A Simple and Sensitive Detection of OmpA Protein from Escherichia Coli by Quartz Crystal Microbalance

The ability to produce indigenous diagnostic tests for neonatal meningitis, that are novel, specific yet cost-effective would now provide a huge impact on public health management in developing countries. Escherichia coli (K1) is the major cause of neonatal meningitis through the interaction with human brain microvascular endothelial cells (HBMEC). Outer membrane protein A (OmpA) is a major protein in the E. coli outer membrane. However, there is not any rapid detections for OmpA. We proposes the construction of a molecular recognition layer composed of thiol molecules and further activation with EDC-NHS complexes on the surface of a quartz crystal microbalance (QCM). Immobilization of antibodies onto the crystal will be allowed to detect OmpA antigens for nanomedicine applications. This study originally developed the aforementioned QCM method to rapidly detect OmpA antigen. The method utilizes the piezoelectric immunosensor onto whose thiol activated crystal surface the affinity-purified antibodies would be immobilized, and the main objective of this study is to optimize the surface monolayer conditions to provide efficient binding of anti-OmpA IgG antibody and to exploit sensing surface for the detection of OmpA antigen, as an alternative diagnostic test. Though the frequency shift was lower for OmpA antibody, still it can able to detect lower than 20 ng /ml of OmpA antigen. The detection of OmpA protein by QCM method is comparatively simple and sensitive than other systems.