Enantiomerically pure sultams (-)-2, (+)-3 and (+)-4 were synthesized.Their uses as new chiral auxiliaries in asymmetric Diels-Alder reactions with diastereoselectivity up to 99∶1 are presented. The relationship between the structure of chiral sultam and the effectiveness of asymmetric induction in Diels-Alder reactions are also discussed.
A piezoelectric immunosensor has been developed for the detection of Hepatitis B surface antigen(HBsAg). Treatment of a Au electrode with cystamine solution results in cysteamine self assemble monolayers(SAMs). Using a bifunctional cross linker, glutaraldehyde, the antibody was immobilized on the electrode surface. The influence factors such as the reaction time of immunoreaction and the concentration of antibody etc. were investigated. Under the optimized experimental conditions, a series standard concentration of HBsAg solutions were analyzed in solution. The frequency shift was linear with the antigen mass concentration in the range of 0 2-12 0 μg/mL. The analysis results of two serum specimens showed that the positive serum and the negative serum could be distinguished easily. Glycine HCl solution(0 2 mol/L) was used for desorption of the bound antigen. The crystal could be regenerated nearly 8 times without detectable loss of activity.
