Xerogel Protein Substrates for Far Infrared Studies

A number of researchers are attempting to develop a biosensor based on terahertz sensing. Key to the realization of any biosensor system is the access of the target molecules to the sensor. In the case of using terahertz spectroscopy, there are limitations due to high attenuation by water and sensitivity levels. In order to have a significant response at THz frequencies generally requires a minimum pathlength of 100 microns. Solid thin films of this thickness will have limited interaction with target molecules. We propose to use xerogels as biomolecular probe substrates. We have characterized the THz transmission of xerogel substrates as a function of hydration and protein content. These measurements demonstrate that xerogels are excellent candidates for biomolecular probe substrates to realize THz biosensors.