Bond rupture of biomolecular interactions by resonant quartz crystal

Significant progress has been achieved in understanding affinity-based diagnostics, which use the highly specific "lock and key" recognition and binding between biomolecules, for example, an antibody and its antigen. These are the most specific of analytical tests. One of the most challenging issues is to distinguish between true binding and ever-present nonspecific binding in which more loosely bound proteinaceous material gives false results in conventional affinity methods. We have used bond-rupture scanning to eliminate nonspecific binding by introducing energy mechanically through displacement of a resonant quartz crystal. The removal of the analyte was recorded with a simple all-electronic detection system quickly providing confirmation of the presence of the target molecule. The system can measure the resonant frequency difference and detect noise signals, respectively, due to mass changes and bond breaks between biotinylated self-assembled monolayer (SAM) and streptavidin-coated polystyrene microspheres (SCPM). Both static and dynamic scanning modes can reveal previously unrecognized desorption of streptavidin-coated polystyrene microspheres. An established framework of bond-rupture scanning is a promising diagnostic tool for investigating the specific and nonspecific interactions by measuring the characteristic level of mechanical energy required to break the bond.