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A novel analytical proposal based on nanofiber-packed solid-phase extraction coupled with high performance liquid chromatography-fluorescence detector (HPLC-FLD) has been successfully developed for determining aflatoxin B1 (AFB1) in foods. Four types of nanofibers, including polystyrene (PS) nanofibers, polypyrrole (PPY) nanofibers, polystyrene-acrylic resin (PS-AR) nanofibers, and polystyrene-polyvinyl pyrrolidone (PS-PVP) nanofibers, were fabricated by electrospinning and utilized to prepare a home-made extraction device. In this study, the factors of different fibers, namely, fiber dosage, pH of extraction solution, type of salt ion, concentration of salt ion, and volume of the eluent were optimized. Under optimized conditions, the method showed good linearity in the range of 0.1-40 ng mL

A novel nanofiber-based solid phase extraction (NFSPE) coupled with HPLC-DAD was developed for the determination of salivary histidine, a new potential index of physiological events. The treatment of the sample was based on a coupling reaction of histidine with the diazotization products of sulfanilic acid and sodium nitrite in a slightly alkaline medium, followed by NFSPE. Nanofibers comprising polystyrene and zinc acetate were used as a novel solid-phase sorbent to extract derived histidine via the chelation of Zn

Mercury (Hg) is one of the harmful pollutants in the atmosphere, and the determination of atmospheric Hg is a difficult task because of its low concentration in the air. Usually, use of an adsorbent for the enrichment of atmospheric Hg must be needed before an analysis of it in the air, but the conventional adsorbent materials are usually expensive and difficult to be prepared. In this study, a new composite membrane fabricated by electrospinning polystyrene integrated with thioglycollic acid was evaluated for the adsorption of Hg in the air. The morphological structure of the novel nanofiber membrane was characterized and their ability to capture atmospheric Hg was also investigated. The adsorptive capacity of nanofiber membrane for atmospheric Hg can be greatly improved after the incorporation of mercapto-function group, which was four times larger than that of the commercial quartz film. Furthermore, the electrospun nanofiber was easier to prepare compared with the traditional Hg adsorption material, sulfhydryl cotton, and exhibited lower pressure drop. It was found that thioglycollic acid-modified electrospun nanofibers can be a potential adsorbent for Hg in the air.

This paper reported a simple, sensitive and environmental-friendly packed nanofiber-based solid phase extraction (PFSPE) technique for the extraction of eight water-soluble B-complex vitamins from infant formula products. The developed PFSPE technique used core/sheath polystyrene/polypyrrole (PS/PPy) nanofibers as adsorbents, and the process involved boric acid compound as complexing reagent which formed conjugated compounds with targets. The PS/PPy nanofibers were prepared in situ polymerization of PPy on the surface of PS nanofibers fabricated by electrospinning. Pretreated samples were analyzed with High Performance Liquid Chromatography coupled with UV Detector system (HPLC–UV). Method validation obtained the intra- precision at 0.6–17.1% and inter-day precision at 0.9–18.2%, respectively, the limits of detection between 0.25 and 0.9 μg g−1, and the linear range of the calibration curves at 0.25–250 μg g−1, and relative recoveries from 76.3 to 126.0%.

Biosensor substrate materials are a key research focus in the field of sensors. Blu-ray discs (BDs) as universal sensor substrates are advantageous in comparison with other substrates (conventional paper and polycarbonate) in terms of easier activity treatment and higher density of reactive groups on the film surface. In this study, a novel and simple microfluidic biosensor based on BD coating film was developed by treating with sodium hydroxide solution and a piece of filter paper at slightly elevated temperatures. There are no significant physical damages to the substrate morphology, and the aging effect is minimal. The unique wetting, optical, and self-cleaning properties of the modified surfaces can be demonstrated in the paper. We have tested this new type of biosensor substrates for assay applications (the determination of total amino acids in tea leaves), which showed excellent performance in terms of sensitivity and reproducibility. The novel biosensor substrate material based on a simple BD coating film displayed preferable merits with easy making, low cost, easy using, and extensive application prospect.

Exposure to heavy metals may affect a vast array of biochemical and nutritional processes in the human body. The toxic manifestations of these metals are caused primarily due to the imbalance betwe...

The simultaneous determination of polyamines and their metabolites in urine samples was achieved by GC-MS in the selected ion monitoring mode. After conjugating with the ion-pair reagent bis-2-ethylhexylphosphate in the aqueous phase, the polyamines in the samples were extracted with polystyrene nanofiber-based packed-fiber solid-phase extraction followed by a derivatization step using pentafluoropropionyl anhydride. With optimal conditions, all analytes were separated well. For analytes of putrescine, cadaverine, N-acetylputrescine and N-acetylcadaverine, the linearity was good in the range of 0.05-500 μmol/L (R

Short-chain fatty acids (SCFAs) are among the active metabolites in biological process both in the intestinal tract and the bioconversion of organic wastes, which has resulted in various human diseases and environmental problems. In order to accurately detect SCFAs, we introduced a novel extraction sorbent. Electrospun polyacrylonitrile (PAN) nanofiber membrane was synthesized, then poly (3, 4-Ethylenedioxythiophene) (PEDOT) was deposited onto the surface of electrospun PAN nanofibers by in situ polymerization. The morphology of the composite PAN/PEDOT nanofiber was characterized by scanning electronic microscopy (SEM) and FTIR spectrum. PAN/PEDOT was used to isolate and concentrate the SCFAs in waste water and fecal samples before gas chromatography mass spectrometry (GC-MS) analysis. The analytical method was evaluated systematically, and low limits of detection (LODs) of 0.34–0.87 μg/L and good linearity (R2 ≥ 0.9953) were obtained. The method was applied successfully for the determination of SCFAs in waste water and fecal samples, with good recovery (87.5–104.6%) and satisfactory reproducibility (relative standard deviation: 6.5–14.1%). The results indicated that the proposed method can be used as a potential approach for the determination of SCFAs with high sensitivity in waste water and biological samples.

Variations in the single nucleotide polymorphisms (SNPs) of the oxytocin receptors (OXTR) indicate individual differences in stress response, social behavior, and psychopathology, but very few paper mentioned OXTR as part of the mechanism linking exposure to air pollution and poor social interactions. The authors investigated the moderating role of Oxytocin receptor (OXTR) rs53576 polymorphism in the relationship between PM

Packed-nanofiber solid phase extraction (PFSPE) combined with gas chromatography-flame ionization detector (GC-FID) was developed for the simultaneous determination of five phthalate esters (PAEs) and bisphenol A (BPA) in fruit juice. The PAEs and BPA was concentrated by PFSPE using polystyrene- pyridine (PS-PD) nanofibers as the sorbent, followed determined by GC-FID. Under this modified procedure, satisfied recoveries in fruit juice sample ranging from 81.9% to 109.6% were obtained. And relative standard deviation values (RSD) were ranged from 1.9 % to 9.8% in orange juice sample. The limits of detection (LOD) and the limits of quantification (LOQ) of five PAEs and BPA were ranged from 0.02 μg/mL to 0.30 μg/mL and 0.06 μg/L to 1.10 μg/L, respectively. This established method was successfully applied to detect real fruit juice samples, which were collected in local supermarket. These results demonstrated the applicability of the established PFSPE-based extraction coupled with gas chromatography method for determination of PAEs and BPA in fruit juice products.

A method for the determination of Rhodamine B in sausage was developed and validated. After extraction of Rhodamine B with acetonitrile from foodstuffs, a novel electrospun polymer nanofibers packed micro-column was used for cleaning and concentrating of the analyte in the sample. High performance liquid chromatography with fluorescence detection (HPLC-Flu) was used for the determination of Rhodamine B in the sample. The mobile phase was composed of 3.0 g L-1 phosphate buffer and methanol (3:7, volume ratio), and the pH was adjusted to 7. 0 with orthophosphoric acid. The results showed that the standard curve was linear over the validated concentrations range of 2-500 ng g-1, and the limit of detection (LOD) and the limit of quantitation (LOQ) for Rhodamine B spiked samples was 0. 2 ng g-1 and 0. 7 ng g-1, respectively. The average recoveries of Rhodamine B were 90.4% -94.3% for sausage, and the relative standard deviation of the method was from 1.7% to 3.8%. This proposed method was applied to real sample, and there was no Rhodamine B found in sausage.

Person Re-Identification (Re-ID) is a challenging task due to large different appearances of people across disjoint views heavily influenced by many factors such as illumination variations, person pose variations, and view variations. Therefore, it is imperative to learn more discriminative feature representation for Re-ID. Existing deep learning models focus on developing feature representation with different scales to characterize person better, which tend to incur interferential and redundant feature output. In this paper, we develop a dynamical and adaptive selective feature fusion module (SFFM) for feature learning, which depends on the input images entirely and facilitates to extract more discriminative features for Re-ID. Moreover, we further improve the discriminative capability of the proposed deep network by incorporating the island loss (IL) with the triplet loss and the softmax loss. The newly proposed loss function is beneficial to increase the distance between those samples belonging to different classes. Validation experiments performed on two standard benchmarks called Market-ISOI and DukeMTMC-reID datasets demonstrate the effectiveness of the proposed method.

The determination of the concentrations of urinary biomarkers of oxidative damage to DNA and RNA is difficult due to the low content of targets and the complex matrix of urine. A method using polystyrene/polypyrrole (PS/PPY) electronspun nanofibers as the adsorbent was introduced to the routine urinary treatment and determination of 8-OHdG and 8-oxoG for the first time. And 2-aminoethyl diphenylborate (DPBA) solution was creatively used in the loading and rinsing steps in order to promote the retention of the analytes as well as remove impurities. Under optimal conditions, 8-OHdG, 8-oxoG and IS were separated very well and exhibited a good linearity in the range of 0.5–50 ng mL−1, with correlation coefficients of R2 > 0.996. Limits of detection (LOD) were 0.058 ng mL−1 and 0.093 ng mL−1, and limits of quantification (LOQ) were 0.195 ng mL−1 and 0.309 ng mL−1, respectively. The recoveries were 88.8–104.9%. The proposed method was so simple and economical that it had the potential to be applied to batch quantitative analysis of 8-OHdG and 8-oxoG in urine. And it was successfully applied to real urine samples of cancer patients.

Based on packed-fiber solid-phase extraction and HPLC-DAD, a simple analytical method for the determination of seven synthetic dyes has been successfully developed. Polystyrene/polypyrrole (PS/PPy) fibers were obtained via electro-spinning of polystyrene skeletal nanofibers, followed by the oxidation with FeCl3 to trigger the polymerization of pyrrole and the deposition of polypyrrole coatings on PS fibrous skeleton fibers. The relationship between the extraction performance of the fibers and the electrospinning process at different humidities was investigated based on morphologic study and BET surface area. In the extraction process, purification, concentration, and desorption could be accomplished in one step. The established method exhibited good sensitivity, selectivity, reproducibility, and good efficiency for synthetic dyes in casual snacks (preserved fruit, flavored yogurt, and fruity hard candy) samples. With optimal conditions, the LODs (S/N = 3) were 2.4 to 21.09 ng mL−1, and linearities were acceptable in liquid matrix and solid matrices. The recoveries were 93.9–103.9%.

The detection of vitamin D in complex samples is challenging because of the instability of vitamin D in sample preparation. To resolve this problem, packed-fiber solid-phase extraction (PFSPE) has been successfully developed for the pre-treatment of samples containing vitamin D2 (D2) and vitamin D3 (D3) in dairy products. Based on PFSPE, vitamin D could avoid oxidation because of the shorter extraction time. The adsorbent materials, polystyrene/polypyrrole (PS/PPy) nanofibers, were prepared by electrospinning of PS and in situ polymerization of PPy on the surface of PS nanofibers. The linearity was within the range of 1-2000 ng mL−1 in dairy solution, and the recoveries were 91.9-109.1% with a relative standard deviation (RSD) < 13.6%. Therefore, the prepared method could be used for the detection of D2 and D3 in dairy products.

A novel magnetic solid phase extraction based on mercaptophenylboronic acid (MPBA)-functionalized Fe3O4-NH2@Au nanomaterial (Fe3O4-NH2@Au-MPBA) was developed for selective separation and enrichment of catecholamines (including dopamine, norepinephrine and adrenaline). Fe3O4-NH2@Au-MPBA nanoparticles were achieved by self-assembly-anchoring MPBA molecules on the surface of Fe3O4-NH2@Au nanocomposites, which were synthesized via a facial ultrasonic auxiliary in situ reduction process. The interaction between cis-diol from catecholamines and boronic acid was reversible and could be flexibly controlled by adjusting pH value. The catecholamines could be quickly adsorbed by Fe3O4-NH2@Au-MPBA in weak alkaline solution (pH 8.0–9.0) and subsequently released in acid solution (pH 1.0–2.0). The process of adsorption and dissociation was very fast. Furthermore, the three catecholamines could be detected in urine from children by high performance liquid chromatography (HPLC) with electrochemical detector. Under optimal conditions, norepinephrine (NE), epinephrine (EP) and dopamine (DA) were separated very well from internal standard and exhibited a good linearity in the range of 2.5–500.0 ng mL−1, with correlation coefficients of r2 &gt, 0.9907. Limits of detection (LOD) (signal to noise = 3) were 0.39, 0.27 and 0.60 ng mL−1 for NE, EP and DA, respectively. Recoveries for the spiked catecholamines were in the range of 85.4–105.2% with the relative standard deviation (RSD) &lt, 11.5%.

The probiotic Lactobacillus plantarum (L. plantarum) were encapsulated with polyvinyl alcohol (PVA) and polyvinyl alcohol/silk fibroin (PVA/SF) nanofibers by electrospinning, respectively. Actually, different concentrations of PVA and SF have significant influence on the morphology of nanofibers, the optimized condition is 6% (w/w) SF and 8% PVA mixed. The L. plantarum on the nanofibers were characterized by scanning electron microscopy (SEM). The different features of PVA/L. plantarum and PVA/SF/L. plantarum nanofibers were proved by thermogravimetric (TGA) and Fourier transform infrared spectroscopy (FTIR). Microbiological tests showed that PVA/SF/L. plantarum exhibited increased survival rates evidently, after being treated in artificial gastric juice at 37 °C for 2 h, and the optical density (OD) value in stable growth period was 2.75, compared with free L. plantarum. The results of this study suggest a novel encapsulation approach that protects probiotic cells during their exposure to adverse environmental and intestinal conditions.

In this paper, we developed a rapid and safe method based on packed-fiber solid-phase extraction (PFSPE) system coupled with gas chromatography-mass spectrometry for the determination of four phthalate esters (PAEs), diethyl-o-phthalate (DEP), dibutyl-o-phthalate (DBP), di (2-ethylhexyl) phathalate (DEHP), di-n-octyl phthalate (DNOP), in urine samples. The PAEs in urine samples (500μL) were rapidly cleaned up from urines using polystyrene (PS) nanofibers packed micro-columns fitted on a PFSPE pretreatment device, which can process up to 12 samples simultaneously in 5min. Under optimum conditions, satisfied recovery and relative standard deviation values (RSDs) were in the range of 80.4-111.7% and 1.5-10.9%, respectively. The limits of detection (LOD) and the limits of quantification (LOQ) were ranged from 0.1 to 0.5ngmL-1 and 0.5-2ngmL-1, respectively. The well controlled matrix effect was also evaluated by comparing the signal response of the pure PAEs standards dissolved in methanol with the signal response of PAEs in the urine matrix. This new method was successfully applied to determine four PAEs in urine samples of overweight and normal-weight children, and an association between phthalates in urines and obesity was observed. Thus, the method seems to be a useful tool for monitoring of the level of urinary phthalate esters and also to support an evidence for further reasearch of obesity.

A selective analytical method based on packed-fiber solid-phase extraction and ultra-high performance liquid chromatography–tandem mass spectrometry (PFSPE-UPLC–MS/MS) has been developed for determination of six β-agonists (clorprenaline, bambuterol, clenbuterol, brombuterol, mabuterol, and penbuterol) in pork tissue. Polystyrene-polymeric crown ether (PS-PCE) composite nanofibers were fabricated by electrospinning and utilized to prepare the homemade extraction columns. With optimal conditions, all analytes were separated very well and the blank pork did not disturb the determination, and the linearity is good in a range of 5.0 μg/kg–25.0 μg/kg. The recoveries were 79.3–110.1%. RSDs for intra-day were in the range of 1.5–10.5% and RSDs for inter-day were 4.7–11.8%. Above all, only 5 mg of sorbent and 200 μL of elution solvent were favorable to directly extract all analytes in a complex matrix. The method is simple and cost-effective, and has the potential to be applied to quantitatively analyze the concentrations of polar species in food samples containing complex matrix.

Background Autism spectrum disorder (ASD) is a complex disorder involving interactions between genetic, epigenetic and environmental factors. Gastrointestinal (GI) disorders are prevalent in the cohort of children with ASD and they have been recognized as a comorbid condition recently. It is of value to monitor GI issues in individuals, and to help further characterize factors that may contribute to GI disorders (in individuals with and without ASD). Due to the biological relevance of short-chain fatty acids (SCFAs) to GI disorders, it is important to develop a rapid and selective detection method capable of identifying and quantifying SCFAs in complex biological samples. Because of low concentration and hydrophilicity of SCFAs, the pretreatment of sample becomes the key step to detection method. We erected and verified a packed-fiber solid-phase extraction (PFSPE) based on Polypyrrole (PPY) nanofibers coupled with gas chromatography–mass spectrometry (GC–MS) to determine SCFAs in urine. The proposed method was applied to detect SCFAs in urine from children with and without ASD, and the results between the 2 groups was compared. Methods PFSPE method was utilized for the direct pretreatment of SCFAs in urine from children. The SCFAs extracted on nanofibers was subsequently eluted with hydrochloric acid ethanol solution and detected by GC–MS. Results Intraday and interday assay CVs were ≤ 10%, and the recoveries was 82.6%–110.5%. Limit of detection (LOD) and limit of quantification (LOQ) were 0.25–2.67 ng/ml and 0.85–8.97 ng/ml, respectively. The level of SCFAs in urine from children with ASD were significantly higher than that from control group. Conclusion The proposed method improves the simplification of sample treatment and displays sufficient analytical sensitivity and selectivity. The assay offers a potential to monitor the SCFAs in urine in clinical and experimental investigation of ASD.

BACKGROUND It has been unclear whether relatively high cortisol and cortisone levels are related to overweight in childhood, parental body mass index (BMI), and family dietary habits. The aim of this study was to compare cortisol and cortisone levels in urine and saliva from overweight and normal children, as well as correlations between children's BMI, parental BMI and family dietary behavior questionnaire score (QS). MATERIAL AND METHODS We analyzed the data from 52 overweight children and 53 age- and sex-matched normal-weight children aged 4-5 years. The concentrations of salivary cortisol (SF), salivary cortisone (SE), urinary cortisol (UF) and urinary cortisone (UE) were measured using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The family dietary behavior QS was answered by the parent mainly responsible for the family diet. RESULTS Average cortisol and cortisone levels were significantly higher in overweight children. There was no significant difference in the ratio of cortisol to cortisone (Rcc) and the marker of 11b-hydroxysteroid dehydrogenase type 2 (11β-HSD2) activities. The results displayed correlations among cortisol, cortisone, and Rcc. Positive correlations were weak-to-moderate between BMI and SF, SE, UF, and UE. There were correlations between BMI and maternal BMI (mBMI), and BMI was significantly associated with QS. CONCLUSIONS Our results suggest that cortisol and cortisone levels are associated with overweight in children, but the 11β-HSD2 activities showed no significant differences. Unhealthy family diet was associated with higher BMI, UF, and UE, and families with maternal overweight or obesity had a higher prevalence of children's overweight or obesity.

A sensitive analytical method based on packed-nanofiber solid phase extraction (PFSPE) and high performance liquid chromatography (HPLC) has been developed for determining chloramphenicol (CAP) in milk. Polystyrene–polyvinylpyrrolidone (PS–PVP) composite nanofibers were fabricated by electrospinning and utilized to prepare a home-made extraction device. With optimal conditions, 12 min of HPLC analysis with isocratic elution was successfully applied to determine CAP in milk. The analyte was separated well and blank milk did not disturb determination, the linearity was good in the range of 0.5–10 μg L−1, and the recoveries were in the range of 97.5–104.0%. The intra-day and inter-day RSDs for spiked samples were respectively 4.6–7.1% and 8.4%, all below 10%. The limit of detection (LOD) was determined to be 0.2 μg L−1. Due to its simplicity, low-cost and time-saving, the method has the potential to be applied to monitor antibiotic residues in dairy products with complex matrices.

Blu-ray discs (BDs) are advantageous in comparison with other optical discs (compact discs and digital versatile discs) in terms of not only their storage capacity but also the high-quality materials fabricated from. We have recently discovered that the "Hard Coat" film of Verbatim BDs is in fact a unique type of polymeric substrates that can be readily activated and adapted for biochip fabrications. Particularly, the Hard Coat film peeled from BDs is optically transparent without any fluorescence background, which can be activated by treating with a common base (1.0 M NaOH) at a slightly elevated temperature (55 °C). The surface density of reactive carboxylic acid groups generated, 6.6 ± 0.7 × 10-9 mol/cm2, is much higher than that on polycarbonate upon UV/ozone irradiation (4.8 ± 0.2 × 10-10 mol/cm2). There are no significant physical damages to the substrate morphology, and the aging effect is minimal. More importantly, the BD substrate can be patterned using either cut-out filter paper masks or microfluidic channel plates; both are lithography-free, bench-top methods that facilitate the device fabrication in a common laboratory setting. With classical biotin-streptavidin binding and DNA hybridization arrays as trial systems, we have also demonstrated this new type of biochip substrates for quantitative assay applications.

We report the improved performance of InGaN/GaN-based light-emitting diodes (LEDs) through the design and the formation of the InGaxNyOz interfacial layer, which maintains high reflectivity of silver and forms good ohmic contact between pristine silver and p-GaN. The interfacial layer was designed and formed by depositing a thin layer of indium tin oxide (ITO) on top of p-GaN, followed by thermal annealing, to enable the interdiffusion and the intermixing of In, Sn, Ga, O, and N atoms. Both electrical and optical performances of the LED with the optimized InGaxNyOz interfacial layer are improved, thus achieving the highest wall-plug efficiency, compared with those LEDs with and without ITO layers at operation current.

Neurotransmitters play a major role in shaping everyday life and functions. Accurate analytical methods are needed for detection of neurotransmitters. Packed-fiber solid-phase extraction (PFSPE) has been developed and seems to be an efficient method. This novel method is based on use of an electrospun polymer device, based on nanofibers. This strategy will be helpful for the development of real-time methods and techniques with high sensitivity to detect target neurotransmitters with high efficiency. Here we provide a brief overview of PFSPE and its applications for the determination of neuro-active molecules.

A novel polystyrene/pyridine composite nanofiber was synthesized and utilized as the sorbent material for the solid-phase extraction of bisphenol A and five common phthalate esters in milk. The method of extraction integrated extraction and preconcentration of target analytes into a single step. Bisphenol A and five common phthalate esters were selected as target compounds for the development and evaluation of the method. The effects of operating parameters for nanofiber-based solid-phase extraction, such as selection and amount of sorbent, the volume fraction of perchlorate (precipitate protein), desorption solvent, volume of desorption solvent, and effect of salt addition were optimized. Under optimal conditions, higher extraction recoveries (89.6-118.0%) of the six compounds in milk spiked at three levels were obtained, and the satisfied relative standard deviation were ranged from 0.6 to 10.9%. The detection limits and quantification limits of the method ranged from 0.01 to 0.06 μg/L and 0.05 to 0.53 μg/L, respectively. Matrix effects were also verified and well controlled in the range of 91.3-109.3%. The new method gave better performance metrics than Chinese standard method and other published methods. Thus, the proposed method may be applied to the analysis of the phthalate esters and bisphenol A in complex matrixes.

This paper put forward a prospective pre-cleanup method of packed-fiber solid phase extraction by using Polypyrrole (Ppy) electrospun nanofibers as the sorbent to simultaneously extract three water-soluble vitamins (i.e., folic acid, cyanocobalamin and riboflavin) in human urine. Primary extraction of target analytes was carried out by loading samples onto the column along with diphenylboronic acid 2-aminoethylester (DPBA) reagent, and then the column should be rinsed with DPBA solution for three times before eluting. The DPBA was innovatively applied as complexing reagent to retain as much of three analytes as possible on the column based on the multi interaction between three vitamins and the boronate affinity reagent, thus improving hydrophobicity of targets and adsorption efficiency through loading and rinsing steps. Under optimized conditions, sample concentration factor was five times with small amount of organic solvent consumed and recoveries between 84.9% to 125.4%, and the lowest detection limit (LOD) between 0.020 to 0.041 μg/mL were achieved. Finally, the urine samples from a group of healthy children were processed with the optimized method. It proved that the proposed method is applicable in the determination of urinary B-vitamins in big samples of people.

Polystyrene nanofibers were coated with copper nanoparticles (CuNPs) by a combination of electrospinning and in-situ reduction of Cu(II) using sodium borohydride as the reductant. The CuNPs on the nanofibers were characterized by energy dispersive spectrometry, scanning electron microscopy and transmission electron microscopy. A cartridge was packed with the nanofibers which then were activated with methanol and water. Glutathione (GSH) is found to quantitatively adsorbed by the packed cartridge at pH 3.0, and then can be desorbed with aqueous 2-mercaptoethanol and detected, after derivatization with ortho-phthalaldehyde, via high performance liquid chromatography with fluorometric detection. Under optimized conditions, the method has a 1.1 ng·mL−1 detection limit and a response that is linear in the 10–1000 ng·mL−1 GSH concentration range. The recoveries of GSH from artificial urine spiked at three levels (80, 400 and 800 ng·mL−1) are in the range of 94.6–98.6% with relative standard deviations (RSD) of

In this work, we report how the Mg doping in the barriers affects the electrical performance of InGaN/GaN-based light-emitting diodes. When compared with the reference device that does not have Mg doped quantum barriers, the turn-on voltage for the proposed device is reduced and the electrical thermal stability is improved. The superior electrical performance is analyzed through the temperature dependent current-voltage and capacitance-voltage characteristics. Meanwhile a reduced depletion length and increased acceptor concentration are achieved in the control devices which is consistent with the simulated results.

The extraction and analysis of catecholamine neurotransmitters in biological fluids is of great importance in assessing nervous system function and related diseases, but their precise measurement is still a challenge. Many protocols have been described for neurotransmitter measurement by a variety of instruments, including high-pressure liquid chromatography (HPLC). However, there are shortcomings, such as complicated operation or hard-to-detect multiple targets, which cannot be avoided, and presently, the dominant analysis technique is still HPLC coupled with sensitive electrochemical or fluorimetric detection, due to its high sensitivity and good selectivity. Here, a detailed protocol is described for the pretreatment and detection of catecholamines with high pressure liquid chromatography with electrochemical detection (HPLC-ECD) in real urine samples of infants, using electrospun composite nanofibers composed of polymeric crown ether with polystyrene as adsorbent, also known as the packed-fiber solid phase extraction (PFSPE) method. We show how urine samples can be easily precleaned by a nanofiber-packed solid phase column, and how the analytes in the sample can be rapidly enriched, desorbed, and detected on an ECD system. PFSPE greatly simplifies the pretreatment procedures for biological samples, allowing for decreased time, expense, and reduction of the loss of targets. Overall, this work illustrates a simple and convenient protocol for solid-phase extraction coupled to an HPLC-ECD system for simultaneous determination of three monoamine neurotransmitters (norepinephrine (NE), epinephrine (E), dopamine (DA)) and two of their metabolites (3-methoxy-4-hydroxyphenylglycol (MHPG) and 3,4-dihydroxy-phenylacetic acid (DOPAC)) in infants' urine. The established protocol was applied to assess the differences of urinary catecholamines and their metabolites between high-risk infants with perinatal brain damage and healthy controls. Comparative analysis revealed a significant difference in urinary MHPG between the two groups, indicating that the catecholamine metabolites may be an important candidate marker for early diagnosis of cases at risk for brain damage in infants.

A solid-phase extraction (SPE) method based on conductive polypyrrole (PPy) nanofibers which were fabricated by electrospinning and in situ polymerization was developed. PPy nanofibers-mediated SPE followed by high performance liquid chromatography (HPLC) was used for the determination of three synthetic estrogens, namely diethylstilbestrol (DES), dienestrol (DIS), or hexestrol (HS) in milk sample. Extraction conditions including extraction nanofibers, donor solution pH and salt concentration were optimized. The target compounds were extracted from a 0.5 mL aqueous sample at pH 5.0 through PPy fibers, and then were eluted with 0.1 mL methanol. After extraction, the eluant was directly injected into an HPLC system for detection. Under the optimized extraction conditions, a large enrichment factor was achieved for three estrogens. The limit of detection (LOD) at a signal to noise ratio (S/N) of 3 ranged from 0.02 to 0.05 µg mL-1 for the estrogens in milk sample.

Neurotransmitters play a major role in shaping everyday life and functions. Accurate analytical methods are needed for detection of neurotransmitters. Packed-fiber solid-phase extraction (PFSPE) has been developed and seems to be an efficient method. This novel method is based on use of an electrospun polymer device, based on nanofibers. This strategy will be helpful for the development of real-time methods and techniques with high sensitivity to detect target neurotransmitters with high efficiency. Here we provide a brief overview of PFSPE and its applications for the determination of neuro-active molecules.

The objective of this study was to investigate the adsorption/desorption performance of volatile organic compounds (VOCs) on electrospun nanofibers. A homemade rational adsorption experimental setup was used to conduct performance tests on the nanofibers measuring the selectivity, adsorption/desorption efficiency, adsorption equilibration time, regeneration and temperature effects. The VOCs adsorbed on different adsorbents, followed by desorption (thermal and/or solvent), were analyzed using capillary gas chromatography. Three nanofibers, including polystyrene (PS) nanofibers, acrylic resin (AR) nanofibers, and polystyrene–acrylic resin (PS–AR) composite nanofibers, three comparison materials, including activated carbons (ACs), carbon nanotubes (CNTs), and carbon fibers (ACFs), as well as ten VOCs, including n-butanol, toluene, chlorobenzene, anisole, nitrobenzene, dichloromethane, ethyl acetate, benzene, acetone and n-hexane, were partly utilized in different performance experiments. The results revealed that the nanofibers exhibited a certain selectivity and the best thermal desorption efficiency compared to all comparison materials. What is more, electrospun nanofibers spent short time reaching adsorption equilibration, favorable regeneration and temperature effect. It showed that electrospun nanofibers can be a potential adsorbent for VOCs.

Cortisol and cortisone are two important glucocorticoids in human body, their interconversion is controlled by two isotypes of 11β-hydroxy steroid dehydrogenase (11β-HSD1 and 11β-HSD2). The ratio of urinary cortisol to cortisone can be used to assess the activity of 11β-HSDs. An analytical method to quantify urinary cortisol and cortisone using high performance liquid chromatographic tandem mass spectrometry following a packed-fiber solid-phase extraction (PFSPE) was developed. The proposed method was validated and applied to determine the urinary cortisol and cortisone concentrations in infants. Linearity was observed in the range of 0.6-150ng/mL for cortisol and 0.8-200ng/mL for cortisone. The intra-day RSD was 2.4-4.5% for cortisol and 3.3-6.2% for cortisone. Inter-day RSD was 3.7-6.6% for cortisol and 4.3-8.2% for cortisone. The recovery was 97.8±4.6% for cortisol and 98.9±4.4% for cortisone. The established method is simple and efficient for the quantification of urinary cortisol and cortisone and for indirectly assessing the activity of 11β-hydroxy steroid dehydrogenase.

Biochemical molecules are substantial bases for the function of nervous system. The concentrations of specific molecules are closely linked to the activity and status of nervous system. This paper summarized our previous work on the relationship be-tween some active biochemical molecules and specific activities in nervous system. The results indicated that the levels of some biochemical substances may reflect the function and regulation of the nervous system, which derived easy, fast and cheap methods for assessing the activity and status in nervous system.

Nanobodies, derived from camelid heavy-chain antibodies, have novel and impactful applications in clinical diagnostics. Our objective is to develop a nanobody-based chemiluminescence immunoassay for sensitive detection of human prealbumin (PA). In this context, a phage display nanobody library is constructed via immunizing dromedary camel with human prealbumin. Three nanobodies have been identified by five successive bio-panning steps. Based on their high expression level and good affinity, two out of three are chosen for further study. Magnetic beads (MBs) were functionalized with PEI by acylamide bond formed between the carboxyl group on the surface of the MB. Then, an anti-PA nanobody (Nb1) can be effectively immobilized onto the surface of the functionalized MB using glutaradehyde as the link. The modified MBs with Nb1 can specifically capture the target PA and reacted with silica nanoparticles with co-immobilized HRP and anti-PA nanobody (Nb2). The concentration of PA was detected by flow injection chemiluminescence. When using MB/PEI as the carrier of anti-PA Nb1, the CL signal significantly increased to 4-fold compared with the signal using MB without PEI modification. The CL signal was further amplified to 5-fold when Si/Nb2 was used as the signal probe. Under optimized conditions, the present immunoassay exhibited a wide quantitative range from 0.05 to 1000 μg L(-1) with a detection limit of 0.01 μg L(-1). The sensitivity of the proposed immunoassay offers great promises in providing a sensitive, specific, time saving, and potential method for detecting PA in clinical settings.