miRNA作为基因表达的转录后调节因子，与人类许多重大疾病尤其是癌症密切相关。因此，其精确检测对于疾病的诊断和治疗非常重要。随着荧光染料和成像技术的进步，焦点已从体外 microRNA (miRNA) 检测转向体内 miRNA 成像。本概念综述总结了信号放大策略，包括DNAzyme催化反应、混合链式反应(HCR)、催化发夹组装(CHA)，以增强低表达miRNA的检测信号；紫外线（UV）光或近红外区（NIR）光的外部刺激，以及三磷酸腺苷（ATP）、谷胱甘肽（GSH）、蛋白酶和细胞膜蛋白等内部刺激，以防止非特异性激活，避免假阳性信号;以及开发用于体内 miRNA 成像的近红外发射荧光探针；以及基于稀土纳米颗粒的第二近红外窗口 (NIR-II) 纳米探针，具有出色的组织穿透力和深度，适用于体内 miRNA 成像。概念回顾还指出了目前体内 miRNA 成像面临的挑战，包括动态监测 miRNA 表达变化和多个 miRNA 的同步体内成像。© 2024 Wiley‐VCH GmbH。

As a post transcriptional regulator of gene expression, miRNA is closely related to many major human diseases, especially cancer. Therefore, its precise detection is very important for disease diagnosis and treatment. With the advancement of fluorescent dye and imaging technology, the focus has shifted from in vitro microRNAs (miRNA) detection to in vivo miRNA imaging. This concept review summarizes signal amplification strategies including DNAzyme catalytic reaction, hybrid chain reaction (HCR), catalytic hairpin assembly (CHA) to enhance detection signal of lowly expressed miRNAs; external stimuli of ultraviolet (UV) light or near-infrared region (NIR) light, and internal stimuli such as adenosine triphosphate (ATP), glutathione (GSH), protease and cell membrane protein to prevent nonspecific activation for the avoidance of false positive signal; and the development of fluorescent probes with emission in NIR for in vivo miRNA imaging; as well as rare earth nanoparticle based the second near-infrared window (NIR-II) nanoprobes with excellent tissue penetration and depth for in vivo miRNA imaging. The concept review also indicated current challenges for in vivo miRNA imaging including the dynamic monitoring of miRNA expression change and simultaneous in vivo imaging of multiple miRNAs.© 2024 Wiley‐VCH GmbH.