Acoustic immunosensor for real-time sensing of neurotransmitter GABA

An immunosensing method is described for the measurement of /spl gamma/-amino-4-butyric acid (GABA), one of two inhibitory neurotransmitters in the central nervous system. Monoclonal antibody for GABA was immobilized on the gold electrodes of quartz crystal. Binding of GABA produced a decrease in the resonant frequency of quartz crystal. In in-vitro experiments, the sensor demonstrated a sensitivity of 600Hz decrease in resonant frequency in response to 49 mM change in GABA concentration. The response time was less than 10 seconds. The binding sites of immobilized antibody were successfully regenerated by repeated washing with ImM HCl solution. A significant increase in the resistance of the electrical model of the quartz crystal indicated an increase in the viscosity due to the binding of GABA to the anti-body. An acoustic immunosensor sensitive and specific to GABA was demonstrated. Real-time sensing of GABA will enable greater insights into several neuropathologies like epilepsy, Parkinson's disease etc. where the role of GABA is critical.