As a kind of excellent biomaterials, deoxyribonucleic acids (DNAs) have been employed to build a variety of biosensors via the interactions between DNAs and biomolecules or chemical compounds. The DNA-based electrochemical biosensors with the advantages of easy operation, rapid response and low cost have been widely used in biochemical analysis with high sensitivity and selectivity. However, most of the DNA-based electrochemical biosensors require the labeling of electroactive molecules or nanomaterials on DNAs as signal read-out elements, which thus inevitably suffer from complicated operation and expensive cost. Label-free strategies are alternatives for DNA-based electrochemical biosensors without additional assay reagents and tedious procedures. Because of the merits of simplicity and low cost, DNA-based label-free electrochemical biosensors have attracted tremendous attention from researchers as a promising analytical technology. In this review, the principles and applications of DNA-based label-free electrochemical biosensing systems including heterogeneous and homogeneous modes with various amplification strategies have been introduced and summarized systematically. Furthermore, the present challenges and further perspectives of the DNA-based label-free electrochemical biosensors are highlighted.

作为一种出色的生物材料，脱氧核糖核酸（DNA）已被用来通过DNA与生物分子或化合物之间的相互作用来构建各种生物传感器。基于DNA的电化学生物传感器以其操作简便，反应迅速，成本低等优点，已被广泛用于生物化学分析中，具有较高的灵敏度和选择性。但是，大多数基于DNA的电化学生物传感器都需要在DNA上标记电活性分子或纳米材料作为信号读出元件，因此不可避免地会遭受复杂的操作和昂贵的成本。无标记策略是基于DNA的电化学生物传感器的替代方案，无需其他测定试剂和繁琐的程序。由于简单和低成本的优点，基于DNA的无标记电化学生物传感器作为一种有前途的分析技术已引起研究人员的极大关注。在这篇综述中，系统地介绍了基于DNA的无标记电化学生物传感系统的原理和应用，包括具有多种扩增策略的异质模式和均质模式。此外，突出了基于DNA的无标记电化学生物传感器的当前挑战和进一步的前景。