The overall objective is to develop a novel microcantilever-based array immunosensor which is highly-sensitive, highly selective, precise, accurate, rapid, field-deployable, robust, low-cost and allows the simultaneous detection and quantification of small analytes. The proposed sensor will be based on the combination of the force measurement transduction mechanism and the receptor-ligand biological interaction recognition principle to realize the high sensitivity and selectivity. Trinitrotoluene (TNT), atrazine (ATZ), and biotin will be studied as model analytes. Single chain antibody fragment (scFv) against TNT and ATZ with low affinity and high off-rate for the respective analogs will be generated using directed evolution. The selected scFv will be immobilized on the microcantilever tip to which agarose beads functionalized with the analog will be suspended and the adhesive force measured. The introduction of the target analyte that has higher affinity and high on-rate to this system will result in the displacement of the attached bead and hence rupture of the adhesive force. The time required to rupture the linkage will be correlated to the concentration of the analyte. The knowledge gained and the sensors developed through this research will introduce novel biosensor design concepts for the applications in health care, homeland security, food monitoring and quality control, etc. The proposed effort will have impact on teaching and training of the next generation work force in the traditional areas of molecular biology and physics and the emerging multidisciplinary subject of sensors/biosensors, nanobiotechnology and microfabrication.
