Flow-injection assay of the pathogenic bacteria using lectin-based quartz crystal microbalance biosensor

A novel flow-injection assay of the pathogenic enterobacteria using novel lectin-based quartz crystal microbalance (QCM) biosensor has been proposed. The biosensing part of the analytical device contained the lectins – Concanavalin A, lectins from Ulex europeus, Maackia amurensis, Lens culinaris, wheat germ agglutinin – immobilized on the gold surface of quartz crystal electrode which served as a transducer. The immobilization of lectins was carried out using amine coupling on the surface of the crystal modified with 11-mercaproundecanoic acid. The biosensor makes it possible to identify the presence of different bacterial using the lectins immobilized on the surface of QCM crystal which bind specifically to the certain oligosaccharides present on the cell wall of the bacteria injected. The working conditions of the biosensor – pH of buffer solutions, concentration of the immobilized lectins, dilution of the bacterial cells, regeneration solution and flow rate – were optimized. The use of solution of glycine (pH 2.5) makes it possible to remove the formed complex from the crystal surface to make it reusable and ready for the next experiment. The proposed biosensor is able to detect 103 cells. The flow-injection assay of the bacterial cells takes about 30 min.