High-intensity fluorescence imaging and sensitive electrochemical detection of cancer cells by using an extracellular supramolecular reticular DNA-quantum dot sheath.

Acting as a cage-type cellular probe, an extracellular supramolecular reticular DNA-quantum dot (QD) sheath has been developed for high-intensity fluorescence microscopy imaging and the sensitive electrochemical detection of Ramos cells. The extracellular supramolecular reticular DNA-QD sheath is constructed from layer-by-layer self-assembly of DNA-CdTe QD probes and DNA nanowire frameworks functionalized with a Ramos cell-binding aptamer. The DNA-QD sheath forms specifically and quickly on the surface of Ramos cells at physiological temperature, and the assembly of large numbers of DNA-CdTe QD probes on the surface of Ramos cells produces exceedingly high fluorescence intensity. Using the extracellular supramolecular reticular DNA-QD sheath as the cellular probe, Ramos cells can be clearly observed and easily distinguished from a mixture of multiple cancer cells by fluorescence microscopy imaging. Using the new cage-type cellular probe, a sensitive sandwich-type electrochemical strategy has also been developed to achieve accurate quantitative analysis of Ramos cells. Under the optimized conditions, Ramos cells can be detected quantitatively in a range from 10 to 1000 cells with a detection limit of 10 cells. This strategy presents a promising platform for highly sensitive and convenient evaluation of cancer cell levels.