MicroRNAs (miRs) as biomarkers for early cancer diagnostic, were detected through a developed ultrasensitive electrochemical biosensor containing gold Nano-islands (Au-NIs) structures. Different concentrations of miR-21 (from zepto -molar to micro range) in both standard solution and blood serum samples were measured to test the sensitivity of biosensor. A high surface-area-to-volume ratio of nanostructures embellished on the FTO electrodes increases the chance of immobilization of the thiol modified capture probe (anti-miR-21 or cap-21). The Au-nanostructures surface modification and its ability to hybridize successfully and stably anti-miR-21 and miR-21 confirmed by electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV) electrochemical techniques. The results showed that the linear detection range of the biosensor was from 1.0 zM to 200 nM with a limit of detection (LOD) of 0.12 zM which revealed a very high sensitivity. The selectivity of the biosensor was also investigated and confirmed by detecting miR-9 and miR-486. Corresponding results revealed that the biosensor discriminated target miR-21 from non-complementary miR-21 and showed high selectivity and specificity. Our results also revealed that this platform is a promising substrate to quantitative analysis of miR-21 in physiological samples and could be used for biomedical research and point-of-care (POC) diagnosis. Straightforward and robust Au-NIs surface fabricated without surfactant and stabilizer additive, with plenty of anchors for ssDNA immobilization, as well as well-established hybridization and immobilization procedures, plus high electron transfer rate ability in comparison to bare FTO electrodes are among attractive and suitable novelty of this study.

MicroRNAs (miRs) 作为早期癌症诊断的生物标志物，通过开发的包含金纳米岛 (Au-NIs) 结构的超灵敏电化学生物传感器进行检测。测量标准溶液和血清样品中不同浓度的miR-21（从zepto-molar到微量级）以测试生物传感器的灵敏度。修饰在 FTO 电极上的纳米结构的高表面积与体积比增加了硫醇修饰捕获探针（anti-miR-21 或 cap-21）的固定化机会。电化学阻抗谱 (EIS) 和循环伏安法 (CV) 电化学技术证实了金纳米结构的表面改性及其成功和稳定地杂交抗 miR-21 和 miR-21 的能力。结果表明,生物传感器的线性检测范围为1. 0 zM 至 200 nM，检测限 (LOD) 为 0.12 zM，显示出非常高的灵敏度。还通过检测 miR-9 和 miR-486 来研究和确认生物传感器的选择性。相应的结果表明，生物传感器区分靶标 miR-21 和非互补 miR-21，并显示出高选择性和特异性。我们的结果还表明，该平台是定量分析生理样品中 miR-21 的有前途的底物，可用于生物医学研究和即时 (POC) 诊断。直接和坚固的 Au-NIs 表面制造，无需表面活性剂和稳定剂添加剂，具有大量用于 ssDNA 固定的锚点，以及完善的杂交和固定程序，