In this study, we reported a ratiometric electrochemiluminescence (ECL) biosensor based on localized surface plasmon resonance (LSPR)-enhanced Ag@Au nanostructures combined with palladium nanoclusters (Pd NCs) catalyzing the luminol-gold nanoparticles (L-Au NPs). Firstly, L-Au NPs were synthesized, hydrogen peroxide (H₂O₂) was used as a co-reactant, and Ag@Au nanostructures acted as an LSPR source to enhance the initial signal at the anode. Next, with the help of strand displacement amplification (SDA), the trace target miRNA let-7a was able to be converted to a number of output DNA. And then the Visual DNA Strand Displacement (DSD) was used to evaluate the conversion efficiency of miRNA let-7a into output DNA, thereby verifying that the SDA achieved signal amplification in the construction of biosensor. It was thereafter experimentally verified that the first decrease in anodic signal was achieved by strand amplification based on magnetic beads and polymerase excitation. In contrast, Pd NCs were synthesized using double-stranded DNA (dsDNA) as a template and excited with a cathodic signal, while a second decrease of the anodic signal was also achieved. The developed ratiometric ECL biosensor demonstrated a sensitive detection of miRNA let-7a with a linear range from 0.1 pM to 10 aM and a detection limit of 5.45 aM (S/N = 3). In conclusion, the study presented a new idea for the construction of ratiometric ECL sensors based on a single luminophore, providing technical support for the early diagnosis of cancer.

中文翻译：

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一种基于 LSPR 的“开-关”比率电化学发光生物传感器，由 Ag@Au 纳米结构结合 Pd NC 催化单个发光团用于 MiRNA let-7a 检测


在这项研究中，我们报道了一种基于局部表面等离子体共振 （LSPR） 增强Ag@Au纳米结构的比率电化学发光 （ECL） 生物传感器，结合钯纳米团簇 （Pd NCs） 催化鲁米诺金纳米颗粒 （L-Au NPs）。首先，合成 L-Au NPs，使用过氧化氢 （H₂O₂） 作为共反应物，Ag@Au纳米结构作为 LSPR 源以增强阳极的初始信号。接下来，在链置换扩增 （SDA） 的帮助下，痕量靶标 miRNA let-7a 能够转化为许多输出 DNA。然后，使用 Visual DNA Strand Displacement （DSD） 评估 miRNA let-7a 向输出 DNA 的转化效率，从而验证 SDA 在构建生物传感器时实现了信号放大。此后实验验证，阳极信号的首次降低是通过基于磁珠和聚合酶激发的链扩增实现的。相比之下，Pd NCs 是使用双链 DNA （dsDNA） 作为模板合成的，并用阴极信号激发，同时也实现了阳极信号的第二次降低。开发的比率式 ECL 生物传感器对 miRNA let-7a 的检测灵敏度高，线性范围为 0.1 pM 至 10 aM，检测限为 5.45 aM （S/N = 3）。综上所述，该研究为构建基于单个发光团的比率式 ECL 传感器提出了新思路，为癌症的早期诊断提供了技术支持。