Tumor cells circulating in blood are markers for the early detection and prognosis of cancer. However, detection of these cells is challenging because of their scarcity. Conventional techniques for the detection of circulating tumor cells (CTCs) require complicated enrichment before detection because a sample of 10 million blood cells only contains about one tumor cell.  

A research team led by Prof. CHEN Xueyuan and Prof. CHEN Zhuo at Fujian Institute of Research on the Structure of Matter (FJIRSM) of the Chinese Academy of Sciences, worked with no enrichment step and directly detected CTCs in blood samples. 

This ultrasensitive method for the direct detection of CTCs in blood samples has been developed based on the amplified, time-resolved fluorescence measurement of luminescent lanthanide ions released from nanoparticles that bind specifically to tumor cells.  

Researchers found that background signals caused by the autofluorescence of cell components only last for a few nanoseconds and fade before the measurement begins, which increases the sensitivity of the measurements, making it possible for the researchers to detect a single tumor cell per microplate well. 

Tests with blood samples from cancer patients registered as few as 10 cells per milliliter of blood. Fourteen out of fifteen cancer patients were correctly identified by this new method. The number of tumor cells in the samples correlated strongly with the stage of cancer in each patient. 

This study demonstrates the great promise of CTC detection in monitoring cancer progression. However, heterogeneous expression of the antigen on CTCs may influence the detection performance of current nanoprobes with single‐antibody labeling. Researchers are expecting to solve the potential deficiency rationally by designing nanoprobes labeled with multiple antibodies.  

The study entitled "Direct Detection of Circulating Tumor Cells in Whole Blood Based on Time-Resolved Luminescent Lanthanide Nanoprobes" was published in Angewandte Chemie International Edition. 

Direct detection of CTCs in whole blood using time-resolved luminescent lanthanide nanoprobes. (Image by Prof. CHEN's Group)