Background

Precise control of the biorecognition process in DNA biosensors, especially for those with signal amplification, remains a challenge. It is of great significance to introduce external stimuli into the DNA system for a controllable trigger of nucleic acid cascade amplification and further for excellent biosensors.

Results

In this study, a photo-initiated hybridization chain reaction (HCR) was designed for controllable and sensitive electrochemical biosensor via the incorporation of azobenzene moiety into the assembly unit. Under the coexistence of UV light and target DNA, a number of HCR products with biotin tags were generated and fixed on the electrode surface. Subsequently, the bound streptavidin-labeled horseradish peroxidase (SA-HRP) effectively catalyzed H₂O₂-mediated oxidation of tetramethylbenzidine (TMB), producing significant electrochemical current signals. A tunable sensing performance with different dynamic response ranges and sensitivity was achieved by adjusting the number of the inserted azobenzene moieties and the control of UV light. A limit of detection as low as 2.5 fM (S/N=3) could be obtained in the case of one azobenzene and under UV exposure. Moreover, the photo-controlled DNA biosensor exhibited good discrimination ability even against single-base mismatch and was able to be applied in serum samples.

Significance

The proposed electrochemical DNA biosensor based on dual-triggered HCR amplification may represent a promising path to achieve sensitive and accurate bioanalysis. Also, the tunable dynamic range of the developed biosensor will provide the possibility of clinical applications.

中文翻译：

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用于扩增电化学生物传感器的光控级联 DNA 杂交，具有可调谐传感性能

 背景

精确控制 DNA 生物传感器中的生物识别过程仍然是一项挑战，尤其是对于具有信号放大功能的传感器。将外部刺激引入 DNA 系统以可控触发核酸级联扩增，进而获得优良的生物传感器具有重要意义。

 结果

在本研究中，通过将偶氮苯部分掺入组装单元，设计了一种光引发杂交链式反应 （HCR），用于可控和灵敏的电化学生物传感器。在紫外光和靶 DNA 共存的情况下，生成了许多带有生物素标签的 HCR 产物并固定在电极表面。随后，结合的链霉亲和素标记的辣根过氧化物酶 （SA-HRP） 有效催化 H₂O₂ 介导的四甲基联苯胺 （TMB） 氧化，产生显著的电化学电流信号。通过调整插入的偶氮苯部分的数量和紫外线的控制，实现了具有不同动态响应范围和灵敏度的可调传感性能。在一种偶氮苯和紫外线照射下，可获得低至 2.5 fM （S/N=3） 的检测限。此外，光控 DNA 生物传感器对单碱基错配也表现出良好的鉴别能力，能够应用于血清样品。

 意义

所提出的基于双触发 HCR 扩增的电化学 DNA 生物传感器可能代表了实现灵敏和准确生物分析的一条有前途的途径。此外，开发的生物传感器的可调动态范围将为临床应用提供可能性。