Oriented Antibody Immobilization and Immunoassay Based on Boronic Acid-containing Polymer Brush

High sensitive immunoassay platforms have gained intense attention due to their vital roles in early-stage disease diagnosis and therapeutic information feedback.Although random covalent-binding of antibody has been widely adopted in immunoassays due to its simplicity and effectiveness,it readily loses its activity and fails to exhibit high antigen-binding capacity.In this work,copolymer of zwitterionic sulfobetaine methacrylate (SBMA) and glycidyl methacrylate (GMA) brushes were immobilized onto inert polypropylene (PP) via surface-initiated atom transfer radical polymerization (ATRP) based on biomimetic dopamine pretreatment.Subsequently,boronic acid (BA) groups were covalently bonded via active GMA units,followed by the introduction of oriented immobilization of antibody.Owing to the oriented immobilization of antibody facilitated by BA groups in polymer brush,the bioactivity of antibody is well preserved,which endows the surface with significantly enhanced antigen-binding capacity.Moreover,the existence of SBMA segments in polymer brushes renders the surface high resistance to nonspecific protein adsorption,significantly alleviating the signal interference of antigen recognition.This strategy could find potential applications in developing high sensitive immunoassay platforms based on the different substrates.     

Catalyst-free three-component approach to efficient synthesis of chromeno[4,3-b]pyrrol-4(1H)-one derivatives

A mild, efficient, and environmentally benign one-pot synthesis of functionalized chromeno[4,3-b]pyrrol-4(1H)-ones by a three-component domino reaction of 4-aminocoumarins, arylglyoxal monohydrates, and 1,3-dicarbonyl compounds in refluxing ethanol without the use of catalyst is reported. The present protocol features operational simplicity, short reaction time, good yields, and the absence of aqueous workup procedure and chromatographic separation.     

Rhodium-catalyzed NH-indole-directed ortho CH coupling of 2-arylindoles with diazo compounds via metal carbene migratory insertion

A high regioselective rhodium-catalyzed ortho CH coupling of 2-arylindoles with diazo compounds via NH-indole-directed CH bond activation has been developed. The catalytic reaction features mild reaction conditions, broad substrate scope and good functional group tolerability.     

Attraction behaviour of Anagrus nilaparvatae to remote lemongrass (Cymbopogon distans) oil and its volatile compounds

Utilisation of Anagrus nilaparvatae is a promising and effective method for planthoppers manipulation. Twenty-seven components of remote lemongrass (Cymbopogon distans) oil were identified by GC/MS and nine volatiles were selected for behavioural experiments. In this study, we noted that the remote lemongrass oil was attractive to female A. nilaparvatae at concentrations of 0.1 and 1 mg/L. α-Pinene, β-pinene, eucalyptol, carveol and D-carvone attracted female wasps in the dose-dependent bioassays. Blend 1 (a mixture of eucalyptol, D-carvone, carveol, α-pinene, and β-pinene with ratios of remote lemongrass oil volatiles of 625:80:11:5:3) attracted female wasps at 10 mg/L, while blend 2 (a mixture of the same five volatiles at the same loading ratio) attracted them at 0.1 and 1 mg/L. These results suggested that plant essential oils could be attractants for natural enemies to control pests. The ratios of volatiles in the mixtures affect the attractiveness of the synthetic mixtures.     

Analysis of Polysaccharides in Shii - Take fiom Guizhou

Polysaccharides, special those with physiological actions and nutrition, are widely used as an important resources for food, medicine industries, health etc. Herba Glossogynes Tenuifoliae (Shii-Take) is rich in polysaccharides with physiological actions and nutrition. Guizhou lies to the southwest of China, Natural resources abound in this province, in which there is high output and many species of Shii-Fake. So study in the Shii-Take is favor of reasonably utilizing the natural resources and getting high addvalue products. And what is more, It is necessary for energetically developing west economy.     

Characterization of phosphopeptides from protein digests using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and nanoelectrospray quadrupole time-of-flight mass spectrometry

A two-step mass spectrometric method for characterization of phosphopeptides from peptide mixtures is presented. In the first step, phosphopeptide candidates were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) based on their higher relative intensities in negative ion MALDI spectra than in positive ion MALDI spectra. The detection limit for this step was found to be 18 femtomoles or lower in the case of unfractionated in-solution digests of a model phosphoprotein, beta-casein. In the second step, nanoelectrospray tandem mass (nES-MS/MS) spectra of doubly or triply charged precursor ions of these candidate phosphopeptides were obtained using a quadrupole time-of-flight (Q-TOF) mass spectrometer. This step provided information about the phosphorylated residues, and ruled out nonphosphorylated candidates, for these peptides. After [(32)P] labeling and reverse-phase high-performance liquid chromatography (RP-HPLC) to simplify the mixtures and to monitor the efficiency of phosphopeptide identification, we used this method to identify multiple autophosphorylation sites on the PKR-like endoplasmic reticulum kinase (PERK), a recently discovered mammalian stress-response protein.     

Use of nitrocellulose films for affinity-directed mass spectrometry for the analysis of antibody/antigen interactions

Combination of affinity extraction procedures with mass spectrometric analyses is termed affinity-directed mass spectrometry, a technique that has gained broad interest in immunology and is extended here with several improvements from methods used in previous studies. A monoclonal antibody was immobilized on a nitrocellulose (NC) membrane, allowing the corresponding antigen to be selectively captured from a complex solution for analysis by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). This method was also used to rapidly determine the approximate binding region responsible for the antibody/antigen interaction. The tryptic fragments of antigen protein in buffer were applied to the antibody immobilized on NC film and allowed to interact. The NC film was then washed to remove salts and other unbound components, and subjected to analysis by MALDI-TOFMS. Using interferon-alpha(2a) and anti-interferon-alpha(2a) monoclonal antibody IgG as a model system, we successfully extracted the antigen protein and determined the approximate binding region for the antigen/antibody interaction (i.e., the tryptic fragment responsible).     

Pd(0)/iodide salt-mediated Heck reaction of aryl nonaflates: Application to the synthesis of 2-(1-alkenyl)phenylphosphonates

Iodide salt, such as NaI, KI or n-Bu₄NI (TBAI), rather than bromide or chloride salt, was found to play a key role in the Pd(0)-catalyzed Heck reaction of aryl nonaflates and terminal alkenes. In the presence of PdCl₂(PPh₃)₂, NaI or TBAI in DMF, a class of 2-(1-alkenyl)phenylphosphonates was first synthesized via the reaction of o-phosphonylphenyl nonaflates with alkenes, the yields, regioselectivities and stereoselectivities were much dependent on the nature of the substituents. In case of the aryl nonaflates without bearing the sterically hindered phosphonyl group with the alkenes, the reactions proceeded more smoothly under the same conditions, leading to the linear products regioselectively in good to excellent yields. A rationale for this reaction is discussed.     

The Transition‐Metal‐Like Behavior of B2(NHC)2 in the Activation of CO: HOMO–LUMO Swap Without Photoinduction

It is a current trend to explore multi‐bonded and unsaturated main group compounds that can interact with small molecules, in order to find non‐metal catalysts. Notably, Braunschweig et al. found that diboryne stabilized by N‐heterocyclic carbenes (NHCs) can bind and activate CO. Here we explore the bonding nature of B₂(NHC)₂ and its activation mechanism for CO from a novel theoretical perspective. While the ground state of B₂ is of a single bond, the approach of NHCs excites B₂ to its third excited state of a triple bond with two significant σ‐holes at the two ends. The subsequent electrostatic attraction drives the formation of B₂(NHC)₂. However, only one of the two π bonds (HOMOs) of B₂(NHC)₂ fits to one of the degenerate LUMOs of CO. Interestingly, the strong steric repulsion between CO and B₂(NHC)₂ leads to the HOMO–LUMO swap in the latter. Subsequently, both HOMO and HOMO?1 of B₂(NHC)₂ can effectively interact with the two π* anti‐bonding orbitals (LUMO and LUMO+1) of CO, resulting in substantial electron back‐donation and the ultimate activation of CO.