THz signatures of DNA in nanochannels under electrophoretic control

Abstract

During the past several years we have utilized our nanofluidic-chip technology and high-resolution frequency-domain THz spectroscopy to detect absorption signatures in biomolecules and bioparticles of various types, especially the nucleic acids. Some of the signatures have been surprisingly narrow (<; 20 GHz FWHM), leading to the hypothesis that the nanofluidic chips can enhance certain vibrational resonances because of their concentrating and linearizing effects. In this work, we take the technology one step further by utilizing electrophoretic control of the absorbing biomolecules. A demonstration is provided of the variation in THz transmission through aqueous Lambda DNA at fixed frequency at one of its strongest sub-THz solutions. The THz transmission is found to be highly correlated to the electrophoretic current in the nanochannels, and to decrease with time. This is consistent with an increasing DNA concentration, or increasing oscillator strength, by the electrophoretic effect.