3D dynamic DNA walker traveling on DNA micelles coupled CRISPR-Cas12a nucleases to recover electrochemiluminescence signal for microcystin-LR detection

Abstract

3D dynamic DNA walker traveling on DNA micelles coupled CRISPR-Cas12a nucleases sensor was proposed to recover electrochemiluminescence (ECL) signal for microcystin-LR (MC-LR) detection. The 3D DNA walker was anchored in DNA micelles, self-assembled from amphiphilic DNA by the hydrophobicity of cholesterol and the electrostatic repulsion of the phosphate backbone. By the MC-LR stimulus, the released swing arm DNA hybridized with the track DNA while cleaving the hairpin structure to obtain the track DNA fragments. The track DNA fragments hybridized with the H1 hairpin structure to form a double-helix structure with PAM sequences, which could activate the Cas12a nucleases for trans-cleavage of the Fc probe-labeled ssDNA to induce ECL signal recovery. The DNA micelles maintained the morphological stability and free diffusion ability of the 3D DNA walker in the biofluidic state and overcome the collisional hindrance for facilitating efficient intraparticle and interparticle walking motions. Meanwhile, the coupled trans-cleavage activity of Cas12a nucleases improved the signal-amplification performance and achieved higher sensitivity with a detection limit of 0.015 pM. Acceptable results confirmed the ability of DNA micelles to stabilize 3D DNA walkers and the validated cleavage activity of Cas12a nucleases.