The expression levels of microRNA (miRNA) vary significantly in correlation with the occurrence and progression of cancer, making them valuable biomarkers for cancer diagnosis. However, their quantitative detection faces challenges due to the high sequence homology, low abundance and small size. In this work, we established a strand displacement amplification (SDA) approach based on miRNA-triggered structural “Lock” nucleic acid (“Lock” DNA), coupled with the CRISPR/Cas12a system, for detecting miRNA-21 in breast cancer cells. The “Lock” DNA freed the CRISPR-derived RNA (crRNA) from the dependence on the target sequence and greatly facilitated the extended detection of different miRNAs. Moreover, the CRISPR/Cas12a system provided excellent amplification ability and specificity. The designed biosensor achieved high sensitivity detection of miRNA-21 with a limit of detection (LOD) of 28.8 aM. In particular, the biosensor could distinguish breast cancer cells from other cancer cells through intracellular imaging. With its straightforward sequence design and ease of use, the Lock-Cas12a biosensor offers significant advantages for cell imaging and early clinical diagnosis.

中文翻译：

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用于乳腺癌细胞中 miRNA-21 检测和成像的高灵敏度 Lock-Cas12a 生物传感器

microRNA (miRNA) 的表达水平与癌症的发生和进展相关，显着变化，使其成为癌症诊断的有价值的生物标志物。然而，由于其序列同源性高、丰度低、尺寸小，其定量检测面临挑战。在这项工作中，我们建立了一种基于miRNA触发的结构“锁”核酸（“锁”DNA）的链置换扩增（SDA）方法，结合CRISPR/Cas12a系统，用于检测乳腺癌细胞中的miRNA-21。 “锁”DNA使CRISPR衍生的RNA（crRNA）摆脱了对靶序列的依赖，极大地方便了不同miRNA的扩展检测。此外，CRISPR/Cas12a系统提供了优异的扩增能力和特异性。设计的生物传感器实现了 miRNA-21 的高灵敏度检测，检测限 (LOD) 为 28.8 aM。特别是，生物传感器可以通过细胞内成像区分乳腺癌细胞和其他癌细胞。 Lock-Cas12a 生物传感器凭借其简单的序列设计和易用性，为细胞成像和早期临床诊断提供了显着的优势。