Binding-induced DNA assembly and its application to yoctomole detection of proteins.

We describe the binding-induced DNA assembly principle and strategy that enable ultrasensitive detection of molecular targets and potential construction of unique nanostructures/nanoreactors. Two DNA motifs that are conjugated to specific affinity ligands assemble preferentially only when a specific target triggers a binding event. The binding-induced assembly of the DNA motifs results in the formation of a highly stable closed-loop structure, raising the melting temperature (T(m)) of the hybrid by >30 °C and enabling effective differentiation of the target-specific assembly from the background. The ability to detect as few as a hundred molecules (yoctomole) of streptavidin, platelet derived growth factor, and prostate specific antigen represents an improvement of detection limits by 10(3)-10(5)-fold over traditional immunoassays. The assay is performed in a single tube, eliminating separation, immobilization, and washing steps of conventional assays. By incorporating unique signaling and structural features into the DNA motifs, we envision diverse applications in biosensing and nanotechnology.