SURFACE PLASMON RESONANCE AND QUARTZ CRYSTAL MLCROBALANCE IMMUNOSENSORS FOR DETECTION OF ESCHERICHIA COLI O157:H7

摘要

Surface plasmon resonance (SPR) and quartz crystal microbalance (QCM) techniques have been studied in label-free immunosensors for direct detection of bacteria. However, there is a lack of comparative investigations on SPR and QCM immunosensors. In this study, SPR and QCM immunosensors were compared for their applications in bacterial detection using Escherichia coli O157:H7 as a model pathogen. In both immunosensors, affinity-purified polyclonal antibodies were used as capture antibodies and Protein A method was used for antibody immobilization. The stepwise assembly of the immunosensors was characterized by SPR, QCM, and cyclic voltammetry. Both SPR and QCM could detect E. coli O157:H7 in 1 h with detection ranges of lO{sup}5 to 10{sup}8 and 10{sup}6 to 10{sup}8 CFU/mL, respectively. QCM was more sensitive than SPR in terms of both detection limit and signal-to-noise ratio. For both immunosensors, no significant interference was found from brain heart infusion (BHI) broth or Salmonella Typhimurium. The binding efficiency of the QCM immunosensor at 10{sup}5 to 10{sup}8 CFU/mL was found to be 95.9% to 2.9%, decreasing with increasing cell concentration.