Terahertz spectral nondestructive detection of amino acid molecules in aqueous solution

Abstract

Only in liquid environment can most biomolecules maintain their biological activity, the realization of terahertz (THz) spectrum detection of water-bearing biomolecules has an important application value for the research of the function and structure of active biomolecules and non-invasive biomedical detection. In this paper, by using the THz radiation source generated by LiNbO3 light rectification, and combing with the local electric field enhancement effect of the flared gradient parallel flat waveguide, we have built a THz time domain spectral measurement system that can detect the trace amounts of living cells and aqueous biomolecules, which can implement THz spectral detection of 4-aminobenzoic acid and glutamic acid in solution. The results show that 4-aminobenzoic acid and glutamic acid in aqueous solution have obvious and unique characteristic absorption peaks in the frequency band of 0.1–2.0 THz when the effect of water on THz wave absorption is removed. The acquisition of characteristic absorption spectrum of amino acid aqueous solution in THz frequency band lays a foundation for the detection of active biological macromolecules or tissues.