The sensitive and accurate detection of rare
tumor cells provides precise diagnosis and dynamic assessment information in various
tumor spectrums. However, rare
tumor cells assay is still a challenge due to the exceedingly rare presence in the blood. In this research, we develop a fluorescent approach for the identification of rare
tumor cells based on a combination of
immunosorbent capture and a three-step signal amplification strategy. First, rare
tumor cells are captured by immunoadsorption on 96-well plates. Second, self-synthesized tetrahedral framework
nucleic acids (tFNAs) spontaneously anchor into the
lipid bilayer of rare
tumor cells, resulting in a "one to more" amplification effect. Then, the
double-stranded DNA (dsDNA) binds to the vertices of the tFNAs and generates a large amount of target
RNA by T7 polymerase, which is the secondary signal amplification. Finally, the target
RNA activates the collateral cleavage ability of CRISPR/Cas13a, and the reporter
RNA is cleaved for third signal amplification. The detection limit of the proposed method is down to 1 cell mL-1. Furthermore, the tFNAs-Cas13a system is also shown to be capable of detecting rare
tumor cells in spiked-in samples and clinical blood samples. This platform enables speedy detection of rare
tumor cells with high sensitivity and good specificity, and shows great potential for
tumor diagnosis.