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Dominguez Abbott posted an update 1 week, 3 days ago
This study aims to investigate in depth the mechanism of acrylamide formation in coffee during roasting. For this purpose, a comprehensive kinetic model including the elementary steps for acrylamide formation was proposed. The changes in sucrose, reducing sugars, free amino acids, asparagine, acrylamide, 3-deoxyglucosone, methylglyoxal, glyoxal, and 5-hydroxymethylfurfural were monitored in coffee during roasting at 200, 220 and 240 °C. Dominant pathways of complex reactions leading to acrylamide were unravelled by means of multiresponse kinetic modelling approach. The results of the model indicated that sucrose degrades into glucose and a reactive fructofuranosyl cation. Interestingly, glucose takes part mostly in the formation of intermediates, glyoxal and especially 3-deoxyglucosone rather than acrylamide formation. On the other hand, fructofuranosyl cation contributed mostly to the formation of 5-hydroxymethylfurfural which was found to be the most important intermediate precursor of acrylamide formed in coffee during roasting. Overdoses of SO2 and its derivatives (SO32-/HSO3-) in food or organisms are harmful to health. To detect SO32-/HSO3-, a novel NIR fluorescent probe 1, based upon the intramolecular charge transfer (ICT) mechanism, was developed. This probe was easily synthesized, and gave noticeable colorimetric and linear fluorescence changes at 690 nm after reaction with sulfite from 3.13 to 200 µM. Moreover, probe 1 displayed high sensitivity (LOD = 0.46 µM), excellent selectivity (among 13 kinds of anions and 3 kinds of biothiols) and quick response (within 30 min) towards SO32-/HSO3-. The SO32-/HSO3- sensing mechanism was confirmed as the Michael addition reaction. Furthermore, the probe showed wide applications for measuring SO32-/HSO3- in real samples, including sugar, tap water, wine and traditional Chinese medicine. The probe could also be used to detect SO32-/HSO3- in mitochondria of HepG2 cells and zebrafish, which suggested potential application for monitoring SO2 derivatives in clinical diagnostics. Antibody charge heterogeneity is one of the major product-related variants in recombinant biopharmaceuticals, which has been commonly monitored by imaged capillary isoelectric focusing (icIEF). Due to the challenges with sample recovery and fractionation, other charge-based analytical approaches have been explored as complementary methods allowing for further detailed charge variant characterization. This study describes the utilization of free flow electrophoresis (FFE) fractionation in combination with other analytical techniques, such as mass spectrometry for monoclonal antibody acidic variants characterization. Selleck Valproic acid The preparative FFE technique allowed for continuous sample separation and fluid phase fractionation of antibody charge isoforms. The monoclonal antibody starting material was fractionated by FFE, followed by purification and characterization. icIEF analysis demonstrated the purity of the fractions and comparability of the charge profiles between these two techniques. The intact molecular mass analysis revealed that glycation modification was highly enriched in the acidic fractions. SEC UV/Fluorescence method was developed to assess the levels of aggregation and fluorescent advanced glycation end-products (AGEs). Detailed peptide map was performed and revealed that acidic fractions were enriched in AGEs, methionine, tryptophan, histidine oxidation, asparagine deamidation, lysine glycation, carboxymethyl lysine, glycine to aspartic acid substitution compared to the main peak and starting material. The results indicate that acidic variants can account for a variety of low-level modifications present as very heterogeneous forms. During routine screening of illegal adulterants in health supplements, a novel sildenafil analogue was discovered, and subsequently isolated by recrystallization. Its structure was elucidated by extensive analyses of high resolution mass spectrometry (HRMS), one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) data. The analogue was finally determined as hydroxycarbodenafil, featuring a hydroxyethyl group instead of an ethyl group on piperazine ring in comparison with carbodenafil. V.Puerarin, an important isoflavone, has been widely used for the treatment of angina and hypertension. In this work, we developed a novel electrochemical sensor for the detection of puerarin based on the hybrid of reduced graphene oxide (RGO) and molecularly imprinted polymer (MIP). The RGO/MIP sensor functions by target puerarin recognition and electro-oxidization via a two-proton and two-electron process, enabling the detection of puerarin with good selectivity and high sensitivity. The MIP layer was integrated on the surface of RGO by the electro-co-polymerization of o-phenylenediamine (monomer) and puerarin (template), resulting in high surface area, binding capacity, good conductivity and faster mass transfer. The nanostructure of the RGO/MIP hybrid was demonstrated using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Experimental conditions involved in the sensor fabrication process were evaluated. Under the optimized condition, a wide linear range (0.02 μM ∼ 40 μM) and a low detection limit (0.006 μM) were achieved. The sensor was applied to detect puerarin in human urine and injection samples, and the result was comparable with that of the gold standard method of high-performance liquid chromatography (HPLC), indicating a promise in the further application to pharmacokinetics or therapeutic drug monitoring. Lung cancer (Lca) is one of the malignant tumors with the fastest morbidity and mortality increase and the greatest threat to human health and life. The incidence of non-small cell lung cancer (NSCLC) in the nonsmoking female has increased recently. However, its pathogenesis is still unclear, and there is an urgent need for clinical diagnostic biomarkers, especially for early diagnosis. A nontargeted lipidomic approach based on ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF/MS), as well as two machine learning approaches (genetic algorithm and binary logistic regression) was used to screen candidate discriminating lipids and define a combinational lipid biomarker in serum samples to distinguish female patients with NSCLC from healthy controls. Moreover, the candidate biomarkers were verified by using an external validation sample set. Our result revealed that fatty acid (FA) (204), FA (220) and LPE (204) can serve as a combinational biomarker for distinguishing female patients with NSCLC from healthy control with good sensitivity and specificity.