Immune Biosensor Based on the ISFETs for Express Determination of Salmonella typhimurium

A new type of immune biosensor was proposed based on ISFET with CeO x instant of Si 3 N 4 gate surface which promotes the sensitivity and stability of the analysis. This biosensor was used for the determination of Salmonella typhimurium in the model solution. It was demonstrated that the sensitivity of the analysis of salmonella was about 2–3 cells mL −1 with the maximal response up to 5×10 5 cells mL −1 . The total time of the measurements can be reduced to 15–20 min if the transducer surface was previously prepared and if one part of the specific antibodies are immobilized on it and the other one labeled by horse radish peroxidase is added to the analyzed solution. Each chip may be reused up to 5 times without signal decreasing after its treatment by 0.1 M HCl for 5 min followed by washing with 5 mM phosphate buffer, pH 7.5. To immobilize immune components the transducer surface was preliminary treated by cystamine with sequential application of glutaraldehyde for covalent binding of Staphylococcal protein A which provides the next immobilization of the specific antibodies with orientation towards the solution.