RAPID DETECTION OF SALMONELLA TYPHIMURIUM USING AN IMMUNOELECTROCHEMICAL METHOD COUPLED WITH IMMUNOMAGNETIC SEPARATION

Abstract

Abstract An immunoelectrochemical method coupled with magnetic separation was developed for rapid detection of Salmonella typhimurium. Samples containing Salmonella were mixed with anti-Salmonella coated magnetic beads (ASCMB) and alkaline phosphatase labeled anti-Salmonella (APLAS) simultaneously to form ASCMB-Sdhaoaella-APLAS conjugates by antibody-antigen reaction. The conjugates were separated by a magnetic field and were incubated with phenyl phosphate substrate to produce phenol. The number of Salmonella was determined by measuring the phenol concentration using an amperometric tyrosinase biosensor. This method could be completed within two hours with a detection limit of 5 times 10³ cells/mL under optimized conditions (with ***1 mM MgCl₂, 0.2 μg/mL APLAS and ***l mM phenyl phosphate in pH 7.0 TBS). A linear response on semi-log scale was found for Salmonella pure culture between 5 times 10³ and 1 times 10⁶ cells/mL.