Quantum dots owing to their unique properties have been the subject of extensive investigations in different areas of science and technology in the past two decades. In this study, preparation of the electrochemical sensor for the selective and sensitive determination of guanine (G) and adenine (A), two of the most important components of DNA and RNA, were investigated by modifying a glassy carbon electrode (GCE) with ZnS@CdS quantum dots and graphene oxide (GO). This sensor shows separated and well-defined peaks for A and G, by which one can determine these biological bases individually or simultaneously. The novel electrode showed linear responses towards G and A over the concentration range of 0.01 μM to 50 μM. Detection limit was determined as 1.45 and 1.81 nM according to signal to noise ratio (S/N = 3). Furthermore, the measurements of thermally denatured single-stranded DNA were carried out and the value of (G + C) / (A + T) of DNA was calculated as about 0.77 for various DNA samples. The proposed electrochemical sensor exhibited some advantages in terms of simplicity, rapidity, high sensitivity, good reproducibility and long-term stability. The relative standard deviation of the proposed system, obtained using A and G standards, were 2.7% and 1.5% for intra-day and 4.3% and 4.1% for inter-day precisions, respectively. The results demonstrated that the proposed electrochemical sensor not only provides a novel and sensitive approach to detecting purine bases, but also ascertained that the proposed electrochemical sensor can be profitable to evaluate DNA bases damage.

在过去的二十年中，由于其独特的性质，量子点已成为科学和技术领域中广泛研究的主题。在这项研究中，通过用ZnS修饰玻碳电极（GCE），研究了用于选择性和灵敏测定鸟嘌呤（G）和腺嘌呤（A）（DNA和RNA的两个最重要成分）的电化学传感器的制备。 @CdS量子点和氧化石墨烯（GO）。该传感器显示出A和G的分离峰和明确定义的峰，通过该峰可以分别或同时确定这些生物学碱基。新型电极在0.01μM至50μM的浓度范围内显示出对G和A的线性响应。根据信噪比（S / N = 3）将检测极限确定为1.45和1.81 nM。此外，进行热变性的单链DNA的测量，并且对于各种DNA样品，DNA的（G + C）/（A + T）的值被计算为约0.77。所提出的电化学传感器在简单性，快速性，高灵敏度，良好的再现性和长期稳定性方面表现出一些优点。使用A和G标准获得的拟议系统的相对标准偏差，日内精度分别为2.7％和1.5％，日间精度分别为4.3％和4.1％。结果表明，提出的电化学传感器不仅提供了一种新颖，灵敏的检测嘌呤碱基的方法，而且还确定了提出的电化学传感器对于评估DNA碱基的损伤是有利的。