Visualization of Single Cell Contour by Umbrella-Shaped Micelle on the Surface of Tumor Cell Induced Specific Recogonized Fluorescence Enhancement and Digital Signal Amplification

The specific membrane protein EpCAM of circulating tumor cell (CTC) was used as the recognition receptor, and the carboxyfluorescein (FAM)-labeled EpCAM aptamer (Apt-FAM) was used as the recognition ligand. After Apt-FAM specifically recognized EpCAM, the fluorophore of FAM was distributed abundantly on the surface of cell. The hydrophobicity of the fluorophore of FAM induced the accumulation of the hydrophobic end of the non-ionic surfactant Tween-80 around the fluorophore to form an umbrella-shaped nanomicelle centered on FAM, which enhanced the specific recognized fluorescence on the surface of cell and improved the signal-to-noise ratio of the fluorescence signal. Using digital signal amplification technology, the membrane fluorescence signal of the imaging cells was amplified, and the contours of the imaging cells were completely and clearly displayed, which realized the visualization of the contours of single cells by specific recognition, and improved the accuracy of count and scale estimation of capturing CTC.