Photoelectrochemical and fluorescent dual-mode sensitive detection of circulating tumor cells based on aptamer DNA-linked CdTe QDs/Bi2MoO6/CdS "double Z-scheme" system.

Herein, a novel dual-mode biosensor integrating photoelectrochemical (PEC) and fluorescence (FL) sensing detection was developed for circulating tumor cells (CTCs) based on aptamer DNA-linked CdTe QDs (Apt-CdTe QDs)/Bi2MoO6/CdS "dual Z-scheme" sensing system. Apt-CdTe QDs were assembled on FTO/CdS/Bi2MoO6/cDNA electrode through hybridization with cDNA, resulting in the formation of a double Z-scheme CdS/Bi2MoO6/CdTe heterostructure that significantly enhanced the separation of photo-generated charge carriers, thereby improving photocatalytic efficiency. Upon the presence of MCF-7 cells, Apt-QDs were captured and subsequently released from the captured electrode, leading to a decrease in photocurrent and an increase in fluorescence intensity, thus enabling effective PEC-FL dual-mode detection. The detection of CTCs exhibited a linear relationship within the concentration range from 50 to 100000 cells mL-1 with limit of detection of 1 cell mL-1 in both PEC and FL modes. This approach effectively corrected systematic errors, improved detection accuracy and sensitivity, and held great potential in the clinical detection of CTCs.