A double 3D DNA walker nanomachine by DNAzyme self-driven positive feedback loop amplification for the detection of miRNA was constructed. This method uses two gold nanoparticles as the reaction core, and because of the spatial confinement effect the local concentration of the reactants increase the collision efficiency was greatly improved. Meanwhile, the introduction of positive feedback loop promotes the conversion efficiency. In presence of miRNA-21, a large amount of DNAzyme was released and hydrolyze the reporter probe, resulting the recovery of fluorescence signal. The linear range for miRNA-21 is 0.5–60 pmol/L, and the detection limit is 0.41 pmol/L (S/N = 3). This nanomachine has been successfully used for accurate detection of miRNA-21 expression levels in cell lysates. At the same time, it can enter cells for intracellular miRNA-21 fluorescence imaging, distinguishing tumor cells from normal cells. This combination of in vitro detection and imaging analysis of living cells can achieve the goal of jointly detecting cancer markers through multiple pathways, providing new ideas for early diagnosis and screening of diseases.

中文翻译：

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基于 DNAzyme 正反馈环的双核 3D DNA 纳米机器，用于活细胞中高灵敏度的 MicroRNA 成像

构建了用于检测miRNA的DNAzyme自驱动正反馈环放大的双3D DNA walker纳米机器。该方法采用两个金纳米粒子作为反应核心，由于空间限域效应，反应物的局部浓度增加，碰撞效率大大提高。同时，正反馈环路的引入提高了转换效率。当miRNA-21存在时，大量DNAzyme被释放并水解报告探针，导致荧光信号恢复。 miRNA-21 的线性范围为 0.5–60 pmol/L，检测限为 0.41 pmol/L (S/N = 3)。该纳米机器已成功用于准确检测细胞裂解物中的 miRNA-21 表达水平。同时，它可以进入细胞进行细胞内miRNA-21荧光成像，区分肿瘤细胞和正常细胞。这种活细胞体外检测与影像分析相结合，可以实现多途径联合检测癌症标志物的目标，为疾病的早期诊断和筛查提供新思路。