We report an aptamer biosensing array for thrombin detection by measuring the electrochemical impedance upon aptamer‐protein formation at the surface of CD‐trodes (GCDTs) in the presence of the redox couple [Fe(CN)6]3?/4?. GCDTs are fabricated from recordable compact discs that contain a fine gold layer. The biosensor is constructed by self‐assembling of a thiol‐modified thrombin binding aptamer (TBA) onto a GCDT surface. The sensor reveals good ligand specificity, recognition in a wide range of thrombin concentrations from 20 nM to 1 µM with a limit of detection of 5 nM. 相似文献
Fused-silica capillaries covalently coated with polypyrrole offer some interesting properties for capillary electrophoresis. The polymeric, surface-bonded coating is chemically stable and reduces the adsorptive properties of the silica surface. At the same time, the weak positive surface charges offer the possibility of creating a strongly anionic surface when poly-sulfates are used as counter-ions. This affords an electroosmotic flow which is largely independent of pH. With sodium dodecyl sulfate in the background electrolyte, this effect is further enhanced. The potential of the approach is demonstrated with the separation of herbicides by micellar electrokinetic chromatography. Repeatability of electroosmotic mobility of less than 1% RSD is achieved. 相似文献
The concept of Galois connection between power sets is generalized from the point of view of fuzzy logic. Studied is the case where the structure of truth values forms a complete residuated lattice. It is proved that fuzzy Galois connections are in one-to-one correspondence with binary fuzzy relations. A representation of fuzzy Galois connections by (classical) Galois connections is provided. 相似文献
A set of 31 structurally different chiral pharmaceutical compounds was used as model analytes for investigation of the enantioselective potential of two immobilized polysaccharide-based chiral stationary phases under normal and reversed phase separation conditions. These chiral stationary phases differed in the polymeric backbone, amylose or cellulose, but possessed the same derivatization functionality. The results showed that the tris(3,5-dimethylphenylcarbamate) of amylose and cellulose have very broad, and often complementary, enantiorecognition abilities. In general, normal phase separation mode seemed to be more advantageous for separation of the majority of studied pharmaceuticals no matter if amylose- or cellulose-based columns were used. However, in certain cases the reversed phase separation system yielded better results. The combination of these two immobilized chiral stationary phases offers a powerful tool for enantioseparation of different types of pharmaceuticals in the normal and/or reversed phase mode.
Polysaccharide‐based chiral stationary phases can be used for the enantioselective separation of a wide range of structurally different compounds. These phases are available with chiral selectors coated or immobilized on silica gel support. The means of attachment of the chiral selector to the carrier can influence the separation performance of these stationary phases. This paper deals with evaluation of differences in the separation abilities of coated Chiralpak AD‐RH versus immobilized Chiralpak IA amylose‐based stationary phases in the reversed–phase mode of high–performance liquid chromatography. A set of chiral analytes was separated under acidic and basic conditions. Differences were observed in the enantioseparation potential of the tested phases. The linear‐free energy relationship and additional evaluation of ionic interactions were used to ascertain whether the interactions that participate in retention and enantioseparation are affected by the means of preparation of these phases. All the interactions covered by the linear‐free energy relationship were significant for the studied phases and their absolute values were almost always higher for the coated phase. Ionic interactions were found to be more important on the immobilized stationary phase but did not contribute to any improvement in the enantioselective separation performance. 相似文献