). Limit of detection values ranged between 0.3 and 0.9 ng/mL with relatively high enrichment factors (224-441). Comparing the obtained results indicated that Fe3 O4 nanoparticles modified by zein biopolymer show better analytical application than bare magnetic nanoparticles. The proposed method was also applied for the determination of target synthetic food dyes in foodstuff samples such as carbonated beverage, snack, and candy samples.

Peroxisome Proliferator-Activated Receptor-γGene Expression and Its Association with Oxidative Stress in Patients with Metabolic Syndrome.

Regulation of the peroxisome proliferator-activated receptor-γ (PPAR-γ) gene plays an important role in controlling the metabolism of lipids and inflammatory processes. Therefore, it can be associated with the pathogenesis of metabolic syndrome (MetS). The purpose of this study was to determine the expression of this gene in peripheral blood mononuclear cells (PBMC) in patients with metabolic syndrome. Using real-time polymerase chain reaction (PCR), mRNA expression of PPAR-γ was found in PBMC from 37 subjects with MetS and 30 healthy controls. Serum levels of glucose and lipid profiles were measured. The total antioxidant capacity (TAC) was measured using the ferric reducing ability of plasma (FRAP) test. Malondialdehyde (MDA) was determined using a fluorimetric method. Total oxidant status (TOS) in serum was assayed according to oxidation of ferric to ferrous in the presence of methyl orange. Super oxide dismutase (SOD) activity was measured using a Randox kit. Expression of PPAR-γ gene was significantly increased in patients with MetS compared to the control subjects (p=0.002). There was no difference in serum levels of TAC, MDA and SOD between the two study groups, but a significant difference was observed in the TOS (p=0.03). Serum levels of triglycerides and glucose were significantly higher in subjects with MetS. According to the results of our study, an increase in the expression of PPAR-γ in subjects with MetS indicated a possible role of PPAR-γ in the pathogenesis of this disease.

Determination of phenolic compounds content and antioxidant activity in skin, pulp, seed, cane and leaf of five native grape cultivars in West Azerbaijan province, Iran.

In the present work, the phenolic compounds content and antioxidant activity in the skin, pulp, seed, cane and leaf of one international (Muscat) and five native (Hosseini, Ghara Shira, Agh Shani, Ghara Shani and Ghara Ghandome) grape cultivated in West Azerbaijan, Iran were investigated. Ghara Shani grape skin was found to contain the highest content of total phenolic and anthocyanin and cane of Ghara Shani contains the highest amount of flavonoid. A remarkable DPPH radical scavenging activity up to 95% and consequently, the lowest IC50 was found for skin of Ghara Shani. According to RP-HPLC experiments, the highest concentration of phenolic compounds was identified as catechin (945 µg/g), epicatechin (482 µg/g), gallic acid (319 µg/g) and resveratrol (29.8 µg/g) in skin of Ghara Shani, quercetin in cane of Ghara Shani (956 µg/g), rutin in skin of Ghara Shira (298 µg/g) and caffeic acid in cane of Ghara Shira (17.4 µg/g).

Gas chromatographic detection of some nitro explosive compounds in soil samples after solid-phase microextraction with carbon ceramic copper nanoparticle fibers.

In this research, a new solid-phase microextraction fiber based on carbon ceramic composites with copper nanoparticles followed by gas chromatography with flame ionization detection was applied for the extraction and determination of some nitro explosive compounds in soil samples. The proposed method provides an overview of trends related to synthesis of solid-phase microextraction sorbents and their applications in preconcentration and determination of nitro explosives. The sorbents were prepared by mixing of copper nanoparticles with a ceramic composite produced by mixture of methyltrimethoxysilane, graphite, methanol, and hydrochloric acid. The prepared sorbents were coated on copper wires by dip-coating method. The prepared nanocomposites were evaluated statistically and provided better limits of detection than the pure carbon ceramic. The limit of detection of the proposed method was 0.6 µg/g with a linear response over the concentration range of 2-160 µg/g and square of correlation coefficient >0.992. The new proposed fiber has been demonstrated to be a suitable, inexpensive, and sensitive candidate for extraction of nitro explosive compounds in contaminated soil samples. The constructed fiber can be used more than 100 times without the need for surface generation.

An electrochemical nanocomposite modified carbon paste electrode as a sensor for simultaneous determination of hydrazine and phenol in water and wastewater samples.

In this study, we report preparation of a high sensitive electrochemical sensor for determination of hydrazine in the presence of phenol in water and wastewater samples. In the first step, we describe synthesis and characterization of ZnO/CNTs nanocomposite with different methods such as transmission electron microscopy (TEM) and X-ray diffraction (XRD). In the second step, application of the synthesis nanocomposite describes the preparation of carbon paste electrode modified with N-(4-hydroxyphenyl)-3,5-dinitrobenzamide as a high sensitive and selective voltammetric sensor for determination of hydrazine and phenol in water and wastewater samples. The mediated oxidation of hydrazine at the modified electrode was investigated by cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy (EIS). Also, the values of catalytic rate constant (k) and diffusion coefficient (D) for hydrazine were calculated. Square wave voltammetry (SWV) of hydrazine at the modified electrode exhibited two linear dynamic ranges with a detection limit (3σ) of 8.0 nmol L(-1). SWV was used for simultaneous determination of hydrazine and phenol at the modified electrode and quantitation of hydrazine and phenol in some real samples by the standard addition method.

Determination of salmeterol in dried blood spot using an ionic liquid based dispersive liquid-liquid microextraction coupled with HPLC.

A novel analytical method based on the use of a modified dispersive liquid-liquid microextraction (DLLME) technique by ionic liquids has been developed for the first time. This method was applied for the determination of salmeterol in dried blood spot samples from asthmatic patients followed by HPLC system equipped with fluorescence detector. The main novelty of the present work deals with the analysis of salmeterol in dried blood spot with significant advantages with regard to invasive sampling, volume of blood used (<20 µL), storage and transport of biological materials and requirements for special biohazard arrangements. The effects of significant factors in microextraction procedure including extracting and disperser solvents volume, sample pH and salt contents were investigated. Under optimized conditions, the mean recoveries were higher than 90.0% with linear responses about 1.00-500 ng mL(-1) concentration range. The limit of detection (LOD) was 0.30 ng mL(-1) in S/N of 3. Intra-day (n=6) and inter-day (n=3) assay precision showed relative standard deviation lower than 6.0 and 8.5% for studied drug, respectively. The developed microextraction procedure was simpler and faster than conventional extraction techniques and was omitted hazard organic solvents. Finally, the proposed method is suitable for the analysis of salmeterol in dried blood spots from asthmatic patients for therapeutic drug monitoring purpose.

A novel modified carbon paste electrode based on NiO/CNTs nanocomposite and (9, 10-dihydro-9, 10-ethanoanthracene-11, 12-dicarboximido)-4-ethylbenzene-1, 2-diol as a mediator for simultaneous determination of cysteamine, nicotinamide adenine dinucleotide and folic acid.

A carbon paste electrode (CPE) modified with (9, 10-dihydro-9, 10-ethanoanthracene-11, 12-dicarboximido)-4-ethylbenzene-1, 2-diol (DEDE) and NiO/CNTs nanocomposite was used for the sensitive voltammetric determination of cysteamine (CA), nicotinamide adenine dinucleotide (NADH) and folic acid (FA) for the first time. The synthesized materials were characterized with different methods such as XRD, cyclic voltammetry, electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SWV). The modified electrode exhibited a potent and persistent electron mediating behavior followed by well-separated oxidation peaks of CA, NADH and FA. The peak currents were linearly dependent on CA, NADH and FA concentrations using square wave voltammetry (SWV) method in the ranges of 0.01-250, 1.0-500, and 3.0-550 µmol L⁻¹, with detection limits of 0.007, 0.6, and 0.9 µmol L⁻¹, respectively. The modified electrode was used for the determination of CA, NADH and FA in biological and pharmaceutical samples.

Dispersive liquid-liquid microextraction of propranolol enantiomers from human plasma based on the solidification of a floating organic droplet.

BACKGROUND: A dispersive liquid-liquid microextraction based on the solidification of a floating organic droplet was developed and validated for the extraction of propranolol enantiomers from human plasma. The studied enantiomers were extracted from diluted and alkalized plasma samples using 1-undecanol as the extracting solvent. HPLC-fluorescence detection analyses were carried out on a chiral column, using n-hexane-ethanol (80:20, v/v) plus 0.2% triethylamine as the mobile phase, at a flow rate of 0.8 ml/min. The significant factors in the microextraction procedure, including extracting and disperser solvents volume, solution pH and salt contents were optimized by using a central composite design and the response surface methodology. RESULTS: Under optimized conditions, the mean recoveries were approximately 14% with linear responses over the 0.5-100 ng/ml concentration range for both enantiomers. The LOQ was 0.5 ng/ml (S/N = 10). Intra-day (n = 5) and inter-day (n = 3) assay precision (1 and 50 ng/ml) showed RSD lower than 8 and 9.5% for studied enantiomers, respectively. Finally, the method was successfully used for the determination of propranolol enantiomers in plasma samples obtained after single drug administration of racemic propranolol tablet to three healthy volunteers. The plasmatic concentrations of (-)-(S)-PROP were higher than those of (+)-(R)-PROP in all times after oral administration of the racemic drug. CONCLUSION: The obtained results proved that the proposed method is a powerful technique for sample preparation, providing suitable recoveries, efficient cleanup, high selectivity and sensitivity and low consumption of organic solvent for determination of the studied enantiomers in plasma samples after oral administration of the racemic drug to volunteers.

Microextraction techniques in therapeutic drug monitoring.

Therapeutic drug monitoring (TDM), as part of clinical process of medical treatments, is commonly used to maintain 'therapeutic' drug concentrations. TDM is useful to identify the causes of unwanted or unexpected responses, to prevent unnecessary diagnostic testing, to improve clinical outcomes, and even to save lives. The determination of drug concentration in blood samples requires an excellent sample preparation procedure. Recent trends in sample preparation include miniaturization, automation, high-throughput performance, on-line coupling with analytical instruments and low-cost operation through extremely low or no solvent consumption. Microextraction techniques, such as liquid- and solid-phase microextraction, have these advantages over the traditional techniques. This paper reviews the recent developments in microextraction techniques used for drug monitoring in serum, plasma or blood samples.

Fiber-based liquid-phase micro-extraction of mebeverine enantiomers followed by chiral high-performance liquid chromatography analysis and its application to pharmacokinetics study in rat plasma.

The applicability of two-phase liquid-phase micro-extraction (LPME) in porous hollow polypropylene fiber for the sample preparation and the stereoselective pharmacokinetics of mebeverine (MEB) enantiomers (an antispasmodic drug) in rat after intramuscular administration were studied. Plasma was assayed for MEB enantiomer concentrations using stereospecific high-performance liquid chromatography with ultraviolet detection after a simple, inexpensive, and efficient preconcentration and clean-up hollow fiber-based LPME. Under optimized micro-extraction conditions, MEB enantiomers were extracted with 25 µl of 1-octanol within a lumen of a hollow fiber from 0.5 ml of plasma previously diluted with 4.5 ml alkalized water (pH 10). The chromatographic analysis was carried out through chiral liquid chromatography using a DELTA S column and hexane-isopropyl alcohol (85:15 v/v) containing 0.2% triethylamine as mobile phase. The mean recoveries of (+)-MEB and (-)-MEB were 75.5% and 71.0%, respectively. The limit of detection (LOD) was 3.0 ng/ml with linear response over the concentration range of 10-2500 ng/ml with correlation coefficient higher than 0.993 for both enantiomers. The pharmacokinetic studies showed that the mean plasma levels of (+)-MEB were higher than those of (-)-MEB at almost all time points. Also, (+)-MEB exhibited greater t(max) (peak time in concentration-time profile), C(max) (peak concentration in concentration-time profile), t(1/2) (elimination half-life), and AUC(0-240 min) (area under the curve for concentration versus time) and smaller CL (clearance) and V(d) (apparent distribution volume) than its antipode. The obtained results implied that the absorption, distribution, and elimination of (-)-MEB were more rapid than those of (+)-MEB and there were stereoselective differences in pharmacokinetics.

Application of hollow fiber-supported liquid-phase microextraction coupled with HPLC for the determination of guaifenesin enantiomer-protein binding.

A hollow fiber liquid-phase microextraction technique coupled with high-performance liquid chromatography with fluorescence detection was employed for determination and evaluation of the binding characteristics of drugs to bovine serum albumin (BSA). Enantiomers of guaifenesin (an expectorant drug) were investigated as a model system. After optimization of some influencing parameters on microextraction, the proposed method was used for calculation of the target drug distribution coefficient between n-octanol and the buffer solution as well as study of drug-BSA binding in physiological conditions. The developed method shows a new, improved and simple procedure for determination of free drug concentration in biological fluids and the extent of drug-protein binding.

Using dispersive liquid-liquid microextraction and liquid chromatography for determination of guaifenesin enantiomers in human urine.

A simple, rapid, and efficient method, dispersive liquid-liquid microextraction (DLLME) coupled with high-performance liquid chromatography-fluorescence detector, has been developed for the determination of guaifenesin (GUA) enantiomers in human urine samples after an oral dose administration of its syrup formulation. Urine samples were collected during the time intervals 0-2, 2-4, and 4-6 h and concentration and ratio of two enantiomers was determined. The ratio of R-(-) to S-(+) enantiomer concentrations in urine showed an increase with time, with R/S ratios of 0.66 at 2 h and 2.23 at 6 h. For microextraction process, a mixture of extraction solvent (dichloromethane, 100 µL) and dispersive solvent (THF, 1 mL) was rapidly injected into 5.0 mL diluted urine sample for the formation of cloudy solution and extraction of enantiomers into the fine droplets of CH(2)Cl(2). After optimization of HPLC enantioselective conditions, some important parameters, such as the kind and volume of extraction and dispersive solvents, extraction time, temperature, pH, and salt effect were optimized for dispersive liquid-liquid microextraction process. Under the optimum extraction condition, the method yields a linear calibration curve in the concentration range from 10 to 2000 ng/mL for target analytes. LOD was 3.00 ng/mL for both of the enantiomers.

Theoretical study on modeling and prediction of optical rotation for biodegradable polymers containing α-amino acids using QSAR approaches.

The main purpose of the present study was modeling and prediction of the optical rotation ([M](D)) of some biodegradable polymers containing α-amino acids using quantitative structure-activity relationship (QSAR) approaches. In order to attain this goal, the optical rotation of a collection of 53 polymers was selected as a data set. The data set was randomly divided into three sections, training, test and external validation sets. By using dragon software, various descriptors were calculated for all molecules in the data set. The important descriptors were selected applying genetic algorithm-partial least squares (GA-PLS) method. Then an artificial neural network (ANN) was written with MATLAB 7 and used these descriptors as inputs and its output was optical rotation of desired polymers. Then, the constructed network was used for the prediction of ([M](D)) values of validation set. The squared correlation coefficient R² values of the ANN model for the training, test and validation sets were 0.998, 0.996 and 0.996 respectively. The results showed the ability of developed ANN to predict optical rotation of various polymers.

Analysis of n-alkanes at sub microgram per liter level after direct solid phase microextraction from aqueous samples.

This work describes the application of the previously presented solid phase microextraction (SPME) fiber in direct mode for sampling of C10-C20 n-alkanes from aqueous solution. The fiber has simple composition and is constructed from activated charcoal:PVC suspension in tetrahydrofuran. When the composition of the fiber was optimized that the optimum composition was 90:10 (activated charcoal:PVC) for direct mode, whereas it was 75:25 for sampling from the headspace of aqueous samples. This fiber is completely stable in contact with water. The extraction efficiency is improved in the presence of 0.1 M NaCl. The value is between 17.8-38.5% for the first extraction, which better than the efficiency of similar commercial fibers. After seven extractions, all analytes are removed from the aqueous samples nearly 100%. Single fiber repeatability and fiber-to-fiber reproducibility are good and both are less than 13% for all studied alkanes. Finally, direct mode SPME was used in the determination of n-alkanes in the range of sub microg L(-1) without any additional preconcentration procedure. Gas chromatography along with flame ionization detection were used for separation and detection of the studied analytes.