Cascade signal amplification for sensitive detection of cancer cell based on self-assembly of DNA scaffold and rolling circle amplification

Combined with a DNA aptamer recognition element, a cascade signal amplification strategy for sensitive detection of cancer cell has been developed by coupling target triggered self-assembly of polycatenated DNA scaffold and rolling circle amplified synthesis of DNAzymes. The aptamers for Ramos cells and the complementary oligonucleotides are firstly hybridized to form duplex structure. When the target Ramos cells are introduced, the complementary oligonucleotides of the cell-specific aptamers are released and trigger the assembly of circular DNA to form polycatenated DNA scaffold. Upon recognition by a nicking endonuclease (NEase), the circular DNA templates are dissociated to form the DNA scaffold and further initiate the rolling circle amplification reaction (RCA) to form a linear array of DNAzymes which can catalyze the oxidation of luminol by H2O2 to generate chemiluminescence signal upon binding of hemin. Using this cascade signal amplification strategy, Ramos cells can be sensitively and selectively detected. This proposed method offers a great promise for rapid, simple and sensitive analysis of biological samples.