Jungle on the Electrode: A Target-Induced Enzyme-Free and Label-Free Biosensor.

With the development of clinical medicine-related technologies, the detection of cancer biomarkers has become an essential method for cancer diagnosis. DNA self-assembly is a valuable approach to monitor low-abundance miRNA. Herein, we report a novel DNA jungle biosensor for target-induced enzyme-free and label-free ultrasensitive detection of miRNA-21 in biological samples. The method consists of two parts. The target catalyzes the assembly of the hairpin to form the backbone of the DNA jungle, and the auxiliary probes hybridize to form branches freely and undirectedly. The DNA jungle can be self-assembled seeded from a single target initiator, affording the potential for screening a single target molecule. Vitro assays show that the DNA jungle offers very high amplification efficiency and specificity, with a direct detection limit of 1 aM. This DNA jungle strategy can provide a useful platform for low-abundance biomarker detection for cell biology and diagnostics.