title: Probing biomolecular interaction forces using an anharmonic acoustic technique for selective detection of bacterial spores.
abstract: Receptor-based detection of pathogens often suffers from non-specific interactions, and as most detection techniques cannot distinguish between affinities of interactions, false positive responses remain a plaguing reality. Here, we report an anharmonic acoustic based method of detection that addresses the inherent weakness of current ligand dependant assays. Spores of Bacillus subtilis (Bacillus anthracis simulant) were immobilized on a thickness-shear mode AT-cut quartz crystal functionalized with anti-spore antibody and the sensor was driven by a pure sinusoidal oscillation at increasing amplitude. Biomolecular interaction forces between the coupled spores and the accelerating surface caused a nonlinear modulation of the acoustic response of the crystal. In particular, the deviation in the third harmonic of the transduced electrical response versus oscillation amplitude of the sensor (signal) was found to be significant. Signals from the specifically-bound spores were clearly distinguishable in shape from those of the physisorbed streptavidin-coated polystyrene microbeads. The analytical model presented here enables estimation of the biomolecular interaction forces from the measured response. Thus, probing biomolecular interaction forces using the described technique can quantitatively detect pathogens and distinguish specific from non-specific interactions, with potential applicability to rapid point-of-care detection. This also serves as a potential tool for rapid force-spectroscopy, affinity-based biomolecular screening and mapping of molecular interaction networks.
authors: University of Cambridge Nanoscience Centre, 11J. J. Thomson Avenue, Cambridge, Cambridgeshire, CB3 0FF, UK.
authors: Sourav K
authors: SK
authors: Ghosh
authors: Victor P
authors: VP
authors: Ostanin
authors: Christian L
authors: CL
authors: Johnson
authors: Christopher R
authors: CR
authors: Lowe
authors: Ashwin A
authors: AA
authors: Seshia
mesh_terms: D000162:Acoustics; D000907:Antibodies, Bacterial; D055910:Antibodies, Immobilized; D001412:Bacillus subtilis / Q000276:immunology / Q000302:isolation & purification; D001431:Bacteriological Techniques / Q000379:methods / Q000706:statistics & numerical data; D015374:Biosensing Techniques / Q000379:methods / Q000706:statistics & numerical data; D018625:Microscopy, Atomic Force; D008863:Microspheres; D019095:Point-of-Care Systems; D011137:Polystyrenes; D058525:Quartz Crystal Microbalance Techniques / Q000379:methods* / Q000706:statistics & numerical data; D013171:Spores, Bacterial / Q000276:immunology / Q000302:isolation & purification*; D019809:Streptavidin
chemical_list: D000907:Antibodies, Bacterial; D055910:Antibodies, Immobilized; D011137:Polystyrenes; D019809:Streptavidin