Preparation of poly (sodium acrylate) polymer-brush-grafted polystyrene-divinylbenzene resins and their adsorption performance toward nitrogen-containing organic compounds

Preparation of p-phenylenediamine modified polymer brush grafted PS-DVB materials for highly selective adsorption of flavonoids

Synthesis of polyacrylamide immobilized molybdenum disulfide (MoS 2 @PDA@PAM) composites via mussel-inspired chemistry and surface-initiated atom transfer radical polymerization for removal of copper (II) ions

Distributions of petroleum compounds in crude oils can be altered during secondary migration by adsorption and other chromatographic processes. Trends in distributions of alkanes and nitrogen-containing compounds among oils may indicate migration pathways when used in conjunction with structural and lithologic maps. Several crude oils which were produced from reservoir sans of the Morrow Formation in western Kansas and eastern Colorado were analyzed for hydrocarbons and nitrogen-containing organic compounds. Deasphalted oils were fractionated into saturate, aromatic, and polar fractions using a thermionic specific detector, which responds specifically to nitrogen-containing organic compounds. Lithologically Morrow sands and shales contain abundant clay minerals which potentially expose active adsorptive surfaces to petroleum compounds as migration of the crude oil proceeds. The fluvio-deltaic depositional environment of the sands provides clay minerals along probable flow paths in the form of clay drapes or a s gradational facies changed in silt and clay content. Differences in both alkane and nitrogenous compound profiles of crude oils from the study area exhibit possible migration-induced alteration of the oils.

Preparation of polymeric silica composites through polydopamine-mediated surface initiated ATRP for highly efficient removal of environmental pollutants

The formation of nitrogen-containing organic compounds is crucial for understanding chemical evolution and the origin of life in the interstellar medium (ISM). In this study, we explore whether acrylonitrile (AN) and pyrrole (Py) can form new nitrogen-containing compounds after single-photon ionization in their gaseous clusters by vacuum ultraviolet (VUV)-infrared (IR) spectroscopy and theoretical calculations. The results show that a strong linear H-bond is formed in neutral AN-Py, while cyclic or bicyclic H-bonded networks are formed in the neutral AN-Py2 cluster. It is found that the structure containing a new C-C covalent bond between two moieties in (AN-Py)+ is formed besides the formation of H-bonded structures after AN-Py is ionized by VUV light. In (AN-Py2)+ cluster cations, new C-C or C-N covalent bonds tend to be formed between two Py, with (Py)2+ as the core in the cluster. The results reveal that new covalent bonds are more likely to be formed between two Py species when AN and Py are present in the cationic clusters. These results provide spectroscopic evidence of the formation of new nitrogen-containing organic compounds from AN and Py induced by VUV, which are helpful for our understanding of the formation of diverse prebiotic molecules in interstellar space.

Compositional analysis of bio-oil derived from pyrolysis of seaweed

The objective of the study is to identify the effect of no-till technologies for processing agrochernozems on the heterogeneity of the compared soil layers in terms of protease and urease enzyme activity. The studies were carried out under the conditions of a production experiment laid out in the Shilinskoye agricultural production cooperative in the Krasnoyarsk forest-steppe located within the Chulym-Yenisei denudation plateau of the southwestern outskirts of Central Siberia (56°37' N and 93°12' E). The soil of the experimental plot was leached high-humus medium-deep light clayey chernozem on red-brown clay. The experimental soil was characterized by: humus content of 5.9 %, neutral reaction of the environment (pHH2O 6,8). The sum of absorbed bases was from 60 to 62 mg-eq/100 g of soil. In production crops, soil samples were taken three times during the vegetation season from the 0–5 and 5–20 cm layers using the snake method. The sample size was 15 individual samples. The norm, in accordance with the WMO regulations, was calculated for a 30-year period (1981–2010). The experimental design consisted of the following variants (processing methods): 1 – zero; 2 – minimum; 3 – moldboard (st). A significant differentiation of the studied agrochernozem layers was revealed when using minimum tillage technologies. Periods with a deficit of atmospheric moisture had a significant effect on the amount of proteolysis. An increase in moisture was accompanied by a decrease in proteolytic activity (r = –0.5 ... –0.63) when using surface disking, whereas under no-till conditions a direct effect of moisture on the level of hydrolysis of nitrogen-containing organic compounds was found (r = 0.61 ... 0.68). An increase in protease activity was accompanied by a significant decrease in difficult-to-hydrolyze nitrogen-containing compounds when using surface disking (r = –0.57 ... –0.71). During periods with excess moisture, significant differences in the level of urease activity were also found, mainly when using minimum tillage technology. The transformation of easily hydrolysable nitrogen-containing organic compounds was associated with the level of urease activity.

Chemical characteristics and sources of nitrogen-containing organic compounds at a regional site in the North China Plain during the transition period of autumn and winter

Synthesis of a novel restricted access chiral stationary phase based on atom transfer radical polymerization and click chemistry for the analysis of chiral drugs in biological matrices

We present a detailed picture to screen general ligands from simple chemicals for fabricating affinity surface to glycosidase enzymes. The surface was constructed by grafting poly(2-hydroxyethyl methacrylate) (PHEMA) brush on SPR gold chip via surface-initiated atom-transfer radical polymerization, after which poly(methoxyethyl methacrylate) (PMEMA) and poly(oligo(ethylene glycol) methacrylate) (POEGMA) brushes were also prepared for comparison. SPR measurements were adopted to monitor the early-stage adsorption of two glycosidases and three other typical proteins. PHEMA resists the adsorption of lysozyme, bovine serum albumin, and fibrinogen, while it is capable of specifically adsorbing β-glucosidase (GLU) and β-galactosidase (GAL). These are quite different from the nonspecific adsorption of PMEMA and the anti-nonspecific adsorption of POEGMA to the studied proteins, because PHEMA is the acceptor substrate of the glycosidases. About 69.6 and 93.7 ng/cm(2) of GAL and GLU are adsorbed on the PHEMA brush surface, of which more than 49.6 ng/cm(2) is remained after washing with PBS. The specific adsorption process is appropriately described by Freundlich isothermal model rather than Langmuir one, and is also indicated to be spontaneous, endothermic, and entropy driven through thermodynamic studies. Taking into account all stated results above, we propose that molecular recognition takes place between the hydroxyl groups of PHEMA and the active sites of glycosidases, which subsequently enables the oriented adsorption of glycosidases on the brush surface. The adsorbed enzyme can be effectively eluted with 1.0 M aqueous solution of ethanol. Our findings open the door to the further development in the design of novel acceptor substrate-ligand affinity chromatography for enzyme purification.

The development of new materials for fast and sensitive protease assay is in demand for timely diagnosis of diseases, such as cardiovascular disease, cancers, and Alzheimer disease. Herein, poly(methacrylic acid) (PMAA) brushes were synthesized from the surfaces of silica nanoparticles via surface-initiated atom transfer radical polymerization (ATRP), and functionalized with series of proteolytically cleavable peptides for highly sensitive protease assay. Upon the proteolytic cleavage of the peptides, a short peptide fragment with fluorescent tag (GGK-FITC) is released to the solution, which can be easily detected with a benchtop fluorescence microscope. The grafting densities of PMAA brushes and peptides can be readily tuned by controlling the monomer concentrations of sodium methacrylate in the ATRP reaction. Because of the three-dimensional architecture of PMAA brushes, the loading amount of peptides can reach 21.4% of the total weight of functionalized silica particles (22.4 peptides/nm2), which is much higher than direct immobilization on silica nanoparticles without polymer brushes. Because of the high loading density of peptides, the limit of detection (LOD) of trypsin can reach 1.4 pM in buffer solution or 2.6 nM in nondiluted serum. By rational design of peptide substrates, the peptide-functionalized PMAA brushes can be readily expanded to detect other proteases, such as matrix metalloproteinase-2 (MMP-2), a virtual biomarker for many cancers, with an LOD of 1.1 pM. The proteolytically cleavable peptide-functionalized PMAA brushes offer a starting point for fast and sensitive protease assay.

Functionalized Si3N4 nanoparticles modified with hydrophobic polymer chains by surface-initiated atom transfer radical polymerization (ATRP)

Surface-initiated atom transfer radical polymerization (ATRP) of tert-butyl acrylate was carried out directly from a nonmodified poly(vinylidene fluoride-co-trifluoroethylene) [P(VDF-co-TrFE)] film surface to give a polymer brush, which was further converted to a poly(acrylic acid sodium salt) brush by hydrolysis. A hydrophilic surface was successfully created at the outermost surface of P(VDF-co-TrFE) film without any change in the bulk physical properties. Also the effect of surface nanotexture formation on wettability was investigated.

In this study, we developed a novel microcarrier to enhance the production of anchorage-dependent mammalian cells in large scale by preserving them from the effects of shear forces and to enhance their removal from the surface without using proteolytic enzymes and chelating agents. This ‘thermosensitive microcarrier’ was synthesized by the grafting thermoresponsive molecule, N-isopropylacrylamide (NIPAAm), to the crosslinked poly(2-hydroxyethyl methacrylate) (PHEMA) beads by surface-initiated atom transfer radical polymerization. NIPAAm was polymerized on bromine-activated beads’ surfaces to prepare PHEMA-g-PNIPAAm microcarriers. Then, they were chemically characterized by attenuated total reflectance Fourier transform infrared and electron spectroscopy for chemical analysis. Surface morphologies were further investigated by scanning electron microscope and atomic force microscopy techniques. The results of characterization studies confirmed that PNIPAAm was successfully grafted onto PHEMA beads by the means of atom transfer radical polymerization reaction. The cellular activities of PHEMA-g-PNIPAAm microcarriers were evaluated at static and dynamic culture conditions by using two types of cell lines with different morphology, i.e. L929 mouse fibroblasts and HS2 epithelial human keratinocytes. The microcarriers exhibited better cell adhesion and proliferation characteristics for both cell lines. Although their thermally induced cell detachment efficiencies are lower than that of trypsinization, thermally harvested cells preserved their surface morphologies and proliferation characteristics.

Development of a peptide microarray-based metal-enhanced fluorescence assay for ultrasensitive detection of multiple matrix metalloproteinase activities by using a gold nanorod-polymer substrate