4-Nitro-, 4-methyl-, and 4-methoxy-benzenediazonium fluoroborates are readily dediazoniated with triphenylphosphine or trialkyl phosphites (alkyl = methyl or ethyl) in alcoholic solvents at room temperature in the dark under a nitrogen atmosphere to give the corresponding arenes and the corresponding oxidation product from the phosphine or the phosphites, triphenylphosphine oxide or trialkyl phosphates, respectively, along with a small amount of biaryls. In the reaction with the phosphite, dialkyl arylphosphonate is also formed. The stoichiometry of the reactions and the results of the reactions in deuteriated methanols, together with other evidence, indicate that the reactions proceed by a radial-chain mechanism initiated by single-electron transfer from the trivalent phosphorus compound to the diazonium salt, during which the cation radical is generated from the former. The product distribution shows that this cation radical reacts with the solvent alcohol to give a phosphoranyl radical, which eventually affords the final product, the phosphine oxide or the phosphate, from the phosphine or the phosphite, respectively. The cation radical from the phosphite also undergoes radical coupling with the aryl radical Ar' generated during the reaction to yield dialkyl arylphosphonate via a phosphonium intermediate, whereas no radical coupling of the cation radical from the phosphine with Ar' takes place.

The mono-urea derivative 3 derived from 4-(2-aminoethyl)pyridine and dodecyl isocyanate gelled aromatic solvents, such as p-xylene, tetralin, and benzene, in the presence of Ag(I). The complex formation by the coordination of two equivalents of mono-urea 3 to Ag(I) and the intermolecular hydrogen bonding between urea groups plays important roles for the fibrous self-assembly followed by the gelation.

No abstract

Recombinant fragments of the variable region of antibodies are useful in many experimental and clinical applications. However, it can be difficult to obtain these materials in soluble form after their expression in bacteria. Here, we report an efficient procedure for preparing several variable-domain fragments (Fv), single-chain Fv (scFv), and a diabody (the smallest functional bispecific antibody) of anti-carcinoembryonic antigen (CEA) antibody by overexpression in Escherichia coli in inclusion bodies, using a refolding system to obtain renatured proteins. Two types of refolded Fv were prepared: (i) Heavy and light chains of the immunoglobulin variable regions (VH and VL, respectively) were coexpressed with a dicistronic expression vector (designated Fv(co)); (ii) VH and VL were expressed separately, mixed stoichiometrically, and refolded (designated Fv(mix)). All samples refolded with high efficiency; Fv(co), Fv(mix), scFv, and the bispecific diabody bound to several CEA-positive cell lines, exactly as did soluble Fv fragments secreted by E. coli (Fv(sol)) and the parent IgG. The refolded fragments inhibited binding of the parent IgG to CEA-positive cell lines, indicating that their epitope is identical to that of IgG. The bispecific diabody, which combined variable-region fragments of anti-CEA antibody with variable-region fragments of anti-CD3 antibody, was also prepared using the refolding system. This refolded diabody could bind to lymphokine-activated killer cells. In addition, its cytotoxicity toward human bile duct carcinoma TFK-1 and other several other CEA-positive cell lines was concentration-dependent. Taken together, our results suggest that a refolding procedure can be used to prepare various functional antibody fragments (Fv, scFv, and diabody).

The epoxy monolith with a highly porous structure is fabricated by the thermal curing of 2,2-bis(4-glycidyloxyphenyl)propane and 4,4′-methylenebis(cyclohexylamine) in the presence of poly(ethylene glycol) as the porogen via polymerization-induced phase separation. In this study, we demonstrated a new type of dissimilar material bonding method for various polymers and metals coated with the epoxy monolith. On the basis of scanning electron microscopy (SEM) observations, the pore size and number of epoxy monoliths were evaluated to be 1.1–114 μm and 8.7–48 200 mm –2 , respectively, depending on the ratio of the epoxy resin and cross-linking agent used for the monolith fabrication. Various kinds of thermoplastics, such as polyethylene, polypropylene, polyoxymethylene, acrylonitrile–butadiene–styrene copolymer, polycarbonate bisphenol-A, and poly(ethylene terephthalate), were bonded to the monolith-modified metal plates by thermal welding. The bond strength for the single lap-shear tensile test of stainless steel and copper plates with the thermoplastics was in the range of 1.2–7.5 MPa, which was greater than the bond strength value for each bonding system without monolith modification. The SEM observation of fractured test pieces directly confirmed an anchor effect on this bonding system. The elongated deformation of the plastics that filled in the pores of the epoxy monolith, was observed. It was concluded that the bond strength significantly depended on the intrinsic strength of the used thermoplastics. The epoxy monolith bonding of hard plastics, such as polystyrene and poly(methyl methacrylate), was performed by the additional use of adhesives, solvents, and a reactive monomer. The epoxy monolith sheets were also successfully fabricated and applied to dissimilar material bonding.