The simultaneous imaging of the dynamic expression variations of regulatory RNAs in cells, which remains a major challenge, has important applications in precise disease diagnosis, treatment and prognosis. Here, we describe the establishment of a biodegradable ZnO nanoparticle (NP)-assisted asymmetric amplification approach for the simultaneous imaging of microRNA-21 (miRNA-21) and programmed cell death 4 (PDCD4) mRNA at distinct expression levels in live cells. The DNA signal probe complexes are immobilized on the ZnO NPs and readily delivered into the target cancer cells via the endocytosis pathway. The acidic microenvironment in cancer cells leads to the dissolution of the ZnO NPs to release Zn²⁺ ions and the intracellular miRNA-21 activates the Zn²⁺-dependent DNAzyme to cleave the substrate signal probes with the assistance of the Zn²⁺ cofactor to show green fluorescence for imaging miRNA-21. Meanwhile, the PDCD4 mRNA can displace the other quenched signal probes to generate red fluorescence. Importantly, the PDCD4 mRNA sequences can be recycled and reused by using the DNAzyme-cleaved sequences as the fuel strands through two strand displacement reactions to yield amplified red fluorescence for detecting low levels of PDCD4 mRNA. Moreover, our approach can be used to evaluate the varied expression levels of miRNA-21 and PDCD4 mRNA responsive to different drugs in cells, reflecting its usefulness for precise cancer diagnosis and prognosis upon anticancer drug treatment.

中文翻译：

---

可生物降解的纳米颗粒辅助和多重成像活细胞中不对称 RNA 表达，用于精确的癌症诊断和预后

细胞中调节性 RNA 的动态表达变化的同时成像仍然是一项重大挑战，在精确的疾病诊断、治疗和预后中具有重要的应用。在这里，我们描述了一种可生物降解的 ZnO 纳米颗粒 (NP) 辅助不对称扩增方法的建立，用于在活细胞中以不同的表达水平同时成像 microRNA-21 (miRNA-21) 和程序性细胞死亡 4 (PDCD4) mRNA。DNA 信号探针复合物固定在 ZnO NPs 上，并通过内吞途径容易地递送到靶癌细胞中。癌细胞中的酸性微环境导致 ZnO NPs 溶解释放 Zn ²⁺离子，细胞内 miRNA-21 激活 Zn ^{2+-依赖性脱氧核糖核酸酶，在 Zn 2+}辅因子的帮助下切割底物信号探针，显示绿色荧光，用于 miRNA-21 成像。同时，PDCD4 mRNA可以取代其他猝灭信号探针产生红色荧光。重要的是，PDCD4 mRNA 序列可以通过使用 DNAzyme 切割的序列作为燃料链通过两条链置换反应进行回收和重复使用，从而产生放大的红色荧光，用于检测低水平的 PDCD4 mRNA。此外，我们的方法可用于评估细胞中对不同药物反应的 miRNA-21 和 PDCD4 mRNA 的不同表达水平，反映其对精确癌症诊断和抗癌药物治疗预后的有用性。