Spatially Selective MicroRNA Imaging in Human Colorectal Cancer Tissues Using a Multivariate-Gated Signal Amplification Nanosensor.

MicroRNA (miRNA) is involved in the genesis in viand development of colorectal cancer. The in vivo imaging of miRNA at the tumor sites is essential for understanding its role in colorectal cancer pathology and therapeutic target identification. However, achieving accurate imaging of miRNA at the tumor sites is hindered by the low abundance of miRNAs in tumor cells and nonspecific signal leakage in normal tissues. Here, we report a multivariate-gated catalytic hairpin assembly (CHA) nanosensor for the specific amplified imaging of microRNA-21 (miR-21) in human colorectal cancer tissues to reveal the underlying miR-21-associated molecular mechanism. The endogenous glutathione and exogenous near-infrared multivariate-gated design in combination with CHA probes improves the signal strength of target miR-21 and reduces the background interference. The nanosensor enables specific amplified imaging of miR-21 in vivo, and the signal-to-background ratios are 1.6-fold compared with traditional CHA methods. With the assistance of the designed nanosensor, we achieve the preliminary identification of tumor tissues and normal tissues from human clinical surgical resection samples. The overexpressed miR-21 is found to suppress the core mismatch repair recognition protein human mutS homologue 2 involved in DNA damage recognition and repair to inhibit the therapeutic efficacy of colorectal cancer. The strategy of probe design, which combines multivariate-gated activation methods with a signal amplification system, is applicable for accurate miRNA imaging and disease-relevant molecular mechanism research.