Bifunctional bioplatform based on NiCo Prussian blue analogue: Label-free impedimetric aptasensor for the early detection of carcino-embryonic antigen and living cancer cells

A novel bifunctional electrochemical aptasensor based on bimetallic NiCo Prussian blue analogue (NiCoPBA) nanocubes has been constructed for detecting carcino-embryonic antigen (CEA) and corresponding living cancer cells. The NiCoPBA exhibits a regular cubic shape of 100 nm size, with fluorescence and excellent biocompatibility. In view of the intrinsic cavities, metallic coordination centers, rich C N groups, and π-π* interactions of NiCoPBA, the CEA-targeted aptamer strands can be strongly anchored on the surface of nanocubes. Given that the CEA cancer marker is overexpressed on the H460 cell surface of carcinomas, the developed NiCoPBA-based aptasensor not only can be employed to determine CEA in human serum via the formation of stable G-quadruplex between aptamer strands and CEA, but also can be utilized to directly detect cancer cells due to the strong binding force between CEA aptamer and cancer cell. The fabricated sensor shows superior sensing performance toward CEA compared with other reported CEA aptasensors, providing an extremely low limit of detection (LOD) of 0.74 fg mL−1 (1.62 fM) (S/N = 3) in a wide linear range of 1.0 fg mL−1 to 5.0 ng mL−1, as well as an LOD of 47 cells mL–1 for H460 cells. Thereby, the proposed aptasensor may be further used as a promising platform for detecting other cancer markers when anchoring different kinds of aptamers, with potential bifunctional applications in early diagnosis of tumor markers and cancer cells.