Abstract-Quantitative analysis of homocysteine in liquid by terahertz spectroscopy

Liping Wang, Xu Wu, Yan Peng, Qingrou Yang, Xiaohong Chen, Wanwan Wu, Yiming Zhu, and Songlin Zhuang

(a) Molecular formula of homocysteine, (b) THz spectrum of pure homocysteine powder, (c) variable spectrum of homocysteine aqueous solution as the vacuum drying, (d) time variable amplitudes of absorption peaks corresponding to Fig. 1(c).

https://www.osapublishing.org/boe/abstract.cfm?uri=boe-11-5-2570

Homocysteine (C4H9NO2S) is a variant of the amino acid cysteine, a harmful substance to the human body, which is closely related to cardiovascular disease, senile dementia, fractures, et al. At present, conventional methods for detecting homocysteine in biological samples include high performance liquid chromatography (HPLC), fluorescence polarization immunoassay (FPIA), and enzymatic cycling methods. These methods have the disadvantages of being time-consuming, sample-losing, chemical reagent-using and operation-cumbersome. Here, we present a method for the quantitative detection of homocysteine in liquid based on terahertz spectroscopy. Considering the strong absorption of water for terahertz beam, we also put forward a pretreatment method for drying samples at low temperature. These methods make the detection limit for homocysteine reach 10 µmol/L (human normal concentration). Based on the linear relationship between the homocysteine concentration and the THz spectral intensity, we can successfully achieve quantitative, accurate and real-time detection of homocysteine. As compared to Raman spectroscopy, the correlation coefficient of THz spectrum (R216.24THz${\text{R}}_{16.24\text{THz}}^2$ = 0.99809) is much larger than that of the Raman spectrum (R22558.26cm−1${\text{R}}_{2558.26\text{c}{\text{m}}^{-1}}^2$ = 0.80022, R22937.32cm−1${\text{R}}_{2937.32\text{c}{\text{m}}^{-1}}^2$ = 0.8028). These results are greatly useful for the accurate evaluation of pathological stage.

© 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Abstract-Structural changes of Bombyx mori fibroin from silk gland to fiber as evidenced by Terahertz spectroscopy and other methods

• Xu Wu^a, 
• Xiaodong Wu^a, 
• Min Shao^b, 
• Bin Yang^a, b, , 

• ^a College of Materials and Textile, Zhejiang Sci-Tech University, Hangzhou 310018, China
• ^b Key Laboratory of Advanced Textile Materials and Manufacturing Technology, Ministry of Education, Zhejiang Sci-Tech University, Hangzhou 310018, China

http://www.sciencedirect.com/science/article/pii/S0141813017311303

Here we investigated the structural changes of silk fibroin during Bombyx mori silkworm spinning and reconstitution process. X-ray diffraction, Fourier transform infrared spectroscopy, polarized optical microscopy, and terahertz (THz) spectroscopy were applied to monitor the structural features of silk fibroin from posterior, middle silk glands, to cocoons, and then to reconstituted silk.