Optimization of the production conditions of tri-GOS and lactosucrose from lactose and sucrose with recombinant ß-galactosidase.

Few studies expressed the ß-galactosidase encoding gene from L. plantarum in E. coli so far. In the present study, the recombinant ß-galactosidase from L. plantarum FMNP01 was used as a catalyst in transgalactosylation to form tri-GOS and lactosucrose. In the presence of lactose and sucrose, six transfer products were formed in the transgalactosylation reaction with recombinant ß-galactosidase L.pFMNP01Gal as a catalyst. Three transfer products were tri-galacto-oligosaccharides (tri-GOS), lactosucrose, and lactulose; the other three transfer products needed to be identified further. Based on a single factor test and response surface methodological approach, the optimal transgalactosylation conditions of the production of tri-GOS and lactosucrose were determined as initial sugar concentration of 50%, lactose: sucrose ratio of 1:2, enzyme concentration of 3 U/mL, and reaction time of 6 h at 50 °C resulting in a maximum tri-GOS concentration of 47.69 ± 1.36 g/L and a maximum lactosucrose concentration of 8.18 ± 0.97 g/L.

Behaviors of Organic Ligands and Phosphate during Biochar-Driven Nitrate Adsorption in the Presence of Low-Molecular-Weight Organic Acids.

A batch experiment was conducted to examine the behavior of nitrate, organic ligands, and phosphate in the co-presence of biochar and three common low-molecular-weight organic acids (LMWOAs). The results show that citrate, oxalate, and malate ions competed with nitrate ion for the available adsorption sites on the biochar surfaces. The removal rate of LMWOA ligands by the biochar via adsorption grew with increasing solution pH. The adsorbed divalent organic ligands created negatively charged sites to allow binding of cationic metal nitrate complexes. A higher degree of biochar surface protonation does not necessarily enhance nitrate adsorption. More acidic conditions formed under a higher dose of LMWOAs tended to make organic ligands predominantly in monovalent forms and failed to create negatively charged sites to bind cationic metal nitrate complexes. This could adversely affect nitrate removal efficiency in the investigated systems. LMWOAs caused significant release of phosphate from the biochar. The phosphate in the malic acid treatment tended to decrease over time, while the opposite was observed in the citric- and oxalic-acid treatments. This was caused by re-immobilization of phosphate in the former due to the marked increase in solution pH over time.

Label-free aptamer-based partial filling technique for enantioseparation and determination of DL-tryptophan with micellar electrokinetic chromatography.

In this study, a simple and reproducible method for enantioseparation and determination of dl-tryptophan (DL-Trp) was developed by using a partial filling technique in combination with MEKC. The corresponding L-Trp specific DNA aptamer was used as a chiral selector. Sodium cholate was used to form the chiral micelles and to enhance the enantioseparation of the enantiomers. Effects of aptamer concentration, filling time, buffer composition, and separation voltage on the enantioseparation were evaluated. The Mg(2+) and Na(+) concentration in separation buffer was found to effectively affect the separation efficiency and reproducibility. Under the optimal conditions, D- and L-Trp were completely enantioseparated in less than 9 min. This aptamer-based partial-filling approach has the potential to be extended to the separation of other enantiomers after the replacement of corresponding specific aptamers.

Analysis of 16 phthalic acid esters in food simulants from plastic food contact materials by LC-ESI-MS/MS.

An RP LC-ESI-MS/MS method for the determination of the migration of 16 primary phthalic acid esters from plastic samples has been developed using distilled water, 3% acetic acid, 10% alcohol, and olive oil as food simulants. Detection limits were 1.6-18.5 µg/kg in distilled water, 1.4-17.3 µg/kg in 3% acetic acid, 1.4-19.2 µg/kg in 10% alcohol, and 31.9-390.8 µg/kg in olive oil. The RSDs were in the range of 0.07-11.28%. The real plastic products inspection showed that only few analyzed samples were phthalates contaminated. Bis-2-ethylhexyl ester and dibutyl phthalate were the common items migrated from the plastic products into food and feeds, but the migration concentrations were far below the limits set by European Union (1.5 mg/kg for bis-2-ethylhexyl ester and 0.3 mg/kg for dibutyl phthalate).

VEGF aptamer/i-motif-grafted multi-functional SPION nanocarrier for chemotherapeutic/phototherapeutic synergistic research.

Chemotherapeutic agents and photosensitizers often suffer from poor tumor selectivity, high side toxicity, or low water solubility. To address these problems, various drug delivery systems (DDS) have been explored but most of them are toxic, difficult to synthesize, or of single function. In order to design a highly biocompatible, conveniently prepared, multi-functional drug delivery system, herein, an aptamer of vascular endothelial growth factor (VEGF) and a cytosine (C)-DNA fragment were grafted on the surface of superparamagnetic iron oxide nanoparticles (SPION), and then a chemotherapeutic agent daunomycin (DNM) and a photosensitizer 5, 10, 15, 20-tetra (phenyl-4-N-methyl-4-pyridyl) porphyrin (TMPyP) were self-assembled with the hybridized VEGF-based DNA structure. By loading DNM and TMPyP, the DDS displayed strong chemotherapeutic/phototherapeutic capability against cancer cells via mechanisms such as mitochondrial dysfunction and ROS elevation, which triggered the apoptosis of the tumor cells. The dual delivery of chemotherapeutical agents and photosensitizers with aptamer/C-rich DNA successfully integrated the functions of pH stimuli-responsive drug release and chemotherapeutic/phototherapeutic modalities into one single system and thus could be considered as an ideal drug delivery vehicle with great potential in clinic.

Is a high-risk clinical target volume required? Evaluation of the dosimetric feasibility based on T staging.

Background: Clinical target delineation is a primary focus in the field of radiotherapy. This study aimed to investigate whether high-risk clinical target volume can be removed in nasopharyngeal carcinoma patients with different T stages. Materials and methods: We designed a test plan without the high-risk clinical target volume for 111 nasopharyngeal carcinoma patients and further compared the test plans with the treatment plans in the parameters of planning target volumes and the radiation dose to normal organs. Results: Our data showed that when high-risk clinical target volume was abnegated, target coverage, conformity indices, and homogeneity indices of planning target volumes and doses of normal organs were not influenced in the T4 nasopharyngeal carcinoma patients, and more than 95% of the high-risk planning target volume area could still be covered by the 60 Gy dose line. However, only some T1-3 patients achieved the ideal dose coverage, and even fewer after induction chemotherapy (62.8% vs. 41.2%, p = 0.018). Gross tumor volume was positively correlated with the target coverage of the original high-risk planning target volume in the test-plan (p = 0.0001). Gross tumor volume can be used to predict whether the target coverage of high-risk planning target volume is more than 95% (area under the curve = 0.868). Conclusion: Omitting high risk clinical target volume can be considered in patients with T4 nasopharyngeal carcinoma according to physical evaluations. However, this approach is only suitable for a specific subset of T1-3 patients.

A novel fluorescent sensor for mutational p53 DNA sequence detection based on click chemistry.

A novel fluorescent sensor for DNA sequence has been designed by taking advantages of copper nanoparticles (CuNPs) selectively formed on double stranded (ds) DNA template and Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reaction. Copper(II) is derived from CuNPs which previously formed on the dsDNA template, and then copper(II) is reduced to copper(I) by ascorbate, which in turn induced CuAAC reaction between the weak-fluorescent compound (3-azido-7-hydroxycoumarin) and propargyl alcohol to form strong fluorescence compounds (1,2,3-triazole compounds). Since CuNPs are accumulated efficiently in the major groove of dsDNA and ssDNA has no groove, it indicates that the proposed sensor owns the merits of low detection limit, high sensitivity and selectivity for mutational p53 sequence detection. Additionally, the method has been successfully applied to recognize the sequence which contains a single-base mismatch in the short human p53 gene fragment. Furthermore, it has also been applied to detect DNA sequence in complex medium (hela cellular homogenate) with satisfactory results.

[Determination of two mouldy compounds in cork by gas chromatography-mass spectrometry].

A simple and fast method for the simultaneous determination of two mouldy compounds, 2,4,6-trichloroanisole (TCA) and 2,4,6-tribromoanisole (TBA), in cork by gas chromatography-mass spectrometry (GC-MS) was established. The analytes were extracted by ultrasonic extraction with methanol, and purified then by solid phase extraction using primary secondary amine (PSA) as solid phase. After concentrating, the sample was analyzed by GC-MS and quantified by the external standard method. The linear ranges were from 10 microg/L to 10 000 microg/L for TCA and TBA, the correlation coefficients (r2) of the calibration curves were above 0.99. The recoveries and the relative standard deviations (RSDs) of TCA and TBA in different kinds of corks were investigated. The recoveries ranged from 88.4% to 97.6% with the RSDs between 1.02% and 4.58% (n = 6). The limits of detection (LODs) were 12 microg/L for TCA and 18 microg/L for TBA, and the limits of quantification (LOQs) were 40 microg/L for TCA and 50 microg/L for TBA. The method is suitable to the determination of TCA and TBA in corks.