Rapid detection of Salmonella typhimurium using an immunoelectrochemical method coupled with immunomagnetic separation

An immunoelectrochemical method coupled with magnetic separation was develo ped for rapid detection of Salmonella typhimurium. Samples containing Salmo nella were mired with anti-Salmonella coated magnetic beads (ASCMB) and alk aline phosphatase labeled anti-Salmonella (APLAS) simultaneously to form AS CMB-Salmonella-APLAS conjugates by antibody-antigen reaction. The conjugate s were separated by a magnetic field and were incubated with phenyl phospha te substrate to produce phenol. The number of Salmonella was determined by measuring the phenol concentration using an amperometric tyrosinase biosens or. This method could be completed within two hours with a detection limit of 5 x 10(3) cells/mL under optimized conditions (with 1 mM MgCl2, 0.2 mu g /mL APLAS and 1 mM phenylphosphate in pH 7.0 TBS). A linear response on sem i-log scale was found for Salmonella pure culture between 5 x 10(3) and 1 x 10(6) ceIls/mL.