Abnormally high level of methylation in the epigenome is a biomarker for various forms of cancer. It has been reported that a methylated nucleoside, 5-methylcytidine, when dissolved in water and then frozen, has a resonance absorption peak around 1.6 THz, which could allow for the determination of the degree of methylation using terahertz spectroscopy. This study attempts to replicate the experiment and reproduce this observation independently. Samples of ice were measured at 173 K to establish a baseline and frozen solutions of 5-methylcytidine were measured. Normal (physiological) 0.15 M saline, which is known to have a peak at 1.6 THz, was also measured. The use of a Gaussian function to fit a baseline to the broad (0.2 to 2.5 THz) absorption spectra consistently produced a peak residual around 1.6 THz for all three types of samples, with saline having the highest peak followed by ice. The peak for 5-methylcytidine was found to be smaller than that for ice, which contradicts previously published findings and illustrates the strong dependence of the result on the method of baseline fitting.

表观基因组中异常高水平的甲基化是各种形式癌症的生物标志。据报道，甲基化的核苷5-甲基胞苷，当溶于水然后冷冻时，在1.6 THz附近有一个共振吸收峰，这可以使用太赫兹光谱法测定甲基化程度。这项研究试图复制实验并独立地重现这一观察结果。在173 K下测量冰样品以建立基线，并测量5-甲基胞嘧啶的冷冻溶液。还测量了已知的1.6 MHz峰值的0.15 M生理盐水。对于所有三种类型的样品，使用高斯函数使基线适合宽广的光谱（0.2至2.5 THz），始终在1.6 THz附近产生峰残留，盐水的峰值最高，其次是冰。发现5-甲基胞苷的峰小于冰的峰，这与先前发表的发现相矛盾，并且说明了结果对基线拟合方法的强烈依赖性。