Label-free bioaffinity detection using terahertz technology

We report the first use of differential terahertz time-domain spectroscopy for bioaffinity sensing. Binding is observed by measuring the transmission of a thin layer of biotin bound to the sensor protein avidin. We demonstrate the THz wave transmission of a sub-micron-thick film and sensitivity to 0.1 mug cm(-2) of biotin. These results point the way for a host of biosensor applications using T-rays, or pulsed far-infrared (FIR) radiation.