The moderating role of human values in planned behavior: the case of Chinese consumers' intention to buy organic food

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Magnetic nanoparticles (MNPs) coated with multilayer polysaccharide shells have been fabricated using a layer-by-layer approach via the alternate deposition of hyaluronan (HA) and chitosan (CS) onto the surface, and the hydrophilic materials were utilized for effective and selective enrichment of glycopeptides in biological samples.Protein glycosylation, one of the most important and ubiquitous post-translation modifications, plays a vital role in regulating various complex biological processes, such as cell-cell interaction, molecular recognition, protein folding, immune response and so forth. 1 Many human diseases have been found to be associated with aberrant N-glycosylation. 2 Currently, mass spectrometry (MS) based techniques have been the premier technology for the characterization of protein glycosylation. Unfortunately, inherent low abundance of glycopeptides, tremendous heterogeneity of each glycosylation site and severe ion suppression caused by the co-existence of non-glycosylated peptides make the direct MS analysis of glycopeptides still a challenge. Hence, an efficient enrichment process prior to MS analysis is needed.To solve these problems, various materials or methods including lectin affinity chromatography, 3a boronic acid affinity chromatography, 3b-d hydrazine beads, 3e Ti(IV)-IMAC 3f and hydrophilic interaction chromatography (HILIC) adsorbents 3g have been utilized for the enrichment of glycopeptides/glycoproteins. Among them, the enrichment strategy based on HILIC has gained increasing popularity and a variety of hydrophilic matrices, such as sepharose, cellulose, ZIC-HILIC beads and click saccharides, have been developed for the selective extraction of glycopeptides. 4 And it was demonstrated that HILIC beads with a high amount of maltose bonded could further improve the profound significance with high selectivity. 5 In recent years, Fe 3 O 4 nanoparticle (MNP) based magnetic separation has become an effective isolation technique, which could achieve better separation compared with conventional approaches, and has attracted much attention in drug delivery, cell separation, bio-separation and enrichment in the biomedical field. 6 Combining the magnetic nano-material with covalently bonded hydrophilic functional molecules could simultaneously achieve the simple and efficient separation of the glycopeptides from the complex peptide mixtures by using magnetic separation. 5,7 Yeh et al. prepared MNPs modified with a hydrophilic polymer by employing spontaneous acid-catalyzed polymerization of zwitterionic monomers, which could be applied for the enrichment of glycopeptides with high selectivity. 7a Recently, a surface initiated atom transfer radical polymerization (SI-ATRP) technique was adopted to obtain the branched PEG brushes hybrid MNPs and then the reactive hydroxyl groups were modified with maltose, which could remarkably increase the amount of immobilized maltose compared to monolayer nanoparticles, and could provide high selectivity and sensitivity for glycopeptide detection. 5...

Iodinated disinfection byproducts (I-DBPs) are highly toxic, but few precursors of I-DBPs have been investigated. Tyrosine-containing biomolecules are ubiquitous in surface water. Here we investigated the formation of I-DBPs from the chloramination of seven tyrosyl dipeptides (tyrosylglycine, tyrosylalanine, tyrosylvaline, tyrosylhistidine, tyrosylglutamine, tyrosylglutamic acid, and tyrosylphenylalanine) in the presence of potassium iodide. High resolution mass spectrometry and tandem mass spectrometry (MS/MS) analyses of the benchtop reaction solutions found that all seven precursors formed both I- and Cl-substituted tyrosyl dipeptide products. Iodine substitutions occurred on the 3- and 3,5-positions of the tyrosyl-phenol ring while chlorine substituted on the free amino group. To reach the needed sensitivity to detect iodinated tyrosyl dipeptides in authentic waters, we developed a high performance liquid chromatography (HPLC)-MS/MS method with multiple reaction monitoring mode and solid phase extraction. HPLC-MS/MS analysis of tap and corresponding raw water samples, collected from three cities, identified four iodinated peptides, 3-I-/3,5-di-I-Tyr-Ala and 3-I-/3,5-di-I-Tyr-Gly, in the tap waters but not in the raw waters. The corresponding precursors, Tyr-Ala and Tyr-Gly, were also detected in the same tap and raw water samples. This study demonstrates that iodinated dipeptides exist as DBPs in drinking water.

Synthetic hydrogels with hydrophobic interactions, which show excellent mechanical performance and good anti-swelling ability in saltwater, have great potential in various industries, such as soft robots, 3D printing, and wearable sensors. Normally, hydrophobic molecules inside a hydrophobic hydrogel tend to aggregate to form a large hydrophobic domain, leading to a phase separation phenomenon because water is a poor solvent of the hydrophobic domain. This aggregation, however, inhibits the adhesion of the hydrophobic hydrogel to various dry materials and thus limits its application in device and sensor industries. In this study, we report the synthesis of hybrid hydrogels with ionically and hydrophobically cross-linked networks. This novel hybrid hydrogel can strongly adhere to various substrates, such as glass, polypropylene, silicone, wood, and polytetrafluoroethylene, with a maximum adhesion strength measured to be 100 kPa. Meanwhile, this hybrid hydrogel can be stretched beyond 8–10 times of its initial length. We attribute this observed strong adhesion and high toughness properties to the synergy of electrostatic interactions and hydrophobic associations. With the strong adhesion and excellent tensile performance, these hydrogels may serve as a model system to explore the strong adhesion mechanism of hydrophobic hydrogels and expand the scope of hydrogel applications.

We report the identification of N-chlorinated dipeptides as chlorination products in drinking water using complementary high-resolution quadrupole time-of-flight (QTOF) and quadrupole ion-trap mass spectrometry techniques. First, three model dipeptides, tyrosylglycine (Tyr-Gly), tyrosylalanine (Tyr-Ala), and phenylalanylglycine (Phe-Gly), reacted with sodium hypochlorite, and these reaction solutions were analyzed by QTOF. N-Cl-Tyr-Gly, N,N-di-Cl-Tyr-Gly, N-Cl-Phe-Gly, N,N-di-Cl-Phe-Gly, N-Cl-Tyr-Ala, and N,N-di-Cl-Tyr-Ala were identified as the major products based on accurate masses, Cl/Cl isotopic patterns, and MS/MS spectra. These identified N-chlorinated dipeptides were synthesized and found to be stable in water over 10 days except N,N-di-Cl-Phe-Gly. To enable sensitive detection of N-chlorinated dipeptides in authentic water, we developed a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method with multiple reaction monitoring (MRM) mode. N-Cl-Tyr-Gly, N,N-di-Cl-Tyr-Gly, N-Cl-Phe-Gly, N-Cl-Tyr-Ala, and N,N-di-Cl-Tyr-Ala along with their corresponding dipeptides were detected in authentic tap water samples. The dipeptides were clearly detected in the raw water, but the N-chlorinated dipeptides were at background levels. These results suggest that the N-chlorinated dipeptides are produced by chlorination. This study has identified N-chlorinated dipeptides as new disinfection byproducts in drinking water. The strategy developed in this study can be used to identify chlorination products of other peptides in drinking water.

Enrichment of glycopeptides by hydrazide chemistry (HC) is a popular method for glycoproteomics analysis. However, possible side reactions of peptide backbones during the glycan oxidation in this method have not been comprehensively studied. Here, we developed a proteomics approach to locate such side reactions and found several types of the side reactions that could seriously compromise the performance of glycoproteomics analysis. Particularly, the HC method failed to identify N-terminal Ser/Thr glycopeptides because the oxidation of vicinal amino alcohol on these peptides generates aldehyde groups and after they are covalently coupled to HC beads, these peptides cannot be released by PNGase F for identification. To overcome this drawback, we apply a peptide N-terminal protection strategy in which primary amine groups on peptides are chemically blocked via dimethyl labeling, thus the vicinal amino alcohols on peptide N-termini are eliminated. Our results showed that this strategy successfully prevented the oxidation of peptide N-termini and significantly improved the coverage of glycoproteome.