1849-36-1Relevant articles and documents
β-Lactamase triggered visual detection of bacteria using cephalosporin functionalized biomaterials
Alkekhia, Dahlia,Hopson, Russel,Safford, Hannah,Shukla, Anita,Shukla, Shashank
, p. 11098 - 11101 (2020)
We report the conjugation of a chromogenic cephalosporin β-lactamase (βL) substrate to polymers and integration into biomaterials for facile, visual βL detection. Identification of these bacterial enzymes, which are a leading cause of antibiotic resistance, is critical in the treatment of infectious diseases. The βL substrate polymer conjugate undergoes a clear to deep yellow color change upon incubation with common pathogenic Gram-positive and Gram-negative bacteria species. We have demonstrated the feasibility of formulating hydrogels with the βL substrate covalently tethered to a poly(ethylene glycol) (PEG) polymer matrix, exhibiting a visible color change in the presence of βLs. This approach has the potential to be used in diagnostic biomaterials for point-of-care detection of βL-producing bacteria, helping combat the spread of drug resistant microbes.
Stepwise Mechanisms of the Aminolyses of 4-Nitrophenyl and 2,4-Dinitrophenyl O-Ethyl Dithiocarbonates in Aqueous Ethanol
Castro, Enrique A.,Munoz, Gabriel,Salas, Mirtha,Santos, Jose G.
, p. 987 - 996 (1995)
The reactions of the title substrates with a series of secondary alicyclic amines are subjected to a kinetic study in 44 wtpercent aqueous ethanol, at 25.0 deg C, ionic strength 0.2 M (maintained with KCl).Pseudo-first-order kinetics are found under amine excess.The order in amine obtained is one in the reactions of all amines.The Broensted-type plots for the overall second-order rate coefficients are biphasic with slopes β1 = 0.3 (high pKa), β2 = 0.95 (low pKa) for the aminolysis of the 4-nitro derivative, and β1 = 0.3 and β2 = 0.80 for the aminolysis of the dinitro compound; the pKa values at the curvature center are pK0a 9.8 and 9.5, respectively.From a comparison of these pK0a values with those found in the same reactions in water and the shapes of the Broensted-type plots, it is concluded that these reactions are stepwise, with the formation of a zwitterionic tetrahedral intermediate in the reaction pathway.
Transition metal-free, chemoselective arylation of thioamides yielding aryl thioimidates or N-aryl thioamides
Villo, Piret,Kervefors, Gabriella,Olofsson, Berit
supporting information, p. 8810 - 8813 (2018/08/17)
Reactions of secondary thioamides with diaryliodonium salts under basic, transition metal-free conditions resulted in chemoselective S-arylation to provide aryl thioimidates in good to excellent yields. Equimolar amounts of thioamide, base and diaryliodonium salt were sufficient to obtain a diverse selection of products within short reaction times. Reactions with thiolactams delivered N-arylated thioamides in good yield at room temperature.
