Biological Sensing via THz Circular Dichroism

Biological sensing via terahertz circular dichroism (TCD) may provide a reliable method for the detection of life in unknown materials and the characterization of the relevant global and sub-global dynamics of biopolymers. Experimental and theoretical evidence suggest that the major classes of biopolymers absorb electromagnetic radiation strongly at THz frequencies, potentially providing each unique biopolymer with an unambiguous spectral identification. The spectral “finger-print” of biopolymers is typically obscured due to the strong THz absorption features of several common abiological materials such as water. However, all major chemical species involved in biological activity are chiral and typically exhibit a ubiquitous single “handedness,” where as chiral abiological materials typically exist in equal amounts of each handedness (All one thread of screw versus equal amounts of left and right threaded screw). Abiological materials produce no net CD signal (differential absorption of circular polarizations by chiral chromophores¾ different threads of the same screw); therefore spectral analysis through the means of TCD should reveal the unique signatures of biological materials. The goal of our research is to develop a TCD spectrometer and to assess the utility of TCD spectroscopy as a viable means of life detection as well as a classification scheme for biopolymers.