Label-Free Ultrathin Pt Film Biosensor Using Phonon Vibrations Excited by Ultrafast Light Pulses

An ultrathin film oscillator biosensor is presented for highly sensitive monitoring of binding reactions among biomolecules in solutions. The phonon vibration along the thickness direction of an 18-nm Pt film is measured by ultrafast light pulses, whose fundamental resonance frequency is 120 GHz. The vibrational amplitude is monitored during binding reaction between human immunoglobulin G (hIgG) and anti-hIgG antibody, which exponentially decreases as the reaction progresses. A 6 pM hIgG solution can be detected. This biosensor also shows the ability to determine the affinity between proteins through the concentration dependence of the reaction rate. ©2010