Terahertz Spectroscopic Signatures of Microcystin Aptamer Solution Probed with a Microfluidic Chip

• Published in: Sensors (Basel, Switzerland) Vol. 19; no. 3; p. 534
• Main Authors: Zhang, Mingkun, Yang, Zhongbo, Tang, Mingjie, Wang, Deqiang, Wang, Huabin, Yan, Shihan, Wei, Dongshan, Cui, Hong-Liang
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI 28-01-2019; MDPI AG
• Subjects: absorption signature; microcystin; microfluidic chip; molecular dynamics; terahertz; microfluidic chip; absorption signature; molecular dynamics; terahertz; microcystin
• ISSN: 1424-8220; 1424-8220
• DOI: 10.3390/s19030534

Terahertz signature detection of biological samples in aqueous solution remains a great challenge due to the strong terahertz absorption of water. Here we propose a new preparation process for fabricating a microfluidic chip and use it as an effective sensor to probe the terahertz absorption signatures of microcystin aptamer (a linear single-stranded DNA with 60 nucleotides) dissolved in TE buffer with different concentrations. The microfluidic chip made of silicon includes thousands of 2.4 μm × 2.4 μm square-cross-section channels. One repeatable terahertz absorption signature is detected and recognized around 830 GHz, fitted to a Lorentz oscillator. This signature is theorized to originate from the bending of hydrogen bonds formed between adjacent hydrated DNA bases surrounded by water molecules. Furthermore, the low-lying vibrational modes are also investigated by molecular dynamics simulations which suggest that strong resonant oscillations are highly probable in the 815⁻830 GHz frequency band.