Two-dimensional transition metal dichalcogenides (2D TMDs) possess a tunable excitonic light emission that is sensitive to external conditions such as electric field, strain, and chemical doping. In this work, we reveal the interactions between DNA nucleobases, i.e., adenine (A), guanine (G), cytosine (C), and thymine (T) and monolayer WS₂ by investigating the changes in the photoluminescence (PL) emissions of the monolayer WS₂ after coating with nucleobase solutions. We found that adenine and guanine exert a clear effect on the PL profile of the monolayer WS₂ and cause different PL evolution trends. In contrast, cytosine and thymine have little effect on the PL behavior. To obtain information on the interactions between the DNA bases and WS₂, a series of measurements were conducted on adenine-coated WS₂ monolayers, as a demonstration. The p-type doping of the WS₂ monolayers on the introduction of adenine is clearly shown by both the evolution of the PL spectra and the electrical transport response. Our findings open the door for the development of label-free optical sensing approaches in which the detection signals arise from the tunable excitonic emission of the TMD itself rather than the fluorescence signals of label molecules. This dopant-selective optical response to the DNA nucleobases fills the gaps in previously reported optical biosensing methods and indicates a potential new strategy for DNA sequencing.

中文翻译：

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单层WS 2的可调谐激子发射，用于DNA核碱基的光学检测。

二维过渡金属二硫化碳（2D TMD）具有可调谐的激子发光，对外部条件（例如电场，应变和化学掺杂）敏感。在这项工作中，我们通过研究DNA的光致发光（PL）发射的变化，揭示了DNA核碱基之间的相互作用，即腺嘌呤（A），鸟嘌呤（G），胞嘧啶（C）和胸腺嘧啶（T）和单层WS ₂。用核碱基溶液包被后的单层WS ₂。我们发现，腺嘌呤和鸟嘌呤对单层WS ₂的PL谱有明显影响，并导致不同的PL演化趋势。相反，胞嘧啶和胸腺嘧啶对PL的行为影响很小。获取有关DNA碱基与WS ₂之间相互作用的信息演示了在腺嘌呤涂层的WS ₂单层上进行的一系列测量。PL光谱的演化和电传输响应都清楚地表明了在引入腺嘌呤时WS ₂单层的p型掺杂。我们的发现为无标记光学传感方法的发展打开了大门，在无标记光学传感方法中，检测信号来自TMD本身的可调谐激子发射，而不是标记分子的荧光信号。对DNA核碱基的这种掺杂剂选择性光学反应填补了先前报道的光学生物传感方法中的空白，并表明了DNA测序的潜在新策略。