Dynamic simulation and experimental studies of molecularly imprinted label-free sensor for determination of milk quality marker.

Bovine serum albumin (BSA) has emerged as a biomarker for mammary gland health and cow quality, being recognized as a significant allergenic protein. In this study, a novel flexible molecular imprinted electrochemical sensor by surface electropolymerization using pyrrole (Py) as functional monomer, which can be better applied to the detection of milk quality marker BSA. Based on computational results, with regard to all polypyrrole (PPy) conformations and amino-acid positions within the protein, the BSA molecule remained firmly embedded into PPy polymers with no biological changes. The molecular imprinted electrochemical sensor displayed a broad linear detection range from 1.0 × 10-4 to 50 ng·mL-1 (R2 = 0.995) with a low detection limit (LOD) of 4.5 × 10-2 pg·mL-1. Additionally, the sensor was highly selective, reproducible, stable and recoverable, suggesting that it might be utilized for the evaluation of milk quality.

A chiral multi-shelled mesoporous carbon nanospheres used for high-resolution gas chromatography separations.

Herein, a chiral multishelled mesoporous carbon nanospheres (MCNs) with unique spiral multishelled hollow mesoporous chiral structure is synthesized; the MCNs can be used as stationary phases for high-resolution gas chromatography (GC) and have good separation capacity. The successful preparation of MCNs is verified by a variety of characterizations. In addition, the MCNs-coated capillary column shows excellent separation performance for n-alkanes, n-alcohols, aromatic compounds, and esters, and it has a faster analysis time than the HP-5 commercial capillary column. The chromatography separation performance for various isomers and racemates of the MCNs stationary phase was evaluated, and it showed good separation capability for amino acid derivatives. The MCNs-coated capillary column has been demonstrated to present good reproducibility and stability. In summary, all of the chromatography experiments in this work indicate that this new stationary phase of the MCNs has good application potential for GC capillary separation.

An experimental investigation of the erosion process and morphological characteristics of the tile-back type slope with non-uniform slopes based on a 3D reconstruction method.

Tile-back type slopes comprise ephemeral gullies (EGs) and hillslopes; they are a unique and widely distributed micro-landform in the Loess Plateau region of China. Gully erosion from these landforms is a serious issue, but the micro-landform makes the erosion process and its estimation complex. Quantifying soil erosion processes and their distribution characteristics at different positions on tile-back type slopes will provide a clearer picture for ecological restoration to control further soil degradation. This study investigated the erosion process of tile-back type slope with non-uniform slopes using a 3D photo-reconstruction method during eight successive simulated rainfall events. The results showed that EG erosion began with a chain of intermittent headcuts. When the accumulated rainfall reached 76 mm, serious collapses dramatically increased the amount of sediment by 216% after the first rainfall (cumulative rainfall was about 15 mm). We quantified the sediment contribution of EG erosion (46.20%), rill erosion (35.62%), and inter-rill erosion (18.18%) to total soil loss. The erosion area of the steep slope section and extremely steep slope section accounted for 33.26% and 66.74% of the total erosion area, respectively. Moreover, sediment amounts significantly correlated with morphological parameters, particularly the amount of EG erosion and maximum gully depth, with a correlation coefficient of 0.98. Cumulative gully length and erosion area had the greatest effect on rill erosion, with a correlation coefficient of 0.97. These results provide insight into the qualitative and quantitative understanding of EG erosion process on Loess Plateau of China and an important reference for the rational arrangement of EG control measures.

A chiral metal-organic cage used as the stationary phase for gas chromatography separations.

Chiral metal-organic cages (MOCs) are a new type of porous materials with unique molecular recognition ability, which have received research attention as a chiral stationary phase (CSP) for gas chromatography (GC). Herein, we report the detailed investigation of a chiral MOC ([Cu12(LPA)12(H2O)12], PA = L-phenylalanine, MOC-PA) as a novel stationary phase for GC separations. The MOC-PA capillary column exhibited a high-resolution performance for a wide range of analytes, including n-alkanes, n-alcohols, esters, aromatic compounds and the Grob mixture, positional isomers and racemates. In particular, MOC-PA coated column displayed good resolution and performance for amino acid derivatives. Moreover, the MOC-PA column showed excellent separation repeatability and reproducibility. The relative standard deviation (RSD) values for the retention times were in the range of 0.16-0.30% for run to run (n = 3), 0.31-0.77% for day-to-day (n = 3), and 3.6-4.7% for column-to-column (n = 3), respectively. The experimental results showed that MOC-PA had great potential as a GC stationary phase.

Chiral amorphous metal-organic polyhedra used as the stationary phase for high-resolution gas chromatography separations.

Herein, we describe a new chiral amorphous metal-organic polyhedra used as the stationary phase for high-resolution gas chromatography (GC). The chiral stationary phase was coated onto a capillary column via a dynamic coating process and investigated for a variety of compounds. The experimental results showed that the chiral stationary phase exhibits good selectivity for linear alkanes, linear alcohols, polycyclic aromatic hydrocarbons, isomers, and chiral compounds. In addition, the column has the advantages of high column efficiency and short analysis time. The present work indicated that amorphous metal-organic polyhedra have great potential for application as a new type of stationary phase for GC.

[Preparation and adsorption characteristics of lysozyme-imprinted polymer membrane].

In this work, a novel polymer membrane molecularly imprinted on a silanized glass substrate was prepared. Lysozyme was chosen as the template protein, and acrylamide and N,N'-methylenebisacrylamide were used as the functional monomer and crosslinking agent, respectively. The adsorption equilibrium time, maximum adsorption capacity, specific recognition ability, reusability, and application of the prepared lysozyme-imprinted polymer membrane were investigated experimentally. The prepared polymer membrane exhibited special recognition ability and could quickly adsorb lysozyme. Under optimal conditions, the adsorption equilibrium time of the prepared polymer membrane for lysozyme was 5 min, and the adsorption behavior conformed to the Langmuir adsorption model; the theoretical maximum adsorption capacity was 42.5 mg/g, and the adsorption capacity for an egg sample was 30 mg/g. Additionally, the polymer membrane showed a high selectivity toward the template protein, lysozyme, and exhibited no obvious adsorption of several interfering proteins; the imprinting factor was 3.0. The maximum adsorption capacity of the polymer membrane decreased by 5% after being reused five times. The polymer membrane was used for the adsorption of lysozyme in samples, and good results were obtained. This strategy has potential for the separation and enrichment of target proteins in complex biological samples.

[Preparation and application of melamine molecularly imprinted photonic crystal hydrogel sensor].

In this paper, molecularly imprinted photonic crystal hydrogels (MIPHs) were prepared by combining photonic crystals with molecular imprinting technology. The MIPHs were used as optical sensors for the rapid reorganization and detection of melamine in water samples. In this experiment, melamine was used as a template molecule, and the MIPHs were prepared by successive self-assembly, polymerization, and template removal. Morphological characterization by scanning electron microscopy (SEM) showed that the MIPHs possessed a highly ordered three-dimensional (3D) macroporous structure containing nanocavities. As optical sensors, the MIPHs were able to transform molecular recognition events into fluorescence signals for rapid and highly selective and sensitive recognition of the target molecule. Based on color changes of the MIPHs, the target analyte could be quickly identified by analysis with image software or even by observation with the naked eye. Under optimal conditions, the Bragg diffraction peak of the MIPHs shifted from 563 to 608 nm when exposed to melamine in mass concentrations of 10-11 to 10-6mol/L, whereas there were no obvious peak shifts when it was exposed to structural analogues of melamine.

Association between SRD5A2 polymorphism and hypospadias: a meta-analysis.

Steroid 5a-reductase type-2 (SRD5A2) has been reported to be associated with hypospadias, but the available results are not consistent across studies. Therefore, we conducted a comprehensive meta-analysis to systematically review the association between SRD5A2 gene polymorphisms and hypospadias. Public databases PubMed and Embase were searched before March 1, 2016. Hardy-Weinberg equilibrium (HWE) tests were performed to identify genotypic distribution of single-nucleotide polymorphisms (SNPs) in samples. Among the distribution, we only performed analyses for one SNP (rs523349). The stability of the results was evaluated by sensitivity analysis. Additionally, Egger's test was performed to test a potential publication bias. A total of 6 studies were enrolled. The genotype frequencies were almost consistent with HWE. There were significant differences among SRD5A2 gene polymorphisms and the gene models of rs523349. The results of sensitivity analysis revealed that the results were not unduly influenced by any one study. There was a publication bias in mutational homozygote vs. Wild type homozygote (t = 5.4207, P = 0.0002) or wild type homozygote vs. heterozygote + wild type homozygote (t = 5.2649, P = 0.0002), but no evidence of publication bias was found in other models. SRD5A2 is associated with hypospadias, and SRD5A2 gene polymorphisms might be one of risk factors of hypospadias.

Preparation and evaluation of ethyl [(18)F]fluoroacetate as a proradiotracer of [(18)F]fluoroacetate for the measurement of glial metabolism by PET.

INTRODUCTION: Changes in glial metabolism in brain ischemia, Alzheimer's disease, depression, schizophrenia, epilepsy and manganese neurotoxicity have been reported in recent studies. Therefore, it is very important to measure glial metabolism in vivo for the elucidation and diagnosis of these diseases. Radiolabeled acetate is a good candidate for this purpose, but acetate has little uptake in the brain due to its low lipophilicity. We have designed a new proradiotracer, ethyl [(18)F]fluoroacetate ([(18)F]EFA), which is [(18)F]fluoroacetate ([(18)F]FA) esterified with ethanol, to increase the lipophilicity of fluoroacetate (FA), allowing the measurement of glial metabolism. METHODS: The synthesis of [(18)F]EFA was achieved using ethyl O-mesyl-glycolate as precursor. The blood-brain barrier permeability of ethyl [1-(14)C]fluoroacetate ([(14)C]EFA) was estimated by a brain uptake index (BUI) method. Hydrolysis of [(14)C]EFA in the brain was calculated by the fraction of radioactivity in lipophilic and water fractions of homogenized brain. Using the plasma of five animal species, the stability of [(14)C]EFA was measured. Biodistribution studies of [(18)F]EFA in ddY mice were carried out and compared with [(18)F]FA. Positron emission tomography (PET) scanning using common marmosets was performed for 90 min postadministration. At 60 min postinjection of [(18)F]EFA, metabolite studies were performed. Organs were dissected from the marmosets, and extracted metabolites were analyzed with a thin-layer chromatography method. RESULTS: The synthesis of [(18)F]EFA was accomplished in a short time (29 min) and with a reproducible radiochemical yield of 28.6+/-3.6% (decay corrected) and a high radiochemical purity of more than 95%. In the brain permeability study, the BUI of [(14)C]EFA was 3.8 times higher than that of sodium [1-(14)C]fluoroacetate. [(14)C]EFA was hydrolyzed rapidly in rat brains. In stability studies using the plasma of five animal species, [(14)C]EFA was stable only in primate plasma. Biodistribution studies in mice showed that the uptake of [(18)F]EFA in selected organs was higher than that of [(18)F]FA. From nonprimate PET studies, [(18)F]EFA was initially taken into the brain after injection. Metabolites related to the tricarboxylic acid (TCA) cycle were detected in common marmoset brain. CONCLUSION: [(18)F]EFA rapidly enters the brain and is then converted into TCA cycle metabolites in the brains of common marmosets. [(18)F]EFA shows promise as a proradiotracer for the measurement of glial metabolism.

New approach to fully automated synthesis of sodium [18F]fluoroacetate -- a simple and fast method using a commercial synthesizer.

A simple, rapid and fully automated preparation of sodium [(18)F]fluoroacetate has been developed by taking advantage of the similarities between the reaction pathways of [(18)F]fluoroacetate and [(18)F]-2-fluoro-deoxyglucose (FDG). The automated synthesis of sodium [(18)F]fluoroacetate was achieved with a commercial [(18)F]FDG synthesizer, the TRACERlab MX(FDG). The method produced the desired compound in a short synthesis time (32 min) and with a high and reproducible radiochemical yield (50.2 +/- 4.8%, decay corrected). The radiochemical purity of sodium [(18)F]fluoroacetate was greater than 99%.