Liping Wang, Xu Wu, Yan Peng, Qingrou Yang, Xiaohong Chen, Wanwan Wu, Yiming Zhu, and Songlin Zhuang
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| (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. |
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 ( = 0.99809) is much larger than that of the Raman spectrum ( = 0.80022, = 0.8028). These results are greatly useful for the accurate evaluation of pathological stage.
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