A self-catalytic UCNP-based nanomachine activated by duplex DNA for highly sensitive detection of CTCs

Detection of circulating tumor cells (CTCs) has proven to be a crucial approach for early diagnosis, prognosis, and monitoring of cancer treatment. However, due to the low abundance of CTCs in blood, achieving accurate detection in the presence of a large number of blood cells remains challenging. In this study, we present a novel self-catalytic nanomachine for quantitative detection of CTCs, which includes a dual aptamer-triggered Catalytic Hairpin Assembly (CHA) reaction and subsequent UCNP-DNA-based biosensing. The dual-aptamer recognition, the two-step CHA reaction and the UCNP ratiometric sensing luminescence provide the assay with high specificity and sensitivity. Using MDA-MB-231 cells as model targets, the proposed detection system affords a wide linear detection range and a detection limit as low as 3 cells. Our system offers sensitive detection of CTCs without the need for enzymatic involvement, indicating its substantial potential for early cancer diagnosis and treatment based on CTCs.